How can I tell what cam is in my old 86 4.2?
05-22-2004, 02:26 AM
#31
Guest
Posts: n/a
Re: How can I tell what cam is in my old 86 4.2?
http://www.----------.com/IskyRR1000.jpg
God Bless America, ßill O|||||||O
mailto:--------------------
c wrote:
>
> You can do it and get pretty close Mike. The important numbers are how many
> degrees the LIFTER is above .050 lift. This is the industry standard for
> measuring camshaft duration. Advertised duration measurement methods vary
> between manufacturers, so I would be leery about measuring how many degrees
> the lifter is above zero lift. Some cam companies use a small amount of the
> lift to act as lifter preload, especially for hydraulic cams.
>
> To measure the cam, it is best to have access to the lifter with a dial
> indicator, but you can get close with a hydralic one. You can also do the
> lift measurement at the valve, but then you are reling on the rocker arm
> ratio being correct, and you are also assuming that there is no part
> deflection anywhere.
>
> Anyway, the recommended way to do this is with a cam degree wheel. Basically
> it is the protractor you talked about using, but is calibrated a full 360
> degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> degree wheel, this is what it is:
> http://static.summitracing.com/globa...e/mrg-1570.jpg
>
> The pro engine builders use a very large diameter wheel to get their
> camshafts degreed in as close as possible.
>
> Once you have something like this, you can rig up some kind of a pointer for
> the wheel. I used to use a piece of a metal coat hanger and bend it to
> shape. For your purposes this will be plenty accurate. Now you need a dial
> indicator to measure the lift at the valve or at the lifter. If you do it at
> the valve, you need to know the rocker arm ratio for your engine. I will
> assume for my explanation that it is 1.5. If you are meauring the valve lift
> you will need to turn the engine in its normal rotation and take a reading
> on the degree wheel when the valve reaches .075 lift. You could crudely do
> this with a dial caliper as well by meauring from the top of the valve
> spring retainer to the valve spring seat on the head.
>
> Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> Now turn the engine until the valve is at maximum lift and record that.
> (.450 for my example). Rotate the engine until the valve comes down to .075
> lift again and record that number (25 ABDC for my example). You can now
> determine the intake lobe and where it is reaching peak lift. Take the BTDC
> number, add 180, and add the ABDC number to get 220. This is your duration
> at .050 tappet lift. To determine the lobe center angle, divide the duration
> in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> ratio, so .450/1.5 = .300 lobe lift.
>
> Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> valve opening. Now turn the engine until the valve is at maximum lift and
> record that. (.450 for my example). Rotate the engine until the valve comes
> down to .075 lift again and record that number (10 ATDC for my example). You
> can now determine the intake lobe and where it is reaching peak lift. Take
> the BBDC number, add 180, and add the ABDC number to get 230. This is your
> duration at .050 tappet lift. To determine the lobe center angle, divide the
> duration in half (115) and "add" that to your exhaust opening point. (40 deg
> BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> peak lift at 115 degrees BTDC.
>
> The last thing you need to determine is the lobe separation angle. This is
> simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> is the split betwen the lobes. You can also figure out that the cam is
> installed 5 deg advanced by subtracting the lobe separation angle from the
> intake lobe centerline, or 110-105.
>
> Now that I typed all of this, I see it may be easier to pop the rear cam
> plug out of the block and see if there is a part number there ;-). Many of
> the manufacturers put the number on the back, but some put the number on the
> face where the timing gear sits, so this is a bit of a crap shoot.
>
> Chris
God Bless America, ßill O|||||||O
mailto:--------------------
c wrote:
>
> You can do it and get pretty close Mike. The important numbers are how many
> degrees the LIFTER is above .050 lift. This is the industry standard for
> measuring camshaft duration. Advertised duration measurement methods vary
> between manufacturers, so I would be leery about measuring how many degrees
> the lifter is above zero lift. Some cam companies use a small amount of the
> lift to act as lifter preload, especially for hydraulic cams.
>
> To measure the cam, it is best to have access to the lifter with a dial
> indicator, but you can get close with a hydralic one. You can also do the
> lift measurement at the valve, but then you are reling on the rocker arm
> ratio being correct, and you are also assuming that there is no part
> deflection anywhere.
>
> Anyway, the recommended way to do this is with a cam degree wheel. Basically
> it is the protractor you talked about using, but is calibrated a full 360
> degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> degree wheel, this is what it is:
> http://static.summitracing.com/globa...e/mrg-1570.jpg
>
> The pro engine builders use a very large diameter wheel to get their
> camshafts degreed in as close as possible.
>
> Once you have something like this, you can rig up some kind of a pointer for
> the wheel. I used to use a piece of a metal coat hanger and bend it to
> shape. For your purposes this will be plenty accurate. Now you need a dial
> indicator to measure the lift at the valve or at the lifter. If you do it at
> the valve, you need to know the rocker arm ratio for your engine. I will
> assume for my explanation that it is 1.5. If you are meauring the valve lift
> you will need to turn the engine in its normal rotation and take a reading
> on the degree wheel when the valve reaches .075 lift. You could crudely do
> this with a dial caliper as well by meauring from the top of the valve
> spring retainer to the valve spring seat on the head.
>
> Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> Now turn the engine until the valve is at maximum lift and record that.
> (.450 for my example). Rotate the engine until the valve comes down to .075
> lift again and record that number (25 ABDC for my example). You can now
> determine the intake lobe and where it is reaching peak lift. Take the BTDC
> number, add 180, and add the ABDC number to get 220. This is your duration
> at .050 tappet lift. To determine the lobe center angle, divide the duration
> in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> ratio, so .450/1.5 = .300 lobe lift.
>
> Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> valve opening. Now turn the engine until the valve is at maximum lift and
> record that. (.450 for my example). Rotate the engine until the valve comes
> down to .075 lift again and record that number (10 ATDC for my example). You
> can now determine the intake lobe and where it is reaching peak lift. Take
> the BBDC number, add 180, and add the ABDC number to get 230. This is your
> duration at .050 tappet lift. To determine the lobe center angle, divide the
> duration in half (115) and "add" that to your exhaust opening point. (40 deg
> BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> peak lift at 115 degrees BTDC.
>
> The last thing you need to determine is the lobe separation angle. This is
> simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> is the split betwen the lobes. You can also figure out that the cam is
> installed 5 deg advanced by subtracting the lobe separation angle from the
> intake lobe centerline, or 110-105.
>
> Now that I typed all of this, I see it may be easier to pop the rear cam
> plug out of the block and see if there is a part number there ;-). Many of
> the manufacturers put the number on the back, but some put the number on the
> face where the timing gear sits, so this is a bit of a crap shoot.
>
> Chris
05-22-2004, 02:26 AM
#32
Guest
Posts: n/a
Re: How can I tell what cam is in my old 86 4.2?
http://www.----------.com/IskyRR1000.jpg
God Bless America, ßill O|||||||O
mailto:--------------------
c wrote:
>
> You can do it and get pretty close Mike. The important numbers are how many
> degrees the LIFTER is above .050 lift. This is the industry standard for
> measuring camshaft duration. Advertised duration measurement methods vary
> between manufacturers, so I would be leery about measuring how many degrees
> the lifter is above zero lift. Some cam companies use a small amount of the
> lift to act as lifter preload, especially for hydraulic cams.
>
> To measure the cam, it is best to have access to the lifter with a dial
> indicator, but you can get close with a hydralic one. You can also do the
> lift measurement at the valve, but then you are reling on the rocker arm
> ratio being correct, and you are also assuming that there is no part
> deflection anywhere.
>
> Anyway, the recommended way to do this is with a cam degree wheel. Basically
> it is the protractor you talked about using, but is calibrated a full 360
> degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> degree wheel, this is what it is:
> http://static.summitracing.com/globa...e/mrg-1570.jpg
>
> The pro engine builders use a very large diameter wheel to get their
> camshafts degreed in as close as possible.
>
> Once you have something like this, you can rig up some kind of a pointer for
> the wheel. I used to use a piece of a metal coat hanger and bend it to
> shape. For your purposes this will be plenty accurate. Now you need a dial
> indicator to measure the lift at the valve or at the lifter. If you do it at
> the valve, you need to know the rocker arm ratio for your engine. I will
> assume for my explanation that it is 1.5. If you are meauring the valve lift
> you will need to turn the engine in its normal rotation and take a reading
> on the degree wheel when the valve reaches .075 lift. You could crudely do
> this with a dial caliper as well by meauring from the top of the valve
> spring retainer to the valve spring seat on the head.
>
> Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> Now turn the engine until the valve is at maximum lift and record that.
> (.450 for my example). Rotate the engine until the valve comes down to .075
> lift again and record that number (25 ABDC for my example). You can now
> determine the intake lobe and where it is reaching peak lift. Take the BTDC
> number, add 180, and add the ABDC number to get 220. This is your duration
> at .050 tappet lift. To determine the lobe center angle, divide the duration
> in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> ratio, so .450/1.5 = .300 lobe lift.
>
> Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> valve opening. Now turn the engine until the valve is at maximum lift and
> record that. (.450 for my example). Rotate the engine until the valve comes
> down to .075 lift again and record that number (10 ATDC for my example). You
> can now determine the intake lobe and where it is reaching peak lift. Take
> the BBDC number, add 180, and add the ABDC number to get 230. This is your
> duration at .050 tappet lift. To determine the lobe center angle, divide the
> duration in half (115) and "add" that to your exhaust opening point. (40 deg
> BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> peak lift at 115 degrees BTDC.
>
> The last thing you need to determine is the lobe separation angle. This is
> simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> is the split betwen the lobes. You can also figure out that the cam is
> installed 5 deg advanced by subtracting the lobe separation angle from the
> intake lobe centerline, or 110-105.
>
> Now that I typed all of this, I see it may be easier to pop the rear cam
> plug out of the block and see if there is a part number there ;-). Many of
> the manufacturers put the number on the back, but some put the number on the
> face where the timing gear sits, so this is a bit of a crap shoot.
>
> Chris
God Bless America, ßill O|||||||O
mailto:--------------------
c wrote:
>
> You can do it and get pretty close Mike. The important numbers are how many
> degrees the LIFTER is above .050 lift. This is the industry standard for
> measuring camshaft duration. Advertised duration measurement methods vary
> between manufacturers, so I would be leery about measuring how many degrees
> the lifter is above zero lift. Some cam companies use a small amount of the
> lift to act as lifter preload, especially for hydraulic cams.
>
> To measure the cam, it is best to have access to the lifter with a dial
> indicator, but you can get close with a hydralic one. You can also do the
> lift measurement at the valve, but then you are reling on the rocker arm
> ratio being correct, and you are also assuming that there is no part
> deflection anywhere.
>
> Anyway, the recommended way to do this is with a cam degree wheel. Basically
> it is the protractor you talked about using, but is calibrated a full 360
> degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> degree wheel, this is what it is:
> http://static.summitracing.com/globa...e/mrg-1570.jpg
>
> The pro engine builders use a very large diameter wheel to get their
> camshafts degreed in as close as possible.
>
> Once you have something like this, you can rig up some kind of a pointer for
> the wheel. I used to use a piece of a metal coat hanger and bend it to
> shape. For your purposes this will be plenty accurate. Now you need a dial
> indicator to measure the lift at the valve or at the lifter. If you do it at
> the valve, you need to know the rocker arm ratio for your engine. I will
> assume for my explanation that it is 1.5. If you are meauring the valve lift
> you will need to turn the engine in its normal rotation and take a reading
> on the degree wheel when the valve reaches .075 lift. You could crudely do
> this with a dial caliper as well by meauring from the top of the valve
> spring retainer to the valve spring seat on the head.
>
> Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> Now turn the engine until the valve is at maximum lift and record that.
> (.450 for my example). Rotate the engine until the valve comes down to .075
> lift again and record that number (25 ABDC for my example). You can now
> determine the intake lobe and where it is reaching peak lift. Take the BTDC
> number, add 180, and add the ABDC number to get 220. This is your duration
> at .050 tappet lift. To determine the lobe center angle, divide the duration
> in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> ratio, so .450/1.5 = .300 lobe lift.
>
> Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> valve opening. Now turn the engine until the valve is at maximum lift and
> record that. (.450 for my example). Rotate the engine until the valve comes
> down to .075 lift again and record that number (10 ATDC for my example). You
> can now determine the intake lobe and where it is reaching peak lift. Take
> the BBDC number, add 180, and add the ABDC number to get 230. This is your
> duration at .050 tappet lift. To determine the lobe center angle, divide the
> duration in half (115) and "add" that to your exhaust opening point. (40 deg
> BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> peak lift at 115 degrees BTDC.
>
> The last thing you need to determine is the lobe separation angle. This is
> simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> is the split betwen the lobes. You can also figure out that the cam is
> installed 5 deg advanced by subtracting the lobe separation angle from the
> intake lobe centerline, or 110-105.
>
> Now that I typed all of this, I see it may be easier to pop the rear cam
> plug out of the block and see if there is a part number there ;-). Many of
> the manufacturers put the number on the back, but some put the number on the
> face where the timing gear sits, so this is a bit of a crap shoot.
>
> Chris
05-22-2004, 02:26 AM
#33
Guest
Posts: n/a
Re: How can I tell what cam is in my old 86 4.2?
http://www.----------.com/IskyRR1000.jpg
God Bless America, ßill O|||||||O
mailto:--------------------
c wrote:
>
> You can do it and get pretty close Mike. The important numbers are how many
> degrees the LIFTER is above .050 lift. This is the industry standard for
> measuring camshaft duration. Advertised duration measurement methods vary
> between manufacturers, so I would be leery about measuring how many degrees
> the lifter is above zero lift. Some cam companies use a small amount of the
> lift to act as lifter preload, especially for hydraulic cams.
>
> To measure the cam, it is best to have access to the lifter with a dial
> indicator, but you can get close with a hydralic one. You can also do the
> lift measurement at the valve, but then you are reling on the rocker arm
> ratio being correct, and you are also assuming that there is no part
> deflection anywhere.
>
> Anyway, the recommended way to do this is with a cam degree wheel. Basically
> it is the protractor you talked about using, but is calibrated a full 360
> degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> degree wheel, this is what it is:
> http://static.summitracing.com/globa...e/mrg-1570.jpg
>
> The pro engine builders use a very large diameter wheel to get their
> camshafts degreed in as close as possible.
>
> Once you have something like this, you can rig up some kind of a pointer for
> the wheel. I used to use a piece of a metal coat hanger and bend it to
> shape. For your purposes this will be plenty accurate. Now you need a dial
> indicator to measure the lift at the valve or at the lifter. If you do it at
> the valve, you need to know the rocker arm ratio for your engine. I will
> assume for my explanation that it is 1.5. If you are meauring the valve lift
> you will need to turn the engine in its normal rotation and take a reading
> on the degree wheel when the valve reaches .075 lift. You could crudely do
> this with a dial caliper as well by meauring from the top of the valve
> spring retainer to the valve spring seat on the head.
>
> Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> Now turn the engine until the valve is at maximum lift and record that.
> (.450 for my example). Rotate the engine until the valve comes down to .075
> lift again and record that number (25 ABDC for my example). You can now
> determine the intake lobe and where it is reaching peak lift. Take the BTDC
> number, add 180, and add the ABDC number to get 220. This is your duration
> at .050 tappet lift. To determine the lobe center angle, divide the duration
> in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> ratio, so .450/1.5 = .300 lobe lift.
>
> Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> valve opening. Now turn the engine until the valve is at maximum lift and
> record that. (.450 for my example). Rotate the engine until the valve comes
> down to .075 lift again and record that number (10 ATDC for my example). You
> can now determine the intake lobe and where it is reaching peak lift. Take
> the BBDC number, add 180, and add the ABDC number to get 230. This is your
> duration at .050 tappet lift. To determine the lobe center angle, divide the
> duration in half (115) and "add" that to your exhaust opening point. (40 deg
> BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> peak lift at 115 degrees BTDC.
>
> The last thing you need to determine is the lobe separation angle. This is
> simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> is the split betwen the lobes. You can also figure out that the cam is
> installed 5 deg advanced by subtracting the lobe separation angle from the
> intake lobe centerline, or 110-105.
>
> Now that I typed all of this, I see it may be easier to pop the rear cam
> plug out of the block and see if there is a part number there ;-). Many of
> the manufacturers put the number on the back, but some put the number on the
> face where the timing gear sits, so this is a bit of a crap shoot.
>
> Chris
God Bless America, ßill O|||||||O
mailto:--------------------
c wrote:
>
> You can do it and get pretty close Mike. The important numbers are how many
> degrees the LIFTER is above .050 lift. This is the industry standard for
> measuring camshaft duration. Advertised duration measurement methods vary
> between manufacturers, so I would be leery about measuring how many degrees
> the lifter is above zero lift. Some cam companies use a small amount of the
> lift to act as lifter preload, especially for hydraulic cams.
>
> To measure the cam, it is best to have access to the lifter with a dial
> indicator, but you can get close with a hydralic one. You can also do the
> lift measurement at the valve, but then you are reling on the rocker arm
> ratio being correct, and you are also assuming that there is no part
> deflection anywhere.
>
> Anyway, the recommended way to do this is with a cam degree wheel. Basically
> it is the protractor you talked about using, but is calibrated a full 360
> degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> degree wheel, this is what it is:
> http://static.summitracing.com/globa...e/mrg-1570.jpg
>
> The pro engine builders use a very large diameter wheel to get their
> camshafts degreed in as close as possible.
>
> Once you have something like this, you can rig up some kind of a pointer for
> the wheel. I used to use a piece of a metal coat hanger and bend it to
> shape. For your purposes this will be plenty accurate. Now you need a dial
> indicator to measure the lift at the valve or at the lifter. If you do it at
> the valve, you need to know the rocker arm ratio for your engine. I will
> assume for my explanation that it is 1.5. If you are meauring the valve lift
> you will need to turn the engine in its normal rotation and take a reading
> on the degree wheel when the valve reaches .075 lift. You could crudely do
> this with a dial caliper as well by meauring from the top of the valve
> spring retainer to the valve spring seat on the head.
>
> Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> Now turn the engine until the valve is at maximum lift and record that.
> (.450 for my example). Rotate the engine until the valve comes down to .075
> lift again and record that number (25 ABDC for my example). You can now
> determine the intake lobe and where it is reaching peak lift. Take the BTDC
> number, add 180, and add the ABDC number to get 220. This is your duration
> at .050 tappet lift. To determine the lobe center angle, divide the duration
> in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> ratio, so .450/1.5 = .300 lobe lift.
>
> Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> valve opening. Now turn the engine until the valve is at maximum lift and
> record that. (.450 for my example). Rotate the engine until the valve comes
> down to .075 lift again and record that number (10 ATDC for my example). You
> can now determine the intake lobe and where it is reaching peak lift. Take
> the BBDC number, add 180, and add the ABDC number to get 230. This is your
> duration at .050 tappet lift. To determine the lobe center angle, divide the
> duration in half (115) and "add" that to your exhaust opening point. (40 deg
> BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> peak lift at 115 degrees BTDC.
>
> The last thing you need to determine is the lobe separation angle. This is
> simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> is the split betwen the lobes. You can also figure out that the cam is
> installed 5 deg advanced by subtracting the lobe separation angle from the
> intake lobe centerline, or 110-105.
>
> Now that I typed all of this, I see it may be easier to pop the rear cam
> plug out of the block and see if there is a part number there ;-). Many of
> the manufacturers put the number on the back, but some put the number on the
> face where the timing gear sits, so this is a bit of a crap shoot.
>
> Chris
05-22-2004, 02:36 AM
#34
Guest
Posts: n/a
Re: How can I tell what cam is in my old 86 4.2?
Cool, that's the back side?
Mike
"L.W.(ßill) ------ III" wrote:
>
> http://www.----------.com/IskyRR1000.jpg
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> c wrote:
> >
> > You can do it and get pretty close Mike. The important numbers are how many
> > degrees the LIFTER is above .050 lift. This is the industry standard for
> > measuring camshaft duration. Advertised duration measurement methods vary
> > between manufacturers, so I would be leery about measuring how many degrees
> > the lifter is above zero lift. Some cam companies use a small amount of the
> > lift to act as lifter preload, especially for hydraulic cams.
> >
> > To measure the cam, it is best to have access to the lifter with a dial
> > indicator, but you can get close with a hydralic one. You can also do the
> > lift measurement at the valve, but then you are reling on the rocker arm
> > ratio being correct, and you are also assuming that there is no part
> > deflection anywhere.
> >
> > Anyway, the recommended way to do this is with a cam degree wheel. Basically
> > it is the protractor you talked about using, but is calibrated a full 360
> > degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> > degree wheel, this is what it is:
> > http://static.summitracing.com/globa...e/mrg-1570.jpg
> >
> > The pro engine builders use a very large diameter wheel to get their
> > camshafts degreed in as close as possible.
> >
> > Once you have something like this, you can rig up some kind of a pointer for
> > the wheel. I used to use a piece of a metal coat hanger and bend it to
> > shape. For your purposes this will be plenty accurate. Now you need a dial
> > indicator to measure the lift at the valve or at the lifter. If you do it at
> > the valve, you need to know the rocker arm ratio for your engine. I will
> > assume for my explanation that it is 1.5. If you are meauring the valve lift
> > you will need to turn the engine in its normal rotation and take a reading
> > on the degree wheel when the valve reaches .075 lift. You could crudely do
> > this with a dial caliper as well by meauring from the top of the valve
> > spring retainer to the valve spring seat on the head.
> >
> > Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> > Now turn the engine until the valve is at maximum lift and record that.
> > (.450 for my example). Rotate the engine until the valve comes down to .075
> > lift again and record that number (25 ABDC for my example). You can now
> > determine the intake lobe and where it is reaching peak lift. Take the BTDC
> > number, add 180, and add the ABDC number to get 220. This is your duration
> > at .050 tappet lift. To determine the lobe center angle, divide the duration
> > in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> > rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> > 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> > ratio, so .450/1.5 = .300 lobe lift.
> >
> > Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> > valve opening. Now turn the engine until the valve is at maximum lift and
> > record that. (.450 for my example). Rotate the engine until the valve comes
> > down to .075 lift again and record that number (10 ATDC for my example). You
> > can now determine the intake lobe and where it is reaching peak lift. Take
> > the BBDC number, add 180, and add the ABDC number to get 230. This is your
> > duration at .050 tappet lift. To determine the lobe center angle, divide the
> > duration in half (115) and "add" that to your exhaust opening point. (40 deg
> > BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> > peak lift at 115 degrees BTDC.
> >
> > The last thing you need to determine is the lobe separation angle. This is
> > simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> > is the split betwen the lobes. You can also figure out that the cam is
> > installed 5 deg advanced by subtracting the lobe separation angle from the
> > intake lobe centerline, or 110-105.
> >
> > Now that I typed all of this, I see it may be easier to pop the rear cam
> > plug out of the block and see if there is a part number there ;-). Many of
> > the manufacturers put the number on the back, but some put the number on the
> > face where the timing gear sits, so this is a bit of a crap shoot.
> >
> > Chris
Mike
"L.W.(ßill) ------ III" wrote:
>
> http://www.----------.com/IskyRR1000.jpg
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> c wrote:
> >
> > You can do it and get pretty close Mike. The important numbers are how many
> > degrees the LIFTER is above .050 lift. This is the industry standard for
> > measuring camshaft duration. Advertised duration measurement methods vary
> > between manufacturers, so I would be leery about measuring how many degrees
> > the lifter is above zero lift. Some cam companies use a small amount of the
> > lift to act as lifter preload, especially for hydraulic cams.
> >
> > To measure the cam, it is best to have access to the lifter with a dial
> > indicator, but you can get close with a hydralic one. You can also do the
> > lift measurement at the valve, but then you are reling on the rocker arm
> > ratio being correct, and you are also assuming that there is no part
> > deflection anywhere.
> >
> > Anyway, the recommended way to do this is with a cam degree wheel. Basically
> > it is the protractor you talked about using, but is calibrated a full 360
> > degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> > degree wheel, this is what it is:
> > http://static.summitracing.com/globa...e/mrg-1570.jpg
> >
> > The pro engine builders use a very large diameter wheel to get their
> > camshafts degreed in as close as possible.
> >
> > Once you have something like this, you can rig up some kind of a pointer for
> > the wheel. I used to use a piece of a metal coat hanger and bend it to
> > shape. For your purposes this will be plenty accurate. Now you need a dial
> > indicator to measure the lift at the valve or at the lifter. If you do it at
> > the valve, you need to know the rocker arm ratio for your engine. I will
> > assume for my explanation that it is 1.5. If you are meauring the valve lift
> > you will need to turn the engine in its normal rotation and take a reading
> > on the degree wheel when the valve reaches .075 lift. You could crudely do
> > this with a dial caliper as well by meauring from the top of the valve
> > spring retainer to the valve spring seat on the head.
> >
> > Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> > Now turn the engine until the valve is at maximum lift and record that.
> > (.450 for my example). Rotate the engine until the valve comes down to .075
> > lift again and record that number (25 ABDC for my example). You can now
> > determine the intake lobe and where it is reaching peak lift. Take the BTDC
> > number, add 180, and add the ABDC number to get 220. This is your duration
> > at .050 tappet lift. To determine the lobe center angle, divide the duration
> > in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> > rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> > 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> > ratio, so .450/1.5 = .300 lobe lift.
> >
> > Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> > valve opening. Now turn the engine until the valve is at maximum lift and
> > record that. (.450 for my example). Rotate the engine until the valve comes
> > down to .075 lift again and record that number (10 ATDC for my example). You
> > can now determine the intake lobe and where it is reaching peak lift. Take
> > the BBDC number, add 180, and add the ABDC number to get 230. This is your
> > duration at .050 tappet lift. To determine the lobe center angle, divide the
> > duration in half (115) and "add" that to your exhaust opening point. (40 deg
> > BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> > peak lift at 115 degrees BTDC.
> >
> > The last thing you need to determine is the lobe separation angle. This is
> > simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> > is the split betwen the lobes. You can also figure out that the cam is
> > installed 5 deg advanced by subtracting the lobe separation angle from the
> > intake lobe centerline, or 110-105.
> >
> > Now that I typed all of this, I see it may be easier to pop the rear cam
> > plug out of the block and see if there is a part number there ;-). Many of
> > the manufacturers put the number on the back, but some put the number on the
> > face where the timing gear sits, so this is a bit of a crap shoot.
> >
> > Chris
05-22-2004, 02:36 AM
#35
Guest
Posts: n/a
Re: How can I tell what cam is in my old 86 4.2?
Cool, that's the back side?
Mike
"L.W.(ßill) ------ III" wrote:
>
> http://www.----------.com/IskyRR1000.jpg
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> c wrote:
> >
> > You can do it and get pretty close Mike. The important numbers are how many
> > degrees the LIFTER is above .050 lift. This is the industry standard for
> > measuring camshaft duration. Advertised duration measurement methods vary
> > between manufacturers, so I would be leery about measuring how many degrees
> > the lifter is above zero lift. Some cam companies use a small amount of the
> > lift to act as lifter preload, especially for hydraulic cams.
> >
> > To measure the cam, it is best to have access to the lifter with a dial
> > indicator, but you can get close with a hydralic one. You can also do the
> > lift measurement at the valve, but then you are reling on the rocker arm
> > ratio being correct, and you are also assuming that there is no part
> > deflection anywhere.
> >
> > Anyway, the recommended way to do this is with a cam degree wheel. Basically
> > it is the protractor you talked about using, but is calibrated a full 360
> > degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> > degree wheel, this is what it is:
> > http://static.summitracing.com/globa...e/mrg-1570.jpg
> >
> > The pro engine builders use a very large diameter wheel to get their
> > camshafts degreed in as close as possible.
> >
> > Once you have something like this, you can rig up some kind of a pointer for
> > the wheel. I used to use a piece of a metal coat hanger and bend it to
> > shape. For your purposes this will be plenty accurate. Now you need a dial
> > indicator to measure the lift at the valve or at the lifter. If you do it at
> > the valve, you need to know the rocker arm ratio for your engine. I will
> > assume for my explanation that it is 1.5. If you are meauring the valve lift
> > you will need to turn the engine in its normal rotation and take a reading
> > on the degree wheel when the valve reaches .075 lift. You could crudely do
> > this with a dial caliper as well by meauring from the top of the valve
> > spring retainer to the valve spring seat on the head.
> >
> > Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> > Now turn the engine until the valve is at maximum lift and record that.
> > (.450 for my example). Rotate the engine until the valve comes down to .075
> > lift again and record that number (25 ABDC for my example). You can now
> > determine the intake lobe and where it is reaching peak lift. Take the BTDC
> > number, add 180, and add the ABDC number to get 220. This is your duration
> > at .050 tappet lift. To determine the lobe center angle, divide the duration
> > in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> > rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> > 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> > ratio, so .450/1.5 = .300 lobe lift.
> >
> > Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> > valve opening. Now turn the engine until the valve is at maximum lift and
> > record that. (.450 for my example). Rotate the engine until the valve comes
> > down to .075 lift again and record that number (10 ATDC for my example). You
> > can now determine the intake lobe and where it is reaching peak lift. Take
> > the BBDC number, add 180, and add the ABDC number to get 230. This is your
> > duration at .050 tappet lift. To determine the lobe center angle, divide the
> > duration in half (115) and "add" that to your exhaust opening point. (40 deg
> > BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> > peak lift at 115 degrees BTDC.
> >
> > The last thing you need to determine is the lobe separation angle. This is
> > simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> > is the split betwen the lobes. You can also figure out that the cam is
> > installed 5 deg advanced by subtracting the lobe separation angle from the
> > intake lobe centerline, or 110-105.
> >
> > Now that I typed all of this, I see it may be easier to pop the rear cam
> > plug out of the block and see if there is a part number there ;-). Many of
> > the manufacturers put the number on the back, but some put the number on the
> > face where the timing gear sits, so this is a bit of a crap shoot.
> >
> > Chris
Mike
"L.W.(ßill) ------ III" wrote:
>
> http://www.----------.com/IskyRR1000.jpg
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> c wrote:
> >
> > You can do it and get pretty close Mike. The important numbers are how many
> > degrees the LIFTER is above .050 lift. This is the industry standard for
> > measuring camshaft duration. Advertised duration measurement methods vary
> > between manufacturers, so I would be leery about measuring how many degrees
> > the lifter is above zero lift. Some cam companies use a small amount of the
> > lift to act as lifter preload, especially for hydraulic cams.
> >
> > To measure the cam, it is best to have access to the lifter with a dial
> > indicator, but you can get close with a hydralic one. You can also do the
> > lift measurement at the valve, but then you are reling on the rocker arm
> > ratio being correct, and you are also assuming that there is no part
> > deflection anywhere.
> >
> > Anyway, the recommended way to do this is with a cam degree wheel. Basically
> > it is the protractor you talked about using, but is calibrated a full 360
> > degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> > degree wheel, this is what it is:
> > http://static.summitracing.com/globa...e/mrg-1570.jpg
> >
> > The pro engine builders use a very large diameter wheel to get their
> > camshafts degreed in as close as possible.
> >
> > Once you have something like this, you can rig up some kind of a pointer for
> > the wheel. I used to use a piece of a metal coat hanger and bend it to
> > shape. For your purposes this will be plenty accurate. Now you need a dial
> > indicator to measure the lift at the valve or at the lifter. If you do it at
> > the valve, you need to know the rocker arm ratio for your engine. I will
> > assume for my explanation that it is 1.5. If you are meauring the valve lift
> > you will need to turn the engine in its normal rotation and take a reading
> > on the degree wheel when the valve reaches .075 lift. You could crudely do
> > this with a dial caliper as well by meauring from the top of the valve
> > spring retainer to the valve spring seat on the head.
> >
> > Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> > Now turn the engine until the valve is at maximum lift and record that.
> > (.450 for my example). Rotate the engine until the valve comes down to .075
> > lift again and record that number (25 ABDC for my example). You can now
> > determine the intake lobe and where it is reaching peak lift. Take the BTDC
> > number, add 180, and add the ABDC number to get 220. This is your duration
> > at .050 tappet lift. To determine the lobe center angle, divide the duration
> > in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> > rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> > 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> > ratio, so .450/1.5 = .300 lobe lift.
> >
> > Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> > valve opening. Now turn the engine until the valve is at maximum lift and
> > record that. (.450 for my example). Rotate the engine until the valve comes
> > down to .075 lift again and record that number (10 ATDC for my example). You
> > can now determine the intake lobe and where it is reaching peak lift. Take
> > the BBDC number, add 180, and add the ABDC number to get 230. This is your
> > duration at .050 tappet lift. To determine the lobe center angle, divide the
> > duration in half (115) and "add" that to your exhaust opening point. (40 deg
> > BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> > peak lift at 115 degrees BTDC.
> >
> > The last thing you need to determine is the lobe separation angle. This is
> > simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> > is the split betwen the lobes. You can also figure out that the cam is
> > installed 5 deg advanced by subtracting the lobe separation angle from the
> > intake lobe centerline, or 110-105.
> >
> > Now that I typed all of this, I see it may be easier to pop the rear cam
> > plug out of the block and see if there is a part number there ;-). Many of
> > the manufacturers put the number on the back, but some put the number on the
> > face where the timing gear sits, so this is a bit of a crap shoot.
> >
> > Chris
05-22-2004, 02:36 AM
#36
Guest
Posts: n/a
Re: How can I tell what cam is in my old 86 4.2?
Cool, that's the back side?
Mike
"L.W.(ßill) ------ III" wrote:
>
> http://www.----------.com/IskyRR1000.jpg
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> c wrote:
> >
> > You can do it and get pretty close Mike. The important numbers are how many
> > degrees the LIFTER is above .050 lift. This is the industry standard for
> > measuring camshaft duration. Advertised duration measurement methods vary
> > between manufacturers, so I would be leery about measuring how many degrees
> > the lifter is above zero lift. Some cam companies use a small amount of the
> > lift to act as lifter preload, especially for hydraulic cams.
> >
> > To measure the cam, it is best to have access to the lifter with a dial
> > indicator, but you can get close with a hydralic one. You can also do the
> > lift measurement at the valve, but then you are reling on the rocker arm
> > ratio being correct, and you are also assuming that there is no part
> > deflection anywhere.
> >
> > Anyway, the recommended way to do this is with a cam degree wheel. Basically
> > it is the protractor you talked about using, but is calibrated a full 360
> > degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> > degree wheel, this is what it is:
> > http://static.summitracing.com/globa...e/mrg-1570.jpg
> >
> > The pro engine builders use a very large diameter wheel to get their
> > camshafts degreed in as close as possible.
> >
> > Once you have something like this, you can rig up some kind of a pointer for
> > the wheel. I used to use a piece of a metal coat hanger and bend it to
> > shape. For your purposes this will be plenty accurate. Now you need a dial
> > indicator to measure the lift at the valve or at the lifter. If you do it at
> > the valve, you need to know the rocker arm ratio for your engine. I will
> > assume for my explanation that it is 1.5. If you are meauring the valve lift
> > you will need to turn the engine in its normal rotation and take a reading
> > on the degree wheel when the valve reaches .075 lift. You could crudely do
> > this with a dial caliper as well by meauring from the top of the valve
> > spring retainer to the valve spring seat on the head.
> >
> > Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> > Now turn the engine until the valve is at maximum lift and record that.
> > (.450 for my example). Rotate the engine until the valve comes down to .075
> > lift again and record that number (25 ABDC for my example). You can now
> > determine the intake lobe and where it is reaching peak lift. Take the BTDC
> > number, add 180, and add the ABDC number to get 220. This is your duration
> > at .050 tappet lift. To determine the lobe center angle, divide the duration
> > in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> > rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> > 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> > ratio, so .450/1.5 = .300 lobe lift.
> >
> > Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> > valve opening. Now turn the engine until the valve is at maximum lift and
> > record that. (.450 for my example). Rotate the engine until the valve comes
> > down to .075 lift again and record that number (10 ATDC for my example). You
> > can now determine the intake lobe and where it is reaching peak lift. Take
> > the BBDC number, add 180, and add the ABDC number to get 230. This is your
> > duration at .050 tappet lift. To determine the lobe center angle, divide the
> > duration in half (115) and "add" that to your exhaust opening point. (40 deg
> > BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> > peak lift at 115 degrees BTDC.
> >
> > The last thing you need to determine is the lobe separation angle. This is
> > simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> > is the split betwen the lobes. You can also figure out that the cam is
> > installed 5 deg advanced by subtracting the lobe separation angle from the
> > intake lobe centerline, or 110-105.
> >
> > Now that I typed all of this, I see it may be easier to pop the rear cam
> > plug out of the block and see if there is a part number there ;-). Many of
> > the manufacturers put the number on the back, but some put the number on the
> > face where the timing gear sits, so this is a bit of a crap shoot.
> >
> > Chris
Mike
"L.W.(ßill) ------ III" wrote:
>
> http://www.----------.com/IskyRR1000.jpg
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> c wrote:
> >
> > You can do it and get pretty close Mike. The important numbers are how many
> > degrees the LIFTER is above .050 lift. This is the industry standard for
> > measuring camshaft duration. Advertised duration measurement methods vary
> > between manufacturers, so I would be leery about measuring how many degrees
> > the lifter is above zero lift. Some cam companies use a small amount of the
> > lift to act as lifter preload, especially for hydraulic cams.
> >
> > To measure the cam, it is best to have access to the lifter with a dial
> > indicator, but you can get close with a hydralic one. You can also do the
> > lift measurement at the valve, but then you are reling on the rocker arm
> > ratio being correct, and you are also assuming that there is no part
> > deflection anywhere.
> >
> > Anyway, the recommended way to do this is with a cam degree wheel. Basically
> > it is the protractor you talked about using, but is calibrated a full 360
> > degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> > degree wheel, this is what it is:
> > http://static.summitracing.com/globa...e/mrg-1570.jpg
> >
> > The pro engine builders use a very large diameter wheel to get their
> > camshafts degreed in as close as possible.
> >
> > Once you have something like this, you can rig up some kind of a pointer for
> > the wheel. I used to use a piece of a metal coat hanger and bend it to
> > shape. For your purposes this will be plenty accurate. Now you need a dial
> > indicator to measure the lift at the valve or at the lifter. If you do it at
> > the valve, you need to know the rocker arm ratio for your engine. I will
> > assume for my explanation that it is 1.5. If you are meauring the valve lift
> > you will need to turn the engine in its normal rotation and take a reading
> > on the degree wheel when the valve reaches .075 lift. You could crudely do
> > this with a dial caliper as well by meauring from the top of the valve
> > spring retainer to the valve spring seat on the head.
> >
> > Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> > Now turn the engine until the valve is at maximum lift and record that.
> > (.450 for my example). Rotate the engine until the valve comes down to .075
> > lift again and record that number (25 ABDC for my example). You can now
> > determine the intake lobe and where it is reaching peak lift. Take the BTDC
> > number, add 180, and add the ABDC number to get 220. This is your duration
> > at .050 tappet lift. To determine the lobe center angle, divide the duration
> > in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> > rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> > 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> > ratio, so .450/1.5 = .300 lobe lift.
> >
> > Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> > valve opening. Now turn the engine until the valve is at maximum lift and
> > record that. (.450 for my example). Rotate the engine until the valve comes
> > down to .075 lift again and record that number (10 ATDC for my example). You
> > can now determine the intake lobe and where it is reaching peak lift. Take
> > the BBDC number, add 180, and add the ABDC number to get 230. This is your
> > duration at .050 tappet lift. To determine the lobe center angle, divide the
> > duration in half (115) and "add" that to your exhaust opening point. (40 deg
> > BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> > peak lift at 115 degrees BTDC.
> >
> > The last thing you need to determine is the lobe separation angle. This is
> > simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> > is the split betwen the lobes. You can also figure out that the cam is
> > installed 5 deg advanced by subtracting the lobe separation angle from the
> > intake lobe centerline, or 110-105.
> >
> > Now that I typed all of this, I see it may be easier to pop the rear cam
> > plug out of the block and see if there is a part number there ;-). Many of
> > the manufacturers put the number on the back, but some put the number on the
> > face where the timing gear sits, so this is a bit of a crap shoot.
> >
> > Chris
05-22-2004, 02:36 AM
#37
Guest
Posts: n/a
Re: How can I tell what cam is in my old 86 4.2?
Cool, that's the back side?
Mike
"L.W.(ßill) ------ III" wrote:
>
> http://www.----------.com/IskyRR1000.jpg
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> c wrote:
> >
> > You can do it and get pretty close Mike. The important numbers are how many
> > degrees the LIFTER is above .050 lift. This is the industry standard for
> > measuring camshaft duration. Advertised duration measurement methods vary
> > between manufacturers, so I would be leery about measuring how many degrees
> > the lifter is above zero lift. Some cam companies use a small amount of the
> > lift to act as lifter preload, especially for hydraulic cams.
> >
> > To measure the cam, it is best to have access to the lifter with a dial
> > indicator, but you can get close with a hydralic one. You can also do the
> > lift measurement at the valve, but then you are reling on the rocker arm
> > ratio being correct, and you are also assuming that there is no part
> > deflection anywhere.
> >
> > Anyway, the recommended way to do this is with a cam degree wheel. Basically
> > it is the protractor you talked about using, but is calibrated a full 360
> > degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> > degree wheel, this is what it is:
> > http://static.summitracing.com/globa...e/mrg-1570.jpg
> >
> > The pro engine builders use a very large diameter wheel to get their
> > camshafts degreed in as close as possible.
> >
> > Once you have something like this, you can rig up some kind of a pointer for
> > the wheel. I used to use a piece of a metal coat hanger and bend it to
> > shape. For your purposes this will be plenty accurate. Now you need a dial
> > indicator to measure the lift at the valve or at the lifter. If you do it at
> > the valve, you need to know the rocker arm ratio for your engine. I will
> > assume for my explanation that it is 1.5. If you are meauring the valve lift
> > you will need to turn the engine in its normal rotation and take a reading
> > on the degree wheel when the valve reaches .075 lift. You could crudely do
> > this with a dial caliper as well by meauring from the top of the valve
> > spring retainer to the valve spring seat on the head.
> >
> > Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> > Now turn the engine until the valve is at maximum lift and record that.
> > (.450 for my example). Rotate the engine until the valve comes down to .075
> > lift again and record that number (25 ABDC for my example). You can now
> > determine the intake lobe and where it is reaching peak lift. Take the BTDC
> > number, add 180, and add the ABDC number to get 220. This is your duration
> > at .050 tappet lift. To determine the lobe center angle, divide the duration
> > in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> > rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> > 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> > ratio, so .450/1.5 = .300 lobe lift.
> >
> > Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> > valve opening. Now turn the engine until the valve is at maximum lift and
> > record that. (.450 for my example). Rotate the engine until the valve comes
> > down to .075 lift again and record that number (10 ATDC for my example). You
> > can now determine the intake lobe and where it is reaching peak lift. Take
> > the BBDC number, add 180, and add the ABDC number to get 230. This is your
> > duration at .050 tappet lift. To determine the lobe center angle, divide the
> > duration in half (115) and "add" that to your exhaust opening point. (40 deg
> > BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> > peak lift at 115 degrees BTDC.
> >
> > The last thing you need to determine is the lobe separation angle. This is
> > simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> > is the split betwen the lobes. You can also figure out that the cam is
> > installed 5 deg advanced by subtracting the lobe separation angle from the
> > intake lobe centerline, or 110-105.
> >
> > Now that I typed all of this, I see it may be easier to pop the rear cam
> > plug out of the block and see if there is a part number there ;-). Many of
> > the manufacturers put the number on the back, but some put the number on the
> > face where the timing gear sits, so this is a bit of a crap shoot.
> >
> > Chris
Mike
"L.W.(ßill) ------ III" wrote:
>
> http://www.----------.com/IskyRR1000.jpg
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> c wrote:
> >
> > You can do it and get pretty close Mike. The important numbers are how many
> > degrees the LIFTER is above .050 lift. This is the industry standard for
> > measuring camshaft duration. Advertised duration measurement methods vary
> > between manufacturers, so I would be leery about measuring how many degrees
> > the lifter is above zero lift. Some cam companies use a small amount of the
> > lift to act as lifter preload, especially for hydraulic cams.
> >
> > To measure the cam, it is best to have access to the lifter with a dial
> > indicator, but you can get close with a hydralic one. You can also do the
> > lift measurement at the valve, but then you are reling on the rocker arm
> > ratio being correct, and you are also assuming that there is no part
> > deflection anywhere.
> >
> > Anyway, the recommended way to do this is with a cam degree wheel. Basically
> > it is the protractor you talked about using, but is calibrated a full 360
> > degrees. This bolts to the harmonic balancer. If youhaven't ever seen a
> > degree wheel, this is what it is:
> > http://static.summitracing.com/globa...e/mrg-1570.jpg
> >
> > The pro engine builders use a very large diameter wheel to get their
> > camshafts degreed in as close as possible.
> >
> > Once you have something like this, you can rig up some kind of a pointer for
> > the wheel. I used to use a piece of a metal coat hanger and bend it to
> > shape. For your purposes this will be plenty accurate. Now you need a dial
> > indicator to measure the lift at the valve or at the lifter. If you do it at
> > the valve, you need to know the rocker arm ratio for your engine. I will
> > assume for my explanation that it is 1.5. If you are meauring the valve lift
> > you will need to turn the engine in its normal rotation and take a reading
> > on the degree wheel when the valve reaches .075 lift. You could crudely do
> > this with a dial caliper as well by meauring from the top of the valve
> > spring retainer to the valve spring seat on the head.
> >
> > Record the reading on the wheel. I will use 5 degrees BTDC as an example.
> > Now turn the engine until the valve is at maximum lift and record that.
> > (.450 for my example). Rotate the engine until the valve comes down to .075
> > lift again and record that number (25 ABDC for my example). You can now
> > determine the intake lobe and where it is reaching peak lift. Take the BTDC
> > number, add 180, and add the ABDC number to get 220. This is your duration
> > at .050 tappet lift. To determine the lobe center angle, divide the duration
> > in half (110) and "add" that to your intake opening point. (5 deg BTDC +110
> > rotation = 105 deg ATDC) this would mean your cam lobe reaches peak lift at
> > 105 degrees ATDC. Cam lobe lift is simply valve lift divided by rocker
> > ratio, so .450/1.5 = .300 lobe lift.
> >
> > Repeat the procedure for the exhaust valve. I will use 40 degrees BBDC for
> > valve opening. Now turn the engine until the valve is at maximum lift and
> > record that. (.450 for my example). Rotate the engine until the valve comes
> > down to .075 lift again and record that number (10 ATDC for my example). You
> > can now determine the intake lobe and where it is reaching peak lift. Take
> > the BBDC number, add 180, and add the ABDC number to get 230. This is your
> > duration at .050 tappet lift. To determine the lobe center angle, divide the
> > duration in half (115) and "add" that to your exhaust opening point. (40 deg
> > BBDC +115 rotation = 115 deg BTDC) this would mean your cam lobe reaches
> > peak lift at 115 degrees BTDC.
> >
> > The last thing you need to determine is the lobe separation angle. This is
> > simply the average of the 2 lobe center angles, so (105 + 115)/2 = 110. This
> > is the split betwen the lobes. You can also figure out that the cam is
> > installed 5 deg advanced by subtracting the lobe separation angle from the
> > intake lobe centerline, or 110-105.
> >
> > Now that I typed all of this, I see it may be easier to pop the rear cam
> > plug out of the block and see if there is a part number there ;-). Many of
> > the manufacturers put the number on the back, but some put the number on the
> > face where the timing gear sits, so this is a bit of a crap shoot.
> >
> > Chris
05-22-2004, 02:51 AM
#38
Guest
Posts: n/a
Re: How can I tell what cam is in my old 86 4.2?
What some people's dream wheel looks like:
http://www.iskycams.com/engine_templ...7&engine_id=20
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> I am misleading there a bit.
>
> It is a US Jeep with the speedo in miles. The cat isn't needed up here,
> don't know what it had original.
>
> Mike
http://www.iskycams.com/engine_templ...7&engine_id=20
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> I am misleading there a bit.
>
> It is a US Jeep with the speedo in miles. The cat isn't needed up here,
> don't know what it had original.
>
> Mike
05-22-2004, 02:51 AM
#39
Guest
Posts: n/a
Re: How can I tell what cam is in my old 86 4.2?
What some people's dream wheel looks like:
http://www.iskycams.com/engine_templ...7&engine_id=20
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> I am misleading there a bit.
>
> It is a US Jeep with the speedo in miles. The cat isn't needed up here,
> don't know what it had original.
>
> Mike
http://www.iskycams.com/engine_templ...7&engine_id=20
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> I am misleading there a bit.
>
> It is a US Jeep with the speedo in miles. The cat isn't needed up here,
> don't know what it had original.
>
> Mike
05-22-2004, 02:51 AM
#40
Guest
Posts: n/a
Re: How can I tell what cam is in my old 86 4.2?
What some people's dream wheel looks like:
http://www.iskycams.com/engine_templ...7&engine_id=20
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> I am misleading there a bit.
>
> It is a US Jeep with the speedo in miles. The cat isn't needed up here,
> don't know what it had original.
>
> Mike
http://www.iskycams.com/engine_templ...7&engine_id=20
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> I am misleading there a bit.
>
> It is a US Jeep with the speedo in miles. The cat isn't needed up here,
> don't know what it had original.
>
> Mike