CJ5 misfires at high RPM/hard acceleration
07-16-2007, 03:41 PM
#61
Guest
Posts: n/a
Re: CJ5 misfires at high RPM/hard acceleration
SnoMan wrote:
> On Mon, 16 Jul 2007 10:15:36 -0400, Mike Romain <romainm@sympatico.ca>
> wrote:
>
>> 'All' the old Jeep engines 'I' personally have seen (and read about
>> 'many') will 'NOT' run on Bosch platinum plugs.
>>
>> They foul up almost immediately.
>>
>> I would change those before doing anything else and put proper Champion
>> truck plugs back into it.
>
> Where do you get this BS at?????
'I' actually have worked on Jeep engines and 'fixed' a whole bunch with
fouling Bosch plugs.
Lots of folks get suckered by the hype and change out the Champion plugs.
If you Google this group, you will find the the older Jeep engines will
'not' run on Bosch plugs, period.
It is well documented and a very common cause of fouling plugs.
It is also a very common topic on other groups that deal with American
engines.
Bosch might have the heat ranges totally screwed in their book for Jeep
engines, who knows, but they don't work.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
> On Mon, 16 Jul 2007 10:15:36 -0400, Mike Romain <romainm@sympatico.ca>
> wrote:
>
>> 'All' the old Jeep engines 'I' personally have seen (and read about
>> 'many') will 'NOT' run on Bosch platinum plugs.
>>
>> They foul up almost immediately.
>>
>> I would change those before doing anything else and put proper Champion
>> truck plugs back into it.
>
> Where do you get this BS at?????
'I' actually have worked on Jeep engines and 'fixed' a whole bunch with
fouling Bosch plugs.
Lots of folks get suckered by the hype and change out the Champion plugs.
If you Google this group, you will find the the older Jeep engines will
'not' run on Bosch plugs, period.
It is well documented and a very common cause of fouling plugs.
It is also a very common topic on other groups that deal with American
engines.
Bosch might have the heat ranges totally screwed in their book for Jeep
engines, who knows, but they don't work.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
07-16-2007, 08:13 PM
#62
Guest
Posts: n/a
Re: CJ5 misfires at high RPM/hard acceleration
I have another question if anyone is familiar with AMC engines. If
the distributor & oil pump gears were removed at the same time, does
it matter which way they go back in? I assume you can only be 180
degrees off, but the oil pump drive gear has turned relative to where
it was when the distributor was removed, which in turn means that the
distributor's actual drive gear will be in a different spot from when
it was removed (if that makes any sense). Does this matter, or is
irrelevant other than deciding the initial position of the distributor
& cap? I assume that it wont matter, & can just be corrected by
moving the distributor whichever way is required to get the timing
back on track after the distributor is dropped back in, but it was one
more thing that I remember doing after I had my symptoms show up,
which may have been present merely from the bad vacuum advance. I'm
just afraid I may have caused more problems by doing this.
I ordered a new carb & will pick up some new plugs to rule that out
hopefully tomorrow. My timing light is just a basic light with no
dials & I don't have access to anything else unfortunately. It's very
hard to see the mark on the balancer after I get about 25 degrees
advance with my current light. I think I may take a stab at looking
to the timing chain too if the new carb & plugs don't make a
difference unless you guys definitely do not think it's the chain. If
the answer to my previous question about the distributor & oil pump
drive gears is yes, how would I go about putting it back in
correctly? I assume I put the engine at TDC on the compression stroke
for cylinder 1, then make sure the cam & crank sprocket indicators
line up vertically, but is there any specific way the distributor will
need to go in relative to the oil pump drive gear or the cam shaft?
It seems as if there should be some kind of line or marking on the
distributor telling you which way it needs to be dropped in if that's
the case.
Thanks again for everyones help, it's greatly appreciated.
-Matt
the distributor & oil pump gears were removed at the same time, does
it matter which way they go back in? I assume you can only be 180
degrees off, but the oil pump drive gear has turned relative to where
it was when the distributor was removed, which in turn means that the
distributor's actual drive gear will be in a different spot from when
it was removed (if that makes any sense). Does this matter, or is
irrelevant other than deciding the initial position of the distributor
& cap? I assume that it wont matter, & can just be corrected by
moving the distributor whichever way is required to get the timing
back on track after the distributor is dropped back in, but it was one
more thing that I remember doing after I had my symptoms show up,
which may have been present merely from the bad vacuum advance. I'm
just afraid I may have caused more problems by doing this.
I ordered a new carb & will pick up some new plugs to rule that out
hopefully tomorrow. My timing light is just a basic light with no
dials & I don't have access to anything else unfortunately. It's very
hard to see the mark on the balancer after I get about 25 degrees
advance with my current light. I think I may take a stab at looking
to the timing chain too if the new carb & plugs don't make a
difference unless you guys definitely do not think it's the chain. If
the answer to my previous question about the distributor & oil pump
drive gears is yes, how would I go about putting it back in
correctly? I assume I put the engine at TDC on the compression stroke
for cylinder 1, then make sure the cam & crank sprocket indicators
line up vertically, but is there any specific way the distributor will
need to go in relative to the oil pump drive gear or the cam shaft?
It seems as if there should be some kind of line or marking on the
distributor telling you which way it needs to be dropped in if that's
the case.
Thanks again for everyones help, it's greatly appreciated.
-Matt
07-16-2007, 08:13 PM
#63
Guest
Posts: n/a
Re: CJ5 misfires at high RPM/hard acceleration
I have another question if anyone is familiar with AMC engines. If
the distributor & oil pump gears were removed at the same time, does
it matter which way they go back in? I assume you can only be 180
degrees off, but the oil pump drive gear has turned relative to where
it was when the distributor was removed, which in turn means that the
distributor's actual drive gear will be in a different spot from when
it was removed (if that makes any sense). Does this matter, or is
irrelevant other than deciding the initial position of the distributor
& cap? I assume that it wont matter, & can just be corrected by
moving the distributor whichever way is required to get the timing
back on track after the distributor is dropped back in, but it was one
more thing that I remember doing after I had my symptoms show up,
which may have been present merely from the bad vacuum advance. I'm
just afraid I may have caused more problems by doing this.
I ordered a new carb & will pick up some new plugs to rule that out
hopefully tomorrow. My timing light is just a basic light with no
dials & I don't have access to anything else unfortunately. It's very
hard to see the mark on the balancer after I get about 25 degrees
advance with my current light. I think I may take a stab at looking
to the timing chain too if the new carb & plugs don't make a
difference unless you guys definitely do not think it's the chain. If
the answer to my previous question about the distributor & oil pump
drive gears is yes, how would I go about putting it back in
correctly? I assume I put the engine at TDC on the compression stroke
for cylinder 1, then make sure the cam & crank sprocket indicators
line up vertically, but is there any specific way the distributor will
need to go in relative to the oil pump drive gear or the cam shaft?
It seems as if there should be some kind of line or marking on the
distributor telling you which way it needs to be dropped in if that's
the case.
Thanks again for everyones help, it's greatly appreciated.
-Matt
the distributor & oil pump gears were removed at the same time, does
it matter which way they go back in? I assume you can only be 180
degrees off, but the oil pump drive gear has turned relative to where
it was when the distributor was removed, which in turn means that the
distributor's actual drive gear will be in a different spot from when
it was removed (if that makes any sense). Does this matter, or is
irrelevant other than deciding the initial position of the distributor
& cap? I assume that it wont matter, & can just be corrected by
moving the distributor whichever way is required to get the timing
back on track after the distributor is dropped back in, but it was one
more thing that I remember doing after I had my symptoms show up,
which may have been present merely from the bad vacuum advance. I'm
just afraid I may have caused more problems by doing this.
I ordered a new carb & will pick up some new plugs to rule that out
hopefully tomorrow. My timing light is just a basic light with no
dials & I don't have access to anything else unfortunately. It's very
hard to see the mark on the balancer after I get about 25 degrees
advance with my current light. I think I may take a stab at looking
to the timing chain too if the new carb & plugs don't make a
difference unless you guys definitely do not think it's the chain. If
the answer to my previous question about the distributor & oil pump
drive gears is yes, how would I go about putting it back in
correctly? I assume I put the engine at TDC on the compression stroke
for cylinder 1, then make sure the cam & crank sprocket indicators
line up vertically, but is there any specific way the distributor will
need to go in relative to the oil pump drive gear or the cam shaft?
It seems as if there should be some kind of line or marking on the
distributor telling you which way it needs to be dropped in if that's
the case.
Thanks again for everyones help, it's greatly appreciated.
-Matt
07-16-2007, 08:13 PM
#64
Guest
Posts: n/a
Re: CJ5 misfires at high RPM/hard acceleration
I have another question if anyone is familiar with AMC engines. If
the distributor & oil pump gears were removed at the same time, does
it matter which way they go back in? I assume you can only be 180
degrees off, but the oil pump drive gear has turned relative to where
it was when the distributor was removed, which in turn means that the
distributor's actual drive gear will be in a different spot from when
it was removed (if that makes any sense). Does this matter, or is
irrelevant other than deciding the initial position of the distributor
& cap? I assume that it wont matter, & can just be corrected by
moving the distributor whichever way is required to get the timing
back on track after the distributor is dropped back in, but it was one
more thing that I remember doing after I had my symptoms show up,
which may have been present merely from the bad vacuum advance. I'm
just afraid I may have caused more problems by doing this.
I ordered a new carb & will pick up some new plugs to rule that out
hopefully tomorrow. My timing light is just a basic light with no
dials & I don't have access to anything else unfortunately. It's very
hard to see the mark on the balancer after I get about 25 degrees
advance with my current light. I think I may take a stab at looking
to the timing chain too if the new carb & plugs don't make a
difference unless you guys definitely do not think it's the chain. If
the answer to my previous question about the distributor & oil pump
drive gears is yes, how would I go about putting it back in
correctly? I assume I put the engine at TDC on the compression stroke
for cylinder 1, then make sure the cam & crank sprocket indicators
line up vertically, but is there any specific way the distributor will
need to go in relative to the oil pump drive gear or the cam shaft?
It seems as if there should be some kind of line or marking on the
distributor telling you which way it needs to be dropped in if that's
the case.
Thanks again for everyones help, it's greatly appreciated.
-Matt
the distributor & oil pump gears were removed at the same time, does
it matter which way they go back in? I assume you can only be 180
degrees off, but the oil pump drive gear has turned relative to where
it was when the distributor was removed, which in turn means that the
distributor's actual drive gear will be in a different spot from when
it was removed (if that makes any sense). Does this matter, or is
irrelevant other than deciding the initial position of the distributor
& cap? I assume that it wont matter, & can just be corrected by
moving the distributor whichever way is required to get the timing
back on track after the distributor is dropped back in, but it was one
more thing that I remember doing after I had my symptoms show up,
which may have been present merely from the bad vacuum advance. I'm
just afraid I may have caused more problems by doing this.
I ordered a new carb & will pick up some new plugs to rule that out
hopefully tomorrow. My timing light is just a basic light with no
dials & I don't have access to anything else unfortunately. It's very
hard to see the mark on the balancer after I get about 25 degrees
advance with my current light. I think I may take a stab at looking
to the timing chain too if the new carb & plugs don't make a
difference unless you guys definitely do not think it's the chain. If
the answer to my previous question about the distributor & oil pump
drive gears is yes, how would I go about putting it back in
correctly? I assume I put the engine at TDC on the compression stroke
for cylinder 1, then make sure the cam & crank sprocket indicators
line up vertically, but is there any specific way the distributor will
need to go in relative to the oil pump drive gear or the cam shaft?
It seems as if there should be some kind of line or marking on the
distributor telling you which way it needs to be dropped in if that's
the case.
Thanks again for everyones help, it's greatly appreciated.
-Matt
07-16-2007, 08:13 PM
#65
Guest
Posts: n/a
Re: CJ5 misfires at high RPM/hard acceleration
I have another question if anyone is familiar with AMC engines. If
the distributor & oil pump gears were removed at the same time, does
it matter which way they go back in? I assume you can only be 180
degrees off, but the oil pump drive gear has turned relative to where
it was when the distributor was removed, which in turn means that the
distributor's actual drive gear will be in a different spot from when
it was removed (if that makes any sense). Does this matter, or is
irrelevant other than deciding the initial position of the distributor
& cap? I assume that it wont matter, & can just be corrected by
moving the distributor whichever way is required to get the timing
back on track after the distributor is dropped back in, but it was one
more thing that I remember doing after I had my symptoms show up,
which may have been present merely from the bad vacuum advance. I'm
just afraid I may have caused more problems by doing this.
I ordered a new carb & will pick up some new plugs to rule that out
hopefully tomorrow. My timing light is just a basic light with no
dials & I don't have access to anything else unfortunately. It's very
hard to see the mark on the balancer after I get about 25 degrees
advance with my current light. I think I may take a stab at looking
to the timing chain too if the new carb & plugs don't make a
difference unless you guys definitely do not think it's the chain. If
the answer to my previous question about the distributor & oil pump
drive gears is yes, how would I go about putting it back in
correctly? I assume I put the engine at TDC on the compression stroke
for cylinder 1, then make sure the cam & crank sprocket indicators
line up vertically, but is there any specific way the distributor will
need to go in relative to the oil pump drive gear or the cam shaft?
It seems as if there should be some kind of line or marking on the
distributor telling you which way it needs to be dropped in if that's
the case.
Thanks again for everyones help, it's greatly appreciated.
-Matt
the distributor & oil pump gears were removed at the same time, does
it matter which way they go back in? I assume you can only be 180
degrees off, but the oil pump drive gear has turned relative to where
it was when the distributor was removed, which in turn means that the
distributor's actual drive gear will be in a different spot from when
it was removed (if that makes any sense). Does this matter, or is
irrelevant other than deciding the initial position of the distributor
& cap? I assume that it wont matter, & can just be corrected by
moving the distributor whichever way is required to get the timing
back on track after the distributor is dropped back in, but it was one
more thing that I remember doing after I had my symptoms show up,
which may have been present merely from the bad vacuum advance. I'm
just afraid I may have caused more problems by doing this.
I ordered a new carb & will pick up some new plugs to rule that out
hopefully tomorrow. My timing light is just a basic light with no
dials & I don't have access to anything else unfortunately. It's very
hard to see the mark on the balancer after I get about 25 degrees
advance with my current light. I think I may take a stab at looking
to the timing chain too if the new carb & plugs don't make a
difference unless you guys definitely do not think it's the chain. If
the answer to my previous question about the distributor & oil pump
drive gears is yes, how would I go about putting it back in
correctly? I assume I put the engine at TDC on the compression stroke
for cylinder 1, then make sure the cam & crank sprocket indicators
line up vertically, but is there any specific way the distributor will
need to go in relative to the oil pump drive gear or the cam shaft?
It seems as if there should be some kind of line or marking on the
distributor telling you which way it needs to be dropped in if that's
the case.
Thanks again for everyones help, it's greatly appreciated.
-Matt
07-16-2007, 08:51 PM
#66
Guest
Posts: n/a
Re: CJ5 misfires at high RPM/hard acceleration
As I said I don't have any experience on Holley carburators or CJ5s.
I have woked on Webers and Solexes, carbs with no separate throttle base,
and with ported vacum for the advance.
Anyway, if he has a manifold vacuum and not ported vacum signal for the
advance, then the centrifugal advance mechanism plays a more significant
role and will cause more noticeable problems (similar to the ones the OP
has) if it doesn't work.
In the case of manifold vacum signal the distrubutor is timed with less
static advance (the advance measured @idle with vacum disconected), so that
the advance is at acceptable limits when the engine idles were it has full
vacum advance.
When the engine revs above 2800-3000 rpm, it needs about 28 degrees of
advance at full throttle, provided by the centrifugal advance mechanism. If
this is not working, and because there is no vacum advance due to high load
(weak manifold vacum), ending-up with a total advance close to zero degrees,
as much as the static advance causing incomplete combustion, loss of power
and backfiring.
The simple test for the centrifugal advance mechanism is twisting the rotor
and expect it to spring back, but a timing light with the vacuum advance
disconected will show for sure if the centrifugal advance is working.
About the idle speed setting using the butterfly, there are two cases:
1) Carb with only a mixture adjusting screw, where you fine-tune the idle
speed by adjusting the butterfly opening, after having set the mixture screw
to the point that the idle speed is at its highest, just before it begins to
drop.
2) Carb with mixture and bypass screws, where the butterfly must be
completelly closed and idle speed adjusted with the bypass screw, after the
mixture screw is set correctly.
Bill spiliotopoulos,
'96 XJ, '06 TJ.
? "Mike Romain" <romainm@sympatico.ca> ?????? ??? ??????
news:469b8f02$0$22092$9a6e19ea@unlimited.newshosti ng.com...
> Bill Spiliotopoulos wrote:
>> Without having experience on your engine / carb /distributor, I can tell
>> you what is usually the case.
>
> A couple comments...
>
> You are confusing a throttle body and a carburetor with your directions on
> closing the butterfly. Carbs adjust that for idle speed once the mix is
> set, TB's don't.
>
> His engine could be set for 'either' a ported vacuum (vacuum only at
> throttle) or a manifold vacuum. (vacuum highest at idle)
>
> Mine came stock with manifold vacuum, I have switched to ported after some
> modifications.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
I have woked on Webers and Solexes, carbs with no separate throttle base,
and with ported vacum for the advance.
Anyway, if he has a manifold vacuum and not ported vacum signal for the
advance, then the centrifugal advance mechanism plays a more significant
role and will cause more noticeable problems (similar to the ones the OP
has) if it doesn't work.
In the case of manifold vacum signal the distrubutor is timed with less
static advance (the advance measured @idle with vacum disconected), so that
the advance is at acceptable limits when the engine idles were it has full
vacum advance.
When the engine revs above 2800-3000 rpm, it needs about 28 degrees of
advance at full throttle, provided by the centrifugal advance mechanism. If
this is not working, and because there is no vacum advance due to high load
(weak manifold vacum), ending-up with a total advance close to zero degrees,
as much as the static advance causing incomplete combustion, loss of power
and backfiring.
The simple test for the centrifugal advance mechanism is twisting the rotor
and expect it to spring back, but a timing light with the vacuum advance
disconected will show for sure if the centrifugal advance is working.
About the idle speed setting using the butterfly, there are two cases:
1) Carb with only a mixture adjusting screw, where you fine-tune the idle
speed by adjusting the butterfly opening, after having set the mixture screw
to the point that the idle speed is at its highest, just before it begins to
drop.
2) Carb with mixture and bypass screws, where the butterfly must be
completelly closed and idle speed adjusted with the bypass screw, after the
mixture screw is set correctly.
Bill spiliotopoulos,
'96 XJ, '06 TJ.
? "Mike Romain" <romainm@sympatico.ca> ?????? ??? ??????
news:469b8f02$0$22092$9a6e19ea@unlimited.newshosti ng.com...
> Bill Spiliotopoulos wrote:
>> Without having experience on your engine / carb /distributor, I can tell
>> you what is usually the case.
>
> A couple comments...
>
> You are confusing a throttle body and a carburetor with your directions on
> closing the butterfly. Carbs adjust that for idle speed once the mix is
> set, TB's don't.
>
> His engine could be set for 'either' a ported vacuum (vacuum only at
> throttle) or a manifold vacuum. (vacuum highest at idle)
>
> Mine came stock with manifold vacuum, I have switched to ported after some
> modifications.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
07-16-2007, 08:51 PM
#67
Guest
Posts: n/a
Re: CJ5 misfires at high RPM/hard acceleration
As I said I don't have any experience on Holley carburators or CJ5s.
I have woked on Webers and Solexes, carbs with no separate throttle base,
and with ported vacum for the advance.
Anyway, if he has a manifold vacuum and not ported vacum signal for the
advance, then the centrifugal advance mechanism plays a more significant
role and will cause more noticeable problems (similar to the ones the OP
has) if it doesn't work.
In the case of manifold vacum signal the distrubutor is timed with less
static advance (the advance measured @idle with vacum disconected), so that
the advance is at acceptable limits when the engine idles were it has full
vacum advance.
When the engine revs above 2800-3000 rpm, it needs about 28 degrees of
advance at full throttle, provided by the centrifugal advance mechanism. If
this is not working, and because there is no vacum advance due to high load
(weak manifold vacum), ending-up with a total advance close to zero degrees,
as much as the static advance causing incomplete combustion, loss of power
and backfiring.
The simple test for the centrifugal advance mechanism is twisting the rotor
and expect it to spring back, but a timing light with the vacuum advance
disconected will show for sure if the centrifugal advance is working.
About the idle speed setting using the butterfly, there are two cases:
1) Carb with only a mixture adjusting screw, where you fine-tune the idle
speed by adjusting the butterfly opening, after having set the mixture screw
to the point that the idle speed is at its highest, just before it begins to
drop.
2) Carb with mixture and bypass screws, where the butterfly must be
completelly closed and idle speed adjusted with the bypass screw, after the
mixture screw is set correctly.
Bill spiliotopoulos,
'96 XJ, '06 TJ.
? "Mike Romain" <romainm@sympatico.ca> ?????? ??? ??????
news:469b8f02$0$22092$9a6e19ea@unlimited.newshosti ng.com...
> Bill Spiliotopoulos wrote:
>> Without having experience on your engine / carb /distributor, I can tell
>> you what is usually the case.
>
> A couple comments...
>
> You are confusing a throttle body and a carburetor with your directions on
> closing the butterfly. Carbs adjust that for idle speed once the mix is
> set, TB's don't.
>
> His engine could be set for 'either' a ported vacuum (vacuum only at
> throttle) or a manifold vacuum. (vacuum highest at idle)
>
> Mine came stock with manifold vacuum, I have switched to ported after some
> modifications.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
I have woked on Webers and Solexes, carbs with no separate throttle base,
and with ported vacum for the advance.
Anyway, if he has a manifold vacuum and not ported vacum signal for the
advance, then the centrifugal advance mechanism plays a more significant
role and will cause more noticeable problems (similar to the ones the OP
has) if it doesn't work.
In the case of manifold vacum signal the distrubutor is timed with less
static advance (the advance measured @idle with vacum disconected), so that
the advance is at acceptable limits when the engine idles were it has full
vacum advance.
When the engine revs above 2800-3000 rpm, it needs about 28 degrees of
advance at full throttle, provided by the centrifugal advance mechanism. If
this is not working, and because there is no vacum advance due to high load
(weak manifold vacum), ending-up with a total advance close to zero degrees,
as much as the static advance causing incomplete combustion, loss of power
and backfiring.
The simple test for the centrifugal advance mechanism is twisting the rotor
and expect it to spring back, but a timing light with the vacuum advance
disconected will show for sure if the centrifugal advance is working.
About the idle speed setting using the butterfly, there are two cases:
1) Carb with only a mixture adjusting screw, where you fine-tune the idle
speed by adjusting the butterfly opening, after having set the mixture screw
to the point that the idle speed is at its highest, just before it begins to
drop.
2) Carb with mixture and bypass screws, where the butterfly must be
completelly closed and idle speed adjusted with the bypass screw, after the
mixture screw is set correctly.
Bill spiliotopoulos,
'96 XJ, '06 TJ.
? "Mike Romain" <romainm@sympatico.ca> ?????? ??? ??????
news:469b8f02$0$22092$9a6e19ea@unlimited.newshosti ng.com...
> Bill Spiliotopoulos wrote:
>> Without having experience on your engine / carb /distributor, I can tell
>> you what is usually the case.
>
> A couple comments...
>
> You are confusing a throttle body and a carburetor with your directions on
> closing the butterfly. Carbs adjust that for idle speed once the mix is
> set, TB's don't.
>
> His engine could be set for 'either' a ported vacuum (vacuum only at
> throttle) or a manifold vacuum. (vacuum highest at idle)
>
> Mine came stock with manifold vacuum, I have switched to ported after some
> modifications.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
07-16-2007, 08:51 PM
#68
Guest
Posts: n/a
Re: CJ5 misfires at high RPM/hard acceleration
As I said I don't have any experience on Holley carburators or CJ5s.
I have woked on Webers and Solexes, carbs with no separate throttle base,
and with ported vacum for the advance.
Anyway, if he has a manifold vacuum and not ported vacum signal for the
advance, then the centrifugal advance mechanism plays a more significant
role and will cause more noticeable problems (similar to the ones the OP
has) if it doesn't work.
In the case of manifold vacum signal the distrubutor is timed with less
static advance (the advance measured @idle with vacum disconected), so that
the advance is at acceptable limits when the engine idles were it has full
vacum advance.
When the engine revs above 2800-3000 rpm, it needs about 28 degrees of
advance at full throttle, provided by the centrifugal advance mechanism. If
this is not working, and because there is no vacum advance due to high load
(weak manifold vacum), ending-up with a total advance close to zero degrees,
as much as the static advance causing incomplete combustion, loss of power
and backfiring.
The simple test for the centrifugal advance mechanism is twisting the rotor
and expect it to spring back, but a timing light with the vacuum advance
disconected will show for sure if the centrifugal advance is working.
About the idle speed setting using the butterfly, there are two cases:
1) Carb with only a mixture adjusting screw, where you fine-tune the idle
speed by adjusting the butterfly opening, after having set the mixture screw
to the point that the idle speed is at its highest, just before it begins to
drop.
2) Carb with mixture and bypass screws, where the butterfly must be
completelly closed and idle speed adjusted with the bypass screw, after the
mixture screw is set correctly.
Bill spiliotopoulos,
'96 XJ, '06 TJ.
? "Mike Romain" <romainm@sympatico.ca> ?????? ??? ??????
news:469b8f02$0$22092$9a6e19ea@unlimited.newshosti ng.com...
> Bill Spiliotopoulos wrote:
>> Without having experience on your engine / carb /distributor, I can tell
>> you what is usually the case.
>
> A couple comments...
>
> You are confusing a throttle body and a carburetor with your directions on
> closing the butterfly. Carbs adjust that for idle speed once the mix is
> set, TB's don't.
>
> His engine could be set for 'either' a ported vacuum (vacuum only at
> throttle) or a manifold vacuum. (vacuum highest at idle)
>
> Mine came stock with manifold vacuum, I have switched to ported after some
> modifications.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
I have woked on Webers and Solexes, carbs with no separate throttle base,
and with ported vacum for the advance.
Anyway, if he has a manifold vacuum and not ported vacum signal for the
advance, then the centrifugal advance mechanism plays a more significant
role and will cause more noticeable problems (similar to the ones the OP
has) if it doesn't work.
In the case of manifold vacum signal the distrubutor is timed with less
static advance (the advance measured @idle with vacum disconected), so that
the advance is at acceptable limits when the engine idles were it has full
vacum advance.
When the engine revs above 2800-3000 rpm, it needs about 28 degrees of
advance at full throttle, provided by the centrifugal advance mechanism. If
this is not working, and because there is no vacum advance due to high load
(weak manifold vacum), ending-up with a total advance close to zero degrees,
as much as the static advance causing incomplete combustion, loss of power
and backfiring.
The simple test for the centrifugal advance mechanism is twisting the rotor
and expect it to spring back, but a timing light with the vacuum advance
disconected will show for sure if the centrifugal advance is working.
About the idle speed setting using the butterfly, there are two cases:
1) Carb with only a mixture adjusting screw, where you fine-tune the idle
speed by adjusting the butterfly opening, after having set the mixture screw
to the point that the idle speed is at its highest, just before it begins to
drop.
2) Carb with mixture and bypass screws, where the butterfly must be
completelly closed and idle speed adjusted with the bypass screw, after the
mixture screw is set correctly.
Bill spiliotopoulos,
'96 XJ, '06 TJ.
? "Mike Romain" <romainm@sympatico.ca> ?????? ??? ??????
news:469b8f02$0$22092$9a6e19ea@unlimited.newshosti ng.com...
> Bill Spiliotopoulos wrote:
>> Without having experience on your engine / carb /distributor, I can tell
>> you what is usually the case.
>
> A couple comments...
>
> You are confusing a throttle body and a carburetor with your directions on
> closing the butterfly. Carbs adjust that for idle speed once the mix is
> set, TB's don't.
>
> His engine could be set for 'either' a ported vacuum (vacuum only at
> throttle) or a manifold vacuum. (vacuum highest at idle)
>
> Mine came stock with manifold vacuum, I have switched to ported after some
> modifications.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
07-16-2007, 08:51 PM
#69
Guest
Posts: n/a
Re: CJ5 misfires at high RPM/hard acceleration
As I said I don't have any experience on Holley carburators or CJ5s.
I have woked on Webers and Solexes, carbs with no separate throttle base,
and with ported vacum for the advance.
Anyway, if he has a manifold vacuum and not ported vacum signal for the
advance, then the centrifugal advance mechanism plays a more significant
role and will cause more noticeable problems (similar to the ones the OP
has) if it doesn't work.
In the case of manifold vacum signal the distrubutor is timed with less
static advance (the advance measured @idle with vacum disconected), so that
the advance is at acceptable limits when the engine idles were it has full
vacum advance.
When the engine revs above 2800-3000 rpm, it needs about 28 degrees of
advance at full throttle, provided by the centrifugal advance mechanism. If
this is not working, and because there is no vacum advance due to high load
(weak manifold vacum), ending-up with a total advance close to zero degrees,
as much as the static advance causing incomplete combustion, loss of power
and backfiring.
The simple test for the centrifugal advance mechanism is twisting the rotor
and expect it to spring back, but a timing light with the vacuum advance
disconected will show for sure if the centrifugal advance is working.
About the idle speed setting using the butterfly, there are two cases:
1) Carb with only a mixture adjusting screw, where you fine-tune the idle
speed by adjusting the butterfly opening, after having set the mixture screw
to the point that the idle speed is at its highest, just before it begins to
drop.
2) Carb with mixture and bypass screws, where the butterfly must be
completelly closed and idle speed adjusted with the bypass screw, after the
mixture screw is set correctly.
Bill spiliotopoulos,
'96 XJ, '06 TJ.
? "Mike Romain" <romainm@sympatico.ca> ?????? ??? ??????
news:469b8f02$0$22092$9a6e19ea@unlimited.newshosti ng.com...
> Bill Spiliotopoulos wrote:
>> Without having experience on your engine / carb /distributor, I can tell
>> you what is usually the case.
>
> A couple comments...
>
> You are confusing a throttle body and a carburetor with your directions on
> closing the butterfly. Carbs adjust that for idle speed once the mix is
> set, TB's don't.
>
> His engine could be set for 'either' a ported vacuum (vacuum only at
> throttle) or a manifold vacuum. (vacuum highest at idle)
>
> Mine came stock with manifold vacuum, I have switched to ported after some
> modifications.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
I have woked on Webers and Solexes, carbs with no separate throttle base,
and with ported vacum for the advance.
Anyway, if he has a manifold vacuum and not ported vacum signal for the
advance, then the centrifugal advance mechanism plays a more significant
role and will cause more noticeable problems (similar to the ones the OP
has) if it doesn't work.
In the case of manifold vacum signal the distrubutor is timed with less
static advance (the advance measured @idle with vacum disconected), so that
the advance is at acceptable limits when the engine idles were it has full
vacum advance.
When the engine revs above 2800-3000 rpm, it needs about 28 degrees of
advance at full throttle, provided by the centrifugal advance mechanism. If
this is not working, and because there is no vacum advance due to high load
(weak manifold vacum), ending-up with a total advance close to zero degrees,
as much as the static advance causing incomplete combustion, loss of power
and backfiring.
The simple test for the centrifugal advance mechanism is twisting the rotor
and expect it to spring back, but a timing light with the vacuum advance
disconected will show for sure if the centrifugal advance is working.
About the idle speed setting using the butterfly, there are two cases:
1) Carb with only a mixture adjusting screw, where you fine-tune the idle
speed by adjusting the butterfly opening, after having set the mixture screw
to the point that the idle speed is at its highest, just before it begins to
drop.
2) Carb with mixture and bypass screws, where the butterfly must be
completelly closed and idle speed adjusted with the bypass screw, after the
mixture screw is set correctly.
Bill spiliotopoulos,
'96 XJ, '06 TJ.
? "Mike Romain" <romainm@sympatico.ca> ?????? ??? ??????
news:469b8f02$0$22092$9a6e19ea@unlimited.newshosti ng.com...
> Bill Spiliotopoulos wrote:
>> Without having experience on your engine / carb /distributor, I can tell
>> you what is usually the case.
>
> A couple comments...
>
> You are confusing a throttle body and a carburetor with your directions on
> closing the butterfly. Carbs adjust that for idle speed once the mix is
> set, TB's don't.
>
> His engine could be set for 'either' a ported vacuum (vacuum only at
> throttle) or a manifold vacuum. (vacuum highest at idle)
>
> Mine came stock with manifold vacuum, I have switched to ported after some
> modifications.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
07-17-2007, 05:46 AM
#70
Guest
Posts: n/a
Re: CJ5 misfires at high RPM/hard acceleration
On Mon, 16 Jul 2007 15:41:05 -0400, Mike Romain <romainm@sympatico.ca>
wrote:
>SnoMan wrote:
>> On Mon, 16 Jul 2007 10:15:36 -0400, Mike Romain <romainm@sympatico.ca>
>> wrote:
>>
>>> 'All' the old Jeep engines 'I' personally have seen (and read about
>>> 'many') will 'NOT' run on Bosch platinum plugs.
>>>
>>> They foul up almost immediately.
>>>
>>> I would change those before doing anything else and put proper Champion
>>> truck plugs back into it.
>>
>> Where do you get this BS at?????
>
>'I' actually have worked on Jeep engines and 'fixed' a whole bunch with
>fouling Bosch plugs.
>
>Lots of folks get suckered by the hype and change out the Champion plugs.
>
>If you Google this group, you will find the the older Jeep engines will
>'not' run on Bosch plugs, period.
>
>It is well documented and a very common cause of fouling plugs.
>
>It is also a very common topic on other groups that deal with American
>engines.
>
>Bosch might have the heat ranges totally screwed in their book for Jeep
>engines, who knows, but they don't work.
Gotta agree with you here, Mike. I've fixed many a misfire by
ditching the Bosch plugs. Not just in Jeeps, either, my '61 F-100
didn't like them, and neither did my bud's Harley.
--
Old Crow "Yol Bolsun!"
'82 FLTC-P "Miss Pearl"
'95 YJ Rio Grande
BS#133, SENS, TOMKAT, MAMBM
--
Posted via a free Usenet account from http://www.teranews.com
wrote:
>SnoMan wrote:
>> On Mon, 16 Jul 2007 10:15:36 -0400, Mike Romain <romainm@sympatico.ca>
>> wrote:
>>
>>> 'All' the old Jeep engines 'I' personally have seen (and read about
>>> 'many') will 'NOT' run on Bosch platinum plugs.
>>>
>>> They foul up almost immediately.
>>>
>>> I would change those before doing anything else and put proper Champion
>>> truck plugs back into it.
>>
>> Where do you get this BS at?????
>
>'I' actually have worked on Jeep engines and 'fixed' a whole bunch with
>fouling Bosch plugs.
>
>Lots of folks get suckered by the hype and change out the Champion plugs.
>
>If you Google this group, you will find the the older Jeep engines will
>'not' run on Bosch plugs, period.
>
>It is well documented and a very common cause of fouling plugs.
>
>It is also a very common topic on other groups that deal with American
>engines.
>
>Bosch might have the heat ranges totally screwed in their book for Jeep
>engines, who knows, but they don't work.
Gotta agree with you here, Mike. I've fixed many a misfire by
ditching the Bosch plugs. Not just in Jeeps, either, my '61 F-100
didn't like them, and neither did my bud's Harley.
--
Old Crow "Yol Bolsun!"
'82 FLTC-P "Miss Pearl"
'95 YJ Rio Grande
BS#133, SENS, TOMKAT, MAMBM
--
Posted via a free Usenet account from http://www.teranews.com