Rich Hampel

I can put in a less strong spring under the power piston in the carb;
but, I'll still be operating the brake booster with insufficient
vacuum.

It all comes back to (and no matter what the 'numbers' on the vac gage
are) is that this engine just isnt getting proper vacuum in the intake
manifold and Im stumped on how to increase the vacuum.

Its not the carb as I have set up the carb on a stationary engine
pulling proper vacuum .... and when I move it to the Jeepster it runs
like SH*T because of the low vacuum. Yeah I can re-jet and fiddle with
different thickness metering rods .... but the real problem is LOW
manifold vacuum !!!!!

Ive never been quite so 'stumped' like this before ... therefore the
posting for HELP!

:-)



In article <41ED9A0B.6162BEF9@***.net>, ßill <----------@***.net> wrote:

> Then I would calibrate it, get the wife's fingernail polish out and
> make a mark on your gauge and call it eighteen.
> God Bless America, ßill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Rich Hampel wrote:
> >
> > I've isolated EVERY exterior control and vacuum body including the
> > brake booster and am pretty much convinced that its an 'engine'
> > problem.
> >
> > Im using an uncalibrated vac. gauge.... the the real symptoms are still
> > the low brake booster output, the inability to pull down the power
> > piston in the carb, etc....

Rich Hampel

I can put in a less strong spring under the power piston in the carb;
but, I'll still be operating the brake booster with insufficient
vacuum.

It all comes back to (and no matter what the 'numbers' on the vac gage
are) is that this engine just isnt getting proper vacuum in the intake
manifold and Im stumped on how to increase the vacuum.

Its not the carb as I have set up the carb on a stationary engine
pulling proper vacuum .... and when I move it to the Jeepster it runs
like SH*T because of the low vacuum. Yeah I can re-jet and fiddle with
different thickness metering rods .... but the real problem is LOW
manifold vacuum !!!!!

Ive never been quite so 'stumped' like this before ... therefore the
posting for HELP!

:-)



In article <41ED9A0B.6162BEF9@***.net>, ßill <----------@***.net> wrote:

> Then I would calibrate it, get the wife's fingernail polish out and
> make a mark on your gauge and call it eighteen.
> God Bless America, ßill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Rich Hampel wrote:
> >
> > I've isolated EVERY exterior control and vacuum body including the
> > brake booster and am pretty much convinced that its an 'engine'
> > problem.
> >
> > Im using an uncalibrated vac. gauge.... the the real symptoms are still
> > the low brake booster output, the inability to pull down the power
> > piston in the carb, etc....

SteveBrady

haha...you beat me to it Bill!

We use compressors at work and were chasing a leak for a week (I can rhyme,
what a time!). In the end it turned out the leak was in the regulator
guage. Didn't soap there! Ah well!



"L.W. ("ßill") ------ III" <----------@***.net> wrote in message
news:41ED9A0B.6162BEF9@***.net...
> Then I would calibrate it, get the wife's fingernail polish out and
> make a mark on your gauge and call it eighteen.
> God Bless America, ßill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Rich Hampel wrote:
>>
>> I've isolated EVERY exterior control and vacuum body including the
>> brake booster and am pretty much convinced that its an 'engine'
>> problem.
>>
>> Im using an uncalibrated vac. gauge.... the the real symptoms are still
>> the low brake booster output, the inability to pull down the power
>> piston in the carb, etc....

SteveBrady

haha...you beat me to it Bill!

We use compressors at work and were chasing a leak for a week (I can rhyme,
what a time!). In the end it turned out the leak was in the regulator
guage. Didn't soap there! Ah well!



"L.W. ("ßill") ------ III" <----------@***.net> wrote in message
news:41ED9A0B.6162BEF9@***.net...
> Then I would calibrate it, get the wife's fingernail polish out and
> make a mark on your gauge and call it eighteen.
> God Bless America, ßill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Rich Hampel wrote:
>>
>> I've isolated EVERY exterior control and vacuum body including the
>> brake booster and am pretty much convinced that its an 'engine'
>> problem.
>>
>> Im using an uncalibrated vac. gauge.... the the real symptoms are still
>> the low brake booster output, the inability to pull down the power
>> piston in the carb, etc....

SteveBrady

haha...you beat me to it Bill!

We use compressors at work and were chasing a leak for a week (I can rhyme,
what a time!). In the end it turned out the leak was in the regulator
guage. Didn't soap there! Ah well!



"L.W. ("ßill") ------ III" <----------@***.net> wrote in message
news:41ED9A0B.6162BEF9@***.net...
> Then I would calibrate it, get the wife's fingernail polish out and
> make a mark on your gauge and call it eighteen.
> God Bless America, ßill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Rich Hampel wrote:
>>
>> I've isolated EVERY exterior control and vacuum body including the
>> brake booster and am pretty much convinced that its an 'engine'
>> problem.
>>
>> Im using an uncalibrated vac. gauge.... the the real symptoms are still
>> the low brake booster output, the inability to pull down the power
>> piston in the carb, etc....

c

"DougW" <post.replies@invalid.address> wrote in message
news:82jHd.11113$sF5.3191@okepread06...
> Rich Hampel did pass the time by typing:
> > I can put in a less strong spring under the power piston in the carb;
> > but, I'll still be operating the brake booster with insufficient
> > vacuum.
> >
> > It all comes back to (and no matter what the 'numbers' on the vac gage
> > are) is that this engine just isnt getting proper vacuum in the intake
> > manifold and Im stumped on how to increase the vacuum.
> >
> > Its not the carb as I have set up the carb on a stationary engine
> > pulling proper vacuum .... and when I move it to the Jeepster it runs
> > like SH*T because of the low vacuum. Yeah I can re-jet and fiddle with
> > different thickness metering rods .... but the real problem is LOW
> > manifold vacuum !!!!!
> >
> > Ive never been quite so 'stumped' like this before ... therefore the
> > posting for HELP!
>
> What's your vac gauge needle doing? If it's fluctuating then it could
> be valves, if it's fairly constant than you might have an intake leak
> and should spray a bit of carb cleaner around to find it.
>
> Other ideas. EGR valve stuck? Bad match on the carb base, gasket, and
> intake? Doesn't have to be on the outside to cause a problem.
>
> Just random thinkin.
>
> Good luck
>
> --
> DougW
>
>

All good ideas. Also, it is wise to look for exhaust restrictions,
especially the convertor. This will cause lower vacuum as well. One other
thing that I didn't see if it was posted, is the camshaft stock or
aftermarket? An aftermarket cam with more duration will cause lower vacuum
as well.

Chris

c

"DougW" <post.replies@invalid.address> wrote in message
news:82jHd.11113$sF5.3191@okepread06...
> Rich Hampel did pass the time by typing:
> > I can put in a less strong spring under the power piston in the carb;
> > but, I'll still be operating the brake booster with insufficient
> > vacuum.
> >
> > It all comes back to (and no matter what the 'numbers' on the vac gage
> > are) is that this engine just isnt getting proper vacuum in the intake
> > manifold and Im stumped on how to increase the vacuum.
> >
> > Its not the carb as I have set up the carb on a stationary engine
> > pulling proper vacuum .... and when I move it to the Jeepster it runs
> > like SH*T because of the low vacuum. Yeah I can re-jet and fiddle with
> > different thickness metering rods .... but the real problem is LOW
> > manifold vacuum !!!!!
> >
> > Ive never been quite so 'stumped' like this before ... therefore the
> > posting for HELP!
>
> What's your vac gauge needle doing? If it's fluctuating then it could
> be valves, if it's fairly constant than you might have an intake leak
> and should spray a bit of carb cleaner around to find it.
>
> Other ideas. EGR valve stuck? Bad match on the carb base, gasket, and
> intake? Doesn't have to be on the outside to cause a problem.
>
> Just random thinkin.
>
> Good luck
>
> --
> DougW
>
>

All good ideas. Also, it is wise to look for exhaust restrictions,
especially the convertor. This will cause lower vacuum as well. One other
thing that I didn't see if it was posted, is the camshaft stock or
aftermarket? An aftermarket cam with more duration will cause lower vacuum
as well.

Chris

c

"DougW" <post.replies@invalid.address> wrote in message
news:82jHd.11113$sF5.3191@okepread06...
> Rich Hampel did pass the time by typing:
> > I can put in a less strong spring under the power piston in the carb;
> > but, I'll still be operating the brake booster with insufficient
> > vacuum.
> >
> > It all comes back to (and no matter what the 'numbers' on the vac gage
> > are) is that this engine just isnt getting proper vacuum in the intake
> > manifold and Im stumped on how to increase the vacuum.
> >
> > Its not the carb as I have set up the carb on a stationary engine
> > pulling proper vacuum .... and when I move it to the Jeepster it runs
> > like SH*T because of the low vacuum. Yeah I can re-jet and fiddle with
> > different thickness metering rods .... but the real problem is LOW
> > manifold vacuum !!!!!
> >
> > Ive never been quite so 'stumped' like this before ... therefore the
> > posting for HELP!
>
> What's your vac gauge needle doing? If it's fluctuating then it could
> be valves, if it's fairly constant than you might have an intake leak
> and should spray a bit of carb cleaner around to find it.
>
> Other ideas. EGR valve stuck? Bad match on the carb base, gasket, and
> intake? Doesn't have to be on the outside to cause a problem.
>
> Just random thinkin.
>
> Good luck
>
> --
> DougW
>
>

All good ideas. Also, it is wise to look for exhaust restrictions,
especially the convertor. This will cause lower vacuum as well. One other
thing that I didn't see if it was posted, is the camshaft stock or
aftermarket? An aftermarket cam with more duration will cause lower vacuum
as well.

Chris

Jeff Strickland

You know, my instinct says that you might have a problem with one or more of
the vac loads. We have heard of vac boosters on the power brakes failing and
letting the vac pressure drop. I have to wonder if you are suffering for
something along this line.

I am not sure, but I think the test for this is to unplug all vac loads in
the system, and block them off. See what the vac is, then plug each in one
at a time and see where the vac drops.






"Rich Hampel" <RhmpL33@nospam.net> wrote in message
news:180120051536111216%RhmpL33@nospam.net...
> "problem" performance continues in a rebuilt 2.8L GM .....
> Engine now has 4000 miles on it and still has relatively low manifold
> vacuum. Vacuum is running 14-15 in hg. at idle and should be a few
> inches MORE vac. to adequately run all the vacuum controls: Brake
> booster, heater controls, dist. vacuum advance, *power piston* (2SE
> carb), etc.
>
> I checked and checked for manifold leaks, reset the damn manifold
> gaskets three times.... etc.
> Im pretty damn sure the problem is the engine 'mechanicals' .
> Compression is 130 psig all cylinders
> Mechanical valve timing has been degreed, and verified OK.
> Ignition timing perfect - both by vacuum gauge (max rpm less 1/2" hg.)
> and by accurate degreeing + timing light. --- both methods equate to
> the same EXACT timing advance.
> NO leaking vacuum hoses or controls.
> If I remove a vac. hose from the manifold port the engine
> **increases*** rpm --- which tells me I dont have a leak.
> Poor vacuum causes power piston in carb to lift 'early' (for over-rich
> mixture) - if I manually hold power piston / metering rod and remove a
> manifold vac hose = same rpm increase.
>
> Engine was broken in with 20 weight straight weight non-detergent oil.
>
> Im about ready to dump a half can of cleanser down the carb to scuff
> the cylinder walls in desparation and run the valve lifters with ZERO
> lash ......
>
> Your sage advice would be appreciated. I need another 2-3 inches of
> vacuum to make all the vac. controls, brake booster and power piston-ed
> carb. to operate properly. Any advice of why this damn engine is
> running 'short' by about 2-3 inches hg. of vacuum and what to do about
> it would be VEEEEEEEERRRRRRRRRRYYYYYYYYY much appreciated.
>
> ;-)

Jeff Strickland

You know, my instinct says that you might have a problem with one or more of
the vac loads. We have heard of vac boosters on the power brakes failing and
letting the vac pressure drop. I have to wonder if you are suffering for
something along this line.

I am not sure, but I think the test for this is to unplug all vac loads in
the system, and block them off. See what the vac is, then plug each in one
at a time and see where the vac drops.






"Rich Hampel" <RhmpL33@nospam.net> wrote in message
news:180120051536111216%RhmpL33@nospam.net...
> "problem" performance continues in a rebuilt 2.8L GM .....
> Engine now has 4000 miles on it and still has relatively low manifold
> vacuum. Vacuum is running 14-15 in hg. at idle and should be a few
> inches MORE vac. to adequately run all the vacuum controls: Brake
> booster, heater controls, dist. vacuum advance, *power piston* (2SE
> carb), etc.
>
> I checked and checked for manifold leaks, reset the damn manifold
> gaskets three times.... etc.
> Im pretty damn sure the problem is the engine 'mechanicals' .
> Compression is 130 psig all cylinders
> Mechanical valve timing has been degreed, and verified OK.
> Ignition timing perfect - both by vacuum gauge (max rpm less 1/2" hg.)
> and by accurate degreeing + timing light. --- both methods equate to
> the same EXACT timing advance.
> NO leaking vacuum hoses or controls.
> If I remove a vac. hose from the manifold port the engine
> **increases*** rpm --- which tells me I dont have a leak.
> Poor vacuum causes power piston in carb to lift 'early' (for over-rich
> mixture) - if I manually hold power piston / metering rod and remove a
> manifold vac hose = same rpm increase.
>
> Engine was broken in with 20 weight straight weight non-detergent oil.
>
> Im about ready to dump a half can of cleanser down the carb to scuff
> the cylinder walls in desparation and run the valve lifters with ZERO
> lash ......
>
> Your sage advice would be appreciated. I need another 2-3 inches of
> vacuum to make all the vac. controls, brake booster and power piston-ed
> carb. to operate properly. Any advice of why this damn engine is
> running 'short' by about 2-3 inches hg. of vacuum and what to do about
> it would be VEEEEEEEERRRRRRRRRRYYYYYYYYY much appreciated.
>
> ;-)