Low Manifold Vacuum
#11
Guest
Posts: n/a
Re: Low Manifold Vacuum
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....
In article <52fHd.13285$GG1.4158@text.news.blueyonder.co.uk >, Dave
Milne <jeep@_nospam_milne.info> wrote:
> 1st up, I'm not familiar with the 2.8, but is it possible you have a leak in
> your brake servo ? You say the problem continues in a new engine ?
>
> Dave Milne, Scotland
> '91 Grand Wagoneer, '99 TJ
>
> "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.
> >
> > ;-)
>
>
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....
In article <52fHd.13285$GG1.4158@text.news.blueyonder.co.uk >, Dave
Milne <jeep@_nospam_milne.info> wrote:
> 1st up, I'm not familiar with the 2.8, but is it possible you have a leak in
> your brake servo ? You say the problem continues in a new engine ?
>
> Dave Milne, Scotland
> '91 Grand Wagoneer, '99 TJ
>
> "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.
> >
> > ;-)
>
>
#12
Guest
Posts: n/a
Re: Low Manifold Vacuum
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....
In article <52fHd.13285$GG1.4158@text.news.blueyonder.co.uk >, Dave
Milne <jeep@_nospam_milne.info> wrote:
> 1st up, I'm not familiar with the 2.8, but is it possible you have a leak in
> your brake servo ? You say the problem continues in a new engine ?
>
> Dave Milne, Scotland
> '91 Grand Wagoneer, '99 TJ
>
> "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.
> >
> > ;-)
>
>
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....
In article <52fHd.13285$GG1.4158@text.news.blueyonder.co.uk >, Dave
Milne <jeep@_nospam_milne.info> wrote:
> 1st up, I'm not familiar with the 2.8, but is it possible you have a leak in
> your brake servo ? You say the problem continues in a new engine ?
>
> Dave Milne, Scotland
> '91 Grand Wagoneer, '99 TJ
>
> "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.
> >
> > ;-)
>
>
#13
Guest
Posts: n/a
Re: Low Manifold Vacuum
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....
In article <52fHd.13285$GG1.4158@text.news.blueyonder.co.uk >, Dave
Milne <jeep@_nospam_milne.info> wrote:
> 1st up, I'm not familiar with the 2.8, but is it possible you have a leak in
> your brake servo ? You say the problem continues in a new engine ?
>
> Dave Milne, Scotland
> '91 Grand Wagoneer, '99 TJ
>
> "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.
> >
> > ;-)
>
>
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....
In article <52fHd.13285$GG1.4158@text.news.blueyonder.co.uk >, Dave
Milne <jeep@_nospam_milne.info> wrote:
> 1st up, I'm not familiar with the 2.8, but is it possible you have a leak in
> your brake servo ? You say the problem continues in a new engine ?
>
> Dave Milne, Scotland
> '91 Grand Wagoneer, '99 TJ
>
> "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.
> >
> > ;-)
>
>
#14
Guest
Posts: n/a
Re: Low Manifold Vacuum
At cruise speeds and with the throttle plate essentially closed there
isnt much difference of manifold vacuum than at idle -- just an inch or
two. .... just low vacuum. Ive isolated and locked-out all the vacuum
accessories one by one to prove to myself that these were not the
cause.
In article <41ED7CCF.6F4C4AD6@***.net>, ßill <----------@***.net> wrote:
> That's not really low for a SMOG motor at idle. You may see that's
> at the edge of the green zone: http://www.----------.com/vacuumgauge.jpg
> And you have noticed it's up around twenty at the more efficient
> operating Revolutions Per Minute. None of the accessories use vacuum,
> unless used.
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> Rich Hampel wrote:
> >
> > "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.
> >
> > ;-)
isnt much difference of manifold vacuum than at idle -- just an inch or
two. .... just low vacuum. Ive isolated and locked-out all the vacuum
accessories one by one to prove to myself that these were not the
cause.
In article <41ED7CCF.6F4C4AD6@***.net>, ßill <----------@***.net> wrote:
> That's not really low for a SMOG motor at idle. You may see that's
> at the edge of the green zone: http://www.----------.com/vacuumgauge.jpg
> And you have noticed it's up around twenty at the more efficient
> operating Revolutions Per Minute. None of the accessories use vacuum,
> unless used.
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> Rich Hampel wrote:
> >
> > "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.
> >
> > ;-)
#15
Guest
Posts: n/a
Re: Low Manifold Vacuum
At cruise speeds and with the throttle plate essentially closed there
isnt much difference of manifold vacuum than at idle -- just an inch or
two. .... just low vacuum. Ive isolated and locked-out all the vacuum
accessories one by one to prove to myself that these were not the
cause.
In article <41ED7CCF.6F4C4AD6@***.net>, ßill <----------@***.net> wrote:
> That's not really low for a SMOG motor at idle. You may see that's
> at the edge of the green zone: http://www.----------.com/vacuumgauge.jpg
> And you have noticed it's up around twenty at the more efficient
> operating Revolutions Per Minute. None of the accessories use vacuum,
> unless used.
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> Rich Hampel wrote:
> >
> > "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.
> >
> > ;-)
isnt much difference of manifold vacuum than at idle -- just an inch or
two. .... just low vacuum. Ive isolated and locked-out all the vacuum
accessories one by one to prove to myself that these were not the
cause.
In article <41ED7CCF.6F4C4AD6@***.net>, ßill <----------@***.net> wrote:
> That's not really low for a SMOG motor at idle. You may see that's
> at the edge of the green zone: http://www.----------.com/vacuumgauge.jpg
> And you have noticed it's up around twenty at the more efficient
> operating Revolutions Per Minute. None of the accessories use vacuum,
> unless used.
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> Rich Hampel wrote:
> >
> > "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.
> >
> > ;-)
#16
Guest
Posts: n/a
Re: Low Manifold Vacuum
At cruise speeds and with the throttle plate essentially closed there
isnt much difference of manifold vacuum than at idle -- just an inch or
two. .... just low vacuum. Ive isolated and locked-out all the vacuum
accessories one by one to prove to myself that these were not the
cause.
In article <41ED7CCF.6F4C4AD6@***.net>, ßill <----------@***.net> wrote:
> That's not really low for a SMOG motor at idle. You may see that's
> at the edge of the green zone: http://www.----------.com/vacuumgauge.jpg
> And you have noticed it's up around twenty at the more efficient
> operating Revolutions Per Minute. None of the accessories use vacuum,
> unless used.
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> Rich Hampel wrote:
> >
> > "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.
> >
> > ;-)
isnt much difference of manifold vacuum than at idle -- just an inch or
two. .... just low vacuum. Ive isolated and locked-out all the vacuum
accessories one by one to prove to myself that these were not the
cause.
In article <41ED7CCF.6F4C4AD6@***.net>, ßill <----------@***.net> wrote:
> That's not really low for a SMOG motor at idle. You may see that's
> at the edge of the green zone: http://www.----------.com/vacuumgauge.jpg
> And you have noticed it's up around twenty at the more efficient
> operating Revolutions Per Minute. None of the accessories use vacuum,
> unless used.
> God Bless America, ßill O|||||||O
> mailto:--------------------
>
> Rich Hampel wrote:
> >
> > "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.
> >
> > ;-)
#17
Guest
Posts: n/a
Re: Low Manifold Vacuum
Yeah... my book has zero lash ... but is defined as frictional contact
on the pushrods, then 3/4 turn on the friction nut.
I dont have the means to do a ''pressurized leak down test' at home ...
so Im just guessing about the valves.
In article <41ED826D.5F3A956A@sympatico.ca>, Mike Romain
<romainm@sympatico.ca> wrote:
> I would guess that your valves are a bit short on time if you don't have
> zero lash on them. My book calls for zero.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Rich Hampel wrote:
> >
> > "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.
> >
> > ;-)
on the pushrods, then 3/4 turn on the friction nut.
I dont have the means to do a ''pressurized leak down test' at home ...
so Im just guessing about the valves.
In article <41ED826D.5F3A956A@sympatico.ca>, Mike Romain
<romainm@sympatico.ca> wrote:
> I would guess that your valves are a bit short on time if you don't have
> zero lash on them. My book calls for zero.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Rich Hampel wrote:
> >
> > "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.
> >
> > ;-)
#18
Guest
Posts: n/a
Re: Low Manifold Vacuum
Yeah... my book has zero lash ... but is defined as frictional contact
on the pushrods, then 3/4 turn on the friction nut.
I dont have the means to do a ''pressurized leak down test' at home ...
so Im just guessing about the valves.
In article <41ED826D.5F3A956A@sympatico.ca>, Mike Romain
<romainm@sympatico.ca> wrote:
> I would guess that your valves are a bit short on time if you don't have
> zero lash on them. My book calls for zero.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Rich Hampel wrote:
> >
> > "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.
> >
> > ;-)
on the pushrods, then 3/4 turn on the friction nut.
I dont have the means to do a ''pressurized leak down test' at home ...
so Im just guessing about the valves.
In article <41ED826D.5F3A956A@sympatico.ca>, Mike Romain
<romainm@sympatico.ca> wrote:
> I would guess that your valves are a bit short on time if you don't have
> zero lash on them. My book calls for zero.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Rich Hampel wrote:
> >
> > "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.
> >
> > ;-)
#19
Guest
Posts: n/a
Re: Low Manifold Vacuum
Yeah... my book has zero lash ... but is defined as frictional contact
on the pushrods, then 3/4 turn on the friction nut.
I dont have the means to do a ''pressurized leak down test' at home ...
so Im just guessing about the valves.
In article <41ED826D.5F3A956A@sympatico.ca>, Mike Romain
<romainm@sympatico.ca> wrote:
> I would guess that your valves are a bit short on time if you don't have
> zero lash on them. My book calls for zero.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Rich Hampel wrote:
> >
> > "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.
> >
> > ;-)
on the pushrods, then 3/4 turn on the friction nut.
I dont have the means to do a ''pressurized leak down test' at home ...
so Im just guessing about the valves.
In article <41ED826D.5F3A956A@sympatico.ca>, Mike Romain
<romainm@sympatico.ca> wrote:
> I would guess that your valves are a bit short on time if you don't have
> zero lash on them. My book calls for zero.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Rich Hampel wrote:
> >
> > "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.
> >
> > ;-)
#20
Guest
Posts: n/a
Re: Low Manifold Vacuum
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....
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....