vacuum question
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Joined: May 2014
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From: Washington nj
vacuum question
Hi all.
I'm hooking up a vacuum pump and reserve tank to make up for my lack of engine vacuum for my brakes in my 74. Can I, should I leave the engine vacuum hooked up in parallel whith the new system, or cap it off? Was thinking of leaving it hooked up in case pump fails. Going this route because when I checked vacuum I only had about 8 Hg. That was with all vacuum lines still tied in. Assuming the low vacuum is from modified engine, a 383. Done before me. Pump is primarily for brakes, but may hook in other vacuum loads, lights, climate control. I'll see how it works first with brakes. Guess I should try and see if I have any leaks in the system for lights, etc first though. Then same question, cap the engine vacuum from that system? Brake vacuum is from carb and lights from manifold.
Thanks Brent
I'm hooking up a vacuum pump and reserve tank to make up for my lack of engine vacuum for my brakes in my 74. Can I, should I leave the engine vacuum hooked up in parallel whith the new system, or cap it off? Was thinking of leaving it hooked up in case pump fails. Going this route because when I checked vacuum I only had about 8 Hg. That was with all vacuum lines still tied in. Assuming the low vacuum is from modified engine, a 383. Done before me. Pump is primarily for brakes, but may hook in other vacuum loads, lights, climate control. I'll see how it works first with brakes. Guess I should try and see if I have any leaks in the system for lights, etc first though. Then same question, cap the engine vacuum from that system? Brake vacuum is from carb and lights from manifold.
Thanks Brent
Le Mans Master
Joined: Mar 2008
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From: Oxford MA-----You just lost the game!!!!
I've never used a vacuum pump before, so I may be way off base here, but I would think that if your engine generates 8" of vacuum, and you have a vacuum pump that generates more that 8" of vacuum connected to the manifold, it will suck air/fuel from the manifold. That can't be good, right?
Scott
Scott
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Joined: May 2014
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From: Washington nj
I've never used a vacuum pump before, so I may be way off base here, but I would think that if your engine generates 8" of vacuum, and you have a vacuum pump that generates more that 8" of vacuum connected to the manifold, it will suck air/fuel from the manifold. That can't be good, right?
Scott
Scott
Le Mans Master
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From: Oxford MA-----You just lost the game!!!!
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From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
I would not assume your system is leak tite,
I would remove all lines to establish your true engine vacuum baseline pressure.
then make a desicision on what yo need to do.
evaluate the problem instead of just throwing equipment at the problem.
I would remove all lines to establish your true engine vacuum baseline pressure.
then make a desicision on what yo need to do.
evaluate the problem instead of just throwing equipment at the problem.
Thread Starter
Advanced
Joined: May 2014
Posts: 81
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From: Washington nj
Thanks
Le Mans Master
Joined: Mar 2008
Posts: 5,948
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From: Oxford MA-----You just lost the game!!!!
Well after I got the vacuum pump hooked still not holding vacuum. I removed all vacuum lines from carb/intake other than vacuum advance. At idle about 800rpm read 10Hg. As rpm increase so does vacuum. So started checking system for leaks as you suggested , after I spent money, probably a waste. Anyone want to buy a vacuum pump? Lights seem pretty good ,but the brake booster isn't holding vacuum. I think I can hear and feel the leak where it connects to the master cylinder. Replacing the booster is not a job im looking forward to. Should I replace the master cylinder as well? Guess I should have went with the hydro boost from the start. I learn the hard way.
Thanks
Thanks
Scott
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Joined: Oct 2007
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From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
Do not open your hydraulic brake system(master Cylinder)
if your brakes are working properly, that opens up more problems.(brake bleeding issues)
to properly test your vacuum components use a hand pump and pull vacuum on each component,
what ever reading you initially pump to say 12 inches.
your component should be able to maintain that vacuum reading for 1 minute, minimum.
if it does not , it is leaking.
a stock engine with everything vacuum disconnected, including power brakes, should be able to pull 12" of vacuum.
if your brakes are working properly, that opens up more problems.(brake bleeding issues)
to properly test your vacuum components use a hand pump and pull vacuum on each component,
what ever reading you initially pump to say 12 inches.
your component should be able to maintain that vacuum reading for 1 minute, minimum.
if it does not , it is leaking.
a stock engine with everything vacuum disconnected, including power brakes, should be able to pull 12" of vacuum.
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