Diesel Place banner

1 - 6 of 6 Posts

·
Registered
Joined
·
23 Posts
Discussion Starter #1
I need a vacuum pump to use for a pvc system on a 64 Nova [421 stroker with an Enderle intake]I'm building. I was thinking of using a diesel vacuum pump like the one on my 95 Suburban. The pump on my truck gave up the ghost a long while ago and I put in a Turbo Master kit. I know that the pumps (should) put out 25 inches of vacuum at idle but does the vacuum reading change as the rpms change? For my application I would need to reduce the pulley speed at the pump for two reasons. One the rpm range of the engine versus a diesel and two, I only need aprx. 5 inches of vacuum at idle and 10-15 at a higher speed. There are pumps made for racing that produce vacuum but they aren't recommended for the street and they are very expensive. Since I can't measure my dead pump, does anybody know the vacuum readings with regards to rpm.
 

·
Registered
Joined
·
163 Posts
I'm pulling my vacuum pump and won't be installing it again (Turbomaster). It works, but I can't tell you what the #s are. IIRC, it pulls 20" of vacuum at idle. You might need a very large pulley to get a reduction to 5".

PM me if you're interested in buying the vacuum pump. It has ~145k california highway miles on it and looks clean.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #3
Thanks for the offer Steve but if I go this route with a pump, I'll be getting a new one and polish it up before mounting. This engine compartment if it's anything like my 65 Chevy II will be getting a lot of people looking at it and taking pictures. Both drver and driven pulleys would be custom made. I would think a 60% reduction in speed from what the factory ratio is, would be a starting point. Anybody have any info on vacuum readings?
 

·
Registered
Joined
·
6,945 Posts
Is that 5" H2o, or 5" hg?

And is the crankcase\valve cover volume sealed?
 

·
Registered
Joined
·
23 Posts
Discussion Starter #5
That would be 5" hg. One valve cover would have a breather and the other a pcv. Typically a gas engine will have high vacuum at idle, slightly less at cruise and way less when pushed to wot. I would think that ideally an engine would benefit from less vacuum at idle and more as the rpms increase. I'd be happy with either. Stack injection produces a small pulse of vacuum per stroke at each port. You have to bring a vacuum line from each port to a vacuum manifold, then from the manifold, a vacuum line to the pcv. Even then the vacuum signal isn't very strong and with the cam I'm using, weaker still. With the last engine I had, the dipstick would pop up at highway speeds because it couldn't get enough ventilation.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #6
TTT.......with a picture(old engine)



 
1 - 6 of 6 Posts
Top