Vacuum pump help

[HR9121]

I've been told that when installing at vacuum pump on a motor with a 2 piece rear seal that you have to turn it around backwards. Not sure if this is the case or not but hoping someone up here would know for sure. Thanks for any help or suggestions.

[Bill Baer]

Cooter
I run both of crankshaft seals and the cam seal (Jessel belt drive) in the normally installed configuration.
But I don't know how much vacuumn I am making or how much air inlet leakage their is either.
I do know that on the Dyno it was good for a disappointing 13 HP my Engine builder has seen as much as 40 HP gain but in those cases they used a different piston ring combination and turned the vacuumn pump faster. In my case it's keeps the alcohol from milking up the oil which was what I had in mind anyway.

[HR9121]

Thanks for the info Bill. My problem is for some reason from time to time when I stage and go to the mat it wants to squirt a little oil past the seal. Doesn't happen everytime but gets worse in later rounds when everything gets heated up I guess.

[Rick Bailey]

Good guestion, and I've heard that about the seal myself. I'm going to get my first experiance with a pump myself.

But i'll take a stab it on your deal of it leaking. considering the seal is in backwards the motor, just before WOT has some positive crankcase pressure therfore blowing out a little oil..... then when you deck the motor it begins to built vacum and no longer leaks....

I supposed this could be the case no matter which way the seal was.....

let us know....

[Chuck Westcott]

Felpro makes the double lipped seal for that purpose. When we dynoed my Motor we played with the vac pop off and finalized it at 14 in. Why ? Because that is when the Oil Pressure began to spike. Also the HP peaked at 18 to 20 in, but in my style racing I'd rather have consistancy with Vac and Oil Pressure. So don't just throw a Vac Pump on there and expect huge gaines with out determing where you need to pop it off and what ring package you have. That could provide issues with wrist Pins as well as Bearings and leaks. If I were running Comp with 0/5 oil and a very low tension ring package that would be a different story. I'm not an Engine Builder, but the Guy's that do mine are among the best in the business.

[pmrphil]

The Fel-Pro seal is the viton one, it's quite a bit stiffer than the normal silicone seal and should be installed in the normal fashion - I think the number is 2902, but double check to make sure.

[Tom Goldman]

Chuck's got it right.
Leave the trick stuff to the COMP racers.
I've run a vacuum pump for over 16 years and never had any problems pulling 15-16 " vacuum when all the other leak points are sealed up.
Fuel pump block off plates, distributer gaskets , manifold corners are prime leak culprits.
If your engine previously had minor oil leaks,don't expect to pull much vacuum .
HP gains are relative to ring packages ,end gaps and bore condition .

[HR9121]

Rick I really didn't clarify that I haven't installed the vac pump yet I was actually going to in hopes that it may help me with my problem. I'm not really trying to gain hp just trying to help with some little leaks that are commonly associated with these high compression stroker motors. I appreciate everyones input and suggestions. Another question that comes to mind after reading Chuck's post is if you get too high of a vacuum could you run into some lubrication problems, possibly pushing oil away from the pick up. This is a wet sump application.

[Bill Baer]

Cooter

The guys I know who have had wrist pin problems are spinning the vacuumn pump faster than 1/2 crank speed and using dry sump systems in some cases they need to disconnect the pump during warm up.
They also with wet sumps see a reduction in oil pressure due to the reduced inlet pump pressure.
I have had no such problems.
Putting a vacuumn pump will reduce and or elimate almost all of your oil leaks, however the vent on the oil breather tank will mist a little oil when the oil is hot, it's no much but to me it's a little annoying.
I too use the felpo crank seal.

[HR9121]

Thanks Bill for the info, very helpful now if I can just get time to install it.