crankcase evac

[Marv D]

Originally Posted by LONGHAIR

From what I understand there really isn't an electric pump that can make enough vacuum to do anything. The Corvette pump will only pull about 1.5" and there is a Pontiac version that will pull around 3". That is not nearly enough to do anything. The regular header evac systems pull roughly twice that ........

I was reading about that 1.5" and 3" and was thinking that exact thought. My header evac will pull 5" with a 1300rpm idle, open exhaust and LONGtube headers. On a street truck through legal exhaust it's going to be lower, but just as effective as a 3" electric pump. I'd think,, and as long as you throw those junk MrGasket push-in breathers away, and replace them with good Mopar breathers (that don't leak like a sieve like the MrGasket junk). Your going to make enough vacuum to keep the seals and all nice and dry anyways. Maybe not enough to help ring seal that much, but every bit helps. ANY vacuum in the crankcase is better than pressurizing the crankcase IMO.

I put a Aerospace vacuum pump on the Nova and pull 10-12" from 6000rpm up (shift at 6800 and trap at 7200). And to be honest, haven't seen any significant increases in power / ET. Mind you the pump went on just as things got stinking HOT around here, but ET's this summer are no better than last summer in like air. My machinist said he sees roughly 30-40HP on a 800HP wetsump motor, and 40-60HP on a drysump high vacuum motor. But dyno HP and what I'm seeing on the track doesn't seem to jive. One big problem you run into with high vacuum is piston pin gaulling. Not sure the dynamics of what all goes on, but the piston pins take a real beating from what everyone tells me. So be carefull in what you ask for,, too much vacuum can cause more headaches than too little. Know of one high RPM motor that was making BIG vacuum and he sucked the Steffs aluminum pan up against the oil pickup,, NASTY results!!!

[69trk]

buddy of mine just put two on his with a guage and some kind of regulator, but he says on his guage that each pump is making 5" of vacuum. He's taking his car to dyno and to the track sometime this month to see what kind of numbers his car will make with and with out the pumps. He's a mustang nut and i guess the mustang guys are doing this. His car ran in the low 9's before he built this new motor. I'll post some numbers as soon as i get them from him.

[nxtruck]

Originally Posted by Marv D

I was reading about that 1.5" and 3" and was thinking that exact thought. My header evac will pull 5" with a 1300rpm idle, open exhaust and LONGtube headers. On a street truck through legal exhaust it's going to be lower, but just as effective as a 3" electric pump. I'd think,, and as long as you throw those junk MrGasket push-in breathers away, and replace them with good Mopar breathers (that don't leak like a sieve like the MrGasket junk). Your going to make enough vacuum to keep the seals and all nice and dry anyways. Maybe not enough to help ring seal that much, but every bit helps. ANY vacuum in the crankcase is better than pressurizing the crankcase IMO.

I put a Aerospace vacuum pump on the Nova and pull 10-12" from 6000rpm up (shift at 6800 and trap at 7200). And to be honest, haven't seen any significant increases in power / ET. Mind you the pump went on just as things got stinking HOT around here, but ET's this summer are no better than last summer in like air. My machinist said he sees roughly 30-40HP on a 800HP wetsump motor, and 40-60HP on a drysump high vacuum motor. But dyno HP and what I'm seeing on the track doesn't seem to jive. One big problem you run into with high vacuum is piston pin gaulling. Not sure the dynamics of what all goes on, but the piston pins take a real beating from what everyone tells me. So be carefull in what you ask for,, too much vacuum can cause more headaches than too little. Know of one high RPM motor that was making BIG vacuum and he sucked the Steffs aluminum pan up against the oil pickup,, NASTY results!!!

Marv,
I've tried the header evac setup several times, both on different engines and with two different sets of headers. Mind you, I always ran an exhaust system of some kind, but I never could get any satisfactory results with them. On one set of headers, I even tried the evac tubes in a couple different spots and different angles. Now, I never tried them without any mufflers, and they may have worked had I done so. I have a friend that races a '69 Camaro in SS/JA and he has always had good luck with his evac setup. They aren't allowed to run vacuum pumps of any kind, so the evac tubes were his only option.
You are absolutely correct about having too much vacuum: most guys run between 10"-15" and it seems like anything over about 15"-16" will start pulling oil away from wrist pins, among other things.
Who knows; if this vacuum pump setup that I'm about to try doesn't pan out, I may revisit the evac tube setup and relocate them further downstream, past the mufflers, and see if I can make them work with an exhaust system. My exhaust system isn't much; about 2 ft. of 3 1/2" pipe into Dynomax Race Magnum mufflers and about 8" of tailpipe after that. Apparently, the evac tubes have to have NO backpressure in order to function correctly.
BTW, Congrats on your PINKS showing!! Way to represent the 60'-66' Chevy trucks!!

[Rodms]

When I fired up the first time it blew dipstick out and oiled up everything real good no rust starting under the hood