pcv
 

hey zipper.. i think i understood you as saying that you cant run crankcase evac to headers if you run through mufflers. if this is true, why cant you?. i never heard of this and im glad to know this if it is true thanks art

Re: pcv
 

It's because the mufflers create back pressuse in the headers even with flow thru mufflers. You can if just driving around on the street without taking the RPM'S up but when you do you will find every possible leak that the engine may have, it will even blow oil out around the push in evac connectors on the valve covers. The evac system is designed to work with a vacuum in the headers and you lose that with mufflers due to the back pressure that they create.

JMO

Zip.

This is a great thread,
I am running 3" from the collectors to the back bumper with no mufflers but through an 'X' pipe just after the collectors.
Question; Would the exhaust mounted evac system work with collector 'baffles' installed or would they ALSO bump up the back pressure too much?
430 Big Block Mopar turning 5K - 7K at full talk for miles on end.

There's only 1 way that you can run the header evac system with mufflers or baffles that i know of and that is to install the tubes behind the mufflers or the baffles, they will not be as effective as collector installed without mufflers or baffles, but will work. If you've ever blown air across a glass of water you know it will suck the water out, the more air you blow the more it suck the water out, same theory with the header evac system.
In the old days we didn't use header evac systems we just ran about a 4" tall tubes and breathers, i've run blower motors that way in the 60's. Now aday i run burn down tubes 1 1/4" dia into a 1 gal catch tank with the blown alcohol motor with zoomies, but i run a 1471 on a small motor.
I've got a set of zoomies with evac system plumbed into all 4 tubes on each side but i don't think i will use them. I bought them from my friend up in Oregon with the Willys convertable.

Zip.

What about useing 6" straight thru mufflers bolted right to the collector? :?:

I doubt if a 6" straight thru muffler would have any effect on the evac system when bolted straight to the collector. i know that some tracks and some classes specify that you have to run mufflers and those types qualify as mufflers.
A good example is the 66 Biscyne with the 468" motor that i built, he runs on the street with some oval 18" mufflers bolted to the headers and it gets by the law. But he tried to run at Baton Rouge last yrs, spraying a 200 shot of nitrous. The car slowed down to 10. teens, and blew so much oil out it took an hour to clean the motor and engine compartment. Next pass we unbolted the mufflers and it ran 9,77 @ 138 and change. The car is really heavy so the engine is under load for the full 1/4 mi.

Zip.

Another reason for not running a header evac system with mufflers is because of the accumulation of oil fumes in the headers (pooling in the baffles or absorbing in to the fiberglass matting) can cause an expolsion/fire hazard. Anyone else ever heard this? I'm not saying it's 100% true,but it does kinda make sense I suppose