Engine breathing
 

When it comes to letting your engine breathe via pvc valve, oil breather tubes, etc. what is the standard I.D. of the hoses coming out of each valve cover? I have a supercharged 440 which will be running soon and was just curious. I have -8 lines coming from both valve covers going into a breather tank. This ok?

I'd recommend -12 or equivalent.

-12 huh? I can see if you were running a vacuum pump to seal the rings better, but for my application? Is there a formula for figuring this out based on cubic inches vs the amount of air that needs to be bled? Thanks Vegas.:thumbsup:

I don't know of a formula but I think #8 is too small for breather hoses. I used #12 on mine.

A supercharged application with that may cubes calls for at least 2 -12's in my opinion. That is, unless you just plan on putting around to car shows. :unibrow: Excessive crankcase pressure has no positive side effects. You lose power and seals leak. Remember, this is positive pressure not negative with a vacuum pump.

Just to be sure.... you said you're running a PCV valve? I would ASSume then that it's got vacuum to it? OR are you just running -8 VENTS to a breather can?

My brother in laws blown - dual carb - 383 - uses a "normal" PCV to the base of one carb for vacuum - and of course - a vented breather in the opposite valve cover.... and this works fine for a street driven blower motor. If he was hammering it on the strip - then I'd go with Todd on the -12 vented lines to a breather catch can.

No PVC valve just the breather tubes and catch tank. Guess I'll order up some -12's. Thanks guys.