65cutty

I have 75 350 that am wanting to know if I run a oil breather cap on the oil fill tube allowing the eng internal pressure to escape then do I still need the pcv and valve cover breather?am wanting to install the built alu valve cover's that have no provision's for the breather's or pcv. thanks in advance.......jim

joe_padavano

You want to run a PCV valve. If you choose not to drill a hole in the valve cover, consider going to the intake the way the W-30 and early 70s 4 speed cars did. Some Olds intakes already have a boss where the tube would go, but if not you can usually drill a hole in the web between the water crossover and the front intake runners and install a grommet. DO NOT drill into one of the runners.

65cutty

BUT JOE I HAVE AN ELDERBROCK INTAKE ON THE 350 AND ARE WANTING TO RUN THE ALL ALUM FABERCATED VALVE COVER'S THAT DONT HAVE PROVISIONS FOR PCV OR BREATHER THOUGH I DO HAVE THE OIL FILL TUBE WITH A BREATHER ON IT, STILL NEED THE PCV?

The Stickman

Well let's clarrify things here a bit. I know everyone says to run a PCV. But do you run that in one valvecover and none in the other? Or a PCV in one and a breather in the other for crossflow?

joe_padavano

You need a breather someplace in the crankcase. That can be the oil fill tube, for example.

65cutty

OK, I HAVE A BREATHER IN THE OIL FILL TUBE NOW. SO WITH THAT I CAN INSTALL THE ALUM VALVE COVER'S THAT HAVE NO PROVISION'S FOR PCV OR BREATHER AND BE OK WITH CRANKCASE PREASURE ? /> T

smcurro

The PCV valve has nothing to do with balancing the pressure within the crankcase. Although it does provide vacuum, the purpose of the pcv valve is to remove combustion gases from the crankcase which result due to blowby. In order for the PCV valve to function properly there also must be some type of breather for fresh air to enter through, however, the use of a breather alone is not enough. You must use a pcv valve system of some type in order to remove blowby from the crankcase because this blowby contains some unburned fuel which can potentially wash out bearing surfaces such as the cam and lifters. Without a PCV system the oil must be changed very frequently in order to not allow the blowby contaminants to build up.

joe_padavano

No, what I was trying to say is that you need the PCV in one of the valve covers or in the intake and you also need a breather of some type, either in the other valve cover or in the oil fill tube.

88 coupe

From: http://www.wisegeek.com/what-is-forum-etiquette.htm

Norm

65cutty

88coupe, didnt realize that caps was a screaming at people thing but will refran using it, not very good at this computer thing, am sorry if Ive insultated anyone...