PCV valve and a breather or just 2 breathers? 350 chevy
 

Hi all,

I just got a '72 chevy C20 Custom Camper a couple of weeks back, been doing the regular stuff to get it running good and all. The plugs that were in it before were some crappy brand of plugs called Autolite and they had a good big of oil on them i have to say. Prolly was running on 7 cylinders cause it was missing it seemed like. Anyways i put a set of AC delco R44T in it and it runs pretty good!

The truck doesnt have the original 350 in it though. Guy i bought it from said it came from a '76 which i GUESS idk was kinda rebuilt or half-assed i have no idea. Anyways goin back to my question though should i run a PCV valve in the passenger side valve cover and a breather in the driver side? OR should i just run 2 breathers instead?

The motor i kno maybe tired and prolly needs a rebuild but everything seems okay. I've heard that when a motor has alot of Positive crankcase pressure and you have a PCV valve that PCV valve will actually just put the oil that it maybe puking back into the motor and gum up your plugs right?

When i let the truck run and pull the PCV valve when i had it in the motor i would rev the engine and you'd see steam come out from the hole where the PCV was so i ended up putting a breather there and plugging up the PCV hole on the carb.

Though apparently the last owners had the PCV in the drivers side valve cover and the breather on the passenger. IDK if location of the PCV matters at all or not but if it does could one of ya'll explain?

But should i or should i not have 2 breathers? YES no? Good bad?

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

You need the pcv and a breather. They should be on opposite sides to create an air flow through the engine to get the bad stuff out. Without a pcv you run the risk of blowing out seals or actually having an explosion in the crankcase. The engine will also sludge up inside quickly.

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

dont run pcv and expect a great deal of sludge in the engine

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

So you guys say run a PCV still? Instead of having 2 of those push in oil breathers?

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

always run a pcv system. while it may be a "smog" item its actually one of the most important things to engine longevity, besides oil..

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

When worn engine starts burning oil and oil fouling plugs you can switch to hot plugs and leaner AFR.

I concur, the PCV is very useful. I have a road draft crankcase ventilation car; the oil got black quickly until I added PCV.

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

You may not like the autolite plugs but it has been my experience that they last a little longer under situations of fouling. Next time it needs plugs I would go back one heat range hotter with the autolite plug. Delco's are a good plug but seem to foul out a little easier. I used to run autolites on the street and delcos when I went out to play.

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

I use autolite plugs.
One reason is they have a straight forward numbering system.
305E GMC autolite plugs from cold to hot: 63, 64, then 65.
351W F*rd Autolite from cold to hot: 23, 24, then 25.
I run coldest plugs engine health allows.
Autolite and AC delco makes fine plugs.

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

If you actually saw steam coming from the PCV grommet, you've got a bigger problem, because that means there's coolant getting into the top end of your heads. What you probably saw was oil vapor, and that's the PCV valve's job. It takes those oil vapors, which would otherwise be deposited in places you don't want them as sludge, or even become explosive, and safely burns them by sending them through the intake. If you've got oil fouling your plugs, it's probably not from the PCV valve.

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

+1 for the PCV.

I agree with others, too much blowby might be the issue. It could be causing the extra oil (or vapors) to get into the system through the PCV. Deleting the PCV is not the solution. Make sure your PCV valve is good. And consider a compression test.

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

even on a 10 to 1 ratio engine u would put a ocv valve?

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

Yes... any street driven engine NEEDS a PCV. If you're only running on the strip, then no. Then again, even on the strip I ran a MOROSO crankcase evac system on my drag car.

Gary

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

Some hide the PVC why you only see two filters on a nice engine, Buick's had it hidden behind the carb in the intake stock.

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

Another vote for a good working PCV system to suck lost compression (piston ring blow by) out of the crank case.Yes. No rings will be able to seal compression 100%.

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

I dont want to drag this thread out, but Im running a holley double pumper which the power booster is hooked up to the carb cause if i hook it to the pcv valve to it its got barely any vacuum. so tech. ive been running two breathers and no pcv. how would I connect a pcv to a vacuum source? can i split the carb line with a t fitting with the power booster?

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

The pcv and brake booster should have seperate sources. The cheapest easiest way that will probably even net a performance gain is to get a 1 inch 4 hole aluminu spacer with a threaded vacuum port drilled into it. It will be less than 30 bucks. http://www.summitracing.com/parts/trd-2584/overview/

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

Another vote for the pcv. I had an engine that was not driven very much and the oil started to look like it had moisture in it. Thought I had an engine problem but figured out it was from not having any cross ventilation in the crank case from a pcv valve. When I did run engine the moisture could not get out of the crank case. The moisture would collect in the the crank case from the temperture swings and humidity from sitting in the shop. Installed the pcv valve and problem solved. Never did it again.

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

what do people that have power brakes and run a pcv valve do? what did they do w/ stock vehicles that had these?

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

Typical OEM cam produces more vacuum than performance cams. Some hot cam gear heads use vacuum canister to store vacuum. Even OEM, power brakes vacuum port must be large enough to support flow.

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

I did this exact setup with my Power brakes being run out of the back of the Holley 3310 to a vac canister, then to the booster. The PCV is in the 1" spacer with a drilled and tapped port to use for the PCV. Works like a charm.

Gary

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

Hi guys I know this is an old thread but I'm having the same issue. I bought my truck about a month ago and noticed the PCV is connected to the brake booster. The engine has an after market Cam in it. The engine has a breather on each valve cover gasket but I have noticed the oil is sluge and the oil pan gasket is leaking. Should I be running a PCV and if so how would I do this with my current set up?

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

So you are saying that you have a hose from your valve cover to your booster?

Ive always run my PCV to the 3/8" port in the base plate of the carb. I run the brake booster to a 3/8" port in the manifold.

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

And to answer your question of whether or not you should run a PCV, yes. Its been said in a few earlier posts that "anything driven on the street should run a PCV".

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

Aren't we already going over the same thing in this other thread of yours?
http://67-72chevytrucks.com/vboard/s...d.php?t=719052

I think we determined that your PCV is not attached to your brake booster. You have none.

We can help you get your PCV right, but it makes me feel like I have double vision and/or deja vu to reply about the same stuff in both threads. :lol:

Re: PCV valve and a breather or just 2 breathers? 350 chevy
 

Sorry man, I'm just trying to get as much help as I can. Seems like whoever had the truck before me kind of half assed a lot of things so I'm just trying to get the truck right. The help is appreciated.