To PCV or not to PCV

[eyezy]

Hi I have a 78 C10 running a 350 with headers a new Holley Vac Sec 650 4 Bbl with a Turbo 400 & a F@$rd 9 inch. It's staring and running sweet as the plugs look good - However I am wondering if it should be running a Pcv valve. Currently it has a breather on each rocker cover. If I do need to fit one I'm also wondering does it affect the mixture ?
The saying if it ain't broke don't fix it springs to mind at the moment. What do you guys think ?

 

[firebane]

I would be running it.

 

[350runner]

Positive crankcase ventilation... YES you should.

Sent from the dust in front of you!

 

[MadOgre]

Its pretty much a must! Just run a 90 elbow and 3/8 inch fuel line, in place of one of the breathers, over to the base plate on your carb. It just runs off manifold vacuum below the throttle plates. It wont affect anything with carb tune.

 

[MrMarty51]

Its pretty much a must! Just run a 90 elbow and 3/8 inch fuel line, in place of one of the breathers, over to the base plate on your carb. It just runs off manifold vacuum below the throttle plates. It wont affect anything with carb tune.

Does the other breather need to be removed and a sealed cap installed ? ? ?
Just wondering.

 

[firebane]

Does the other breather need to be removed and a sealed cap installed ? ? ?
Just wondering.

A breather is perfectly fine.

Think of a pcv system as a air circulation system for your engine. It helps remove gases amongst other things from the engine and without this.. bad things can happen.

 

[DoubleDingo]

I would definitely put one on.

 

[MadOgre]

Does the other breather need to be removed and a sealed cap installed ? ? ?
Just wondering.

NO you need clean filtered air in one side and vacuum from the manifold pulls it through the crank case to the other side which is then sucked into the intake and burnt through he combustion chamber and out the exhaust.

PCV stands for Positive Crankcase Ventilation

So you can leave the little filter breather on one side or instead run an elbow and hose to a fitting on the clean side of your air cleaner from the location of the filter breather.

If you use the filter breather they do need to be changed as part of regular maintenance if you run a hose and fittings to the air cleaner when you change your air filter you are in effect changing the filter for your case ventilation as well, as the air cleaner now serves the purpose of the filter breather.

I like the air cleaner set up as there is less likelihood of contaminants entering the crankcase.

 

[MrMarty51]

AAAAHHHHHH YESSSSssss, You done awokened a sleeping brain cell, Now I remember changing them little filters.
YES on moving the hose to within the engines air filter, no need for that little filter inside the air cleaners housing then.
If there was any blowby from the cylinders that little filter/breather would oil up the air filter.

 

[NOPHO84K30]

Huh I have a pcv on both valve covers with a t going in to carb base...so its just sucking engine gasses no clean air going in... also what do you guys think of oil catch cans...usefull yes..no..

 

[MadOgre]

AAAAHHHHHH YESSSSssss, You done awokened a sleeping brain cell, Now I remember changing them little filters.
YES on moving the hose to within the engines air filter, no need for that little filter inside the air cleaners housing then.
If there was any blowby from the cylinders that little filter/breather would oil up the air filter.

Yep you got it. The Edelbrock chrome air cleaners come with a knock out and a cast fitting that bolts onto the bottom filter housing. It works really good.

Then you just need a 3/4 inch 90 fitting to go in the valve cover and chunk of 3/4 heater hose to connect the 2

 

[MadOgre]

Huh I have a pcv on both valve covers with a t going in to carb base...so its just sucking engine gasses no clean air going in... also what do you guys think of oil catch cans...usefull yes..no..

SO you are not venting the crankcase with that set up. You need fresh filtered air to go in one side and the pcv valve on the other routed to the carb base.

Im not sure what an oil catch can is?

 

[NOPHO84K30]

Ok ill change that so it gets fresh air in one side and pcv on other side..oil catch cans trap oil in the gasses so the oil dosent go in to carb and dirty it up..

 

[firebane]

If you need a catch can on a stock vehicle you have MUCH MUCH larger issues.

 

[350runner]

Not so....what it traps is oil vapor. I used one a while back on a Durango I had. I noticed it ran a little smoother. Nothing to write home about tho. I could trap a couple ounce every month or so. There are threads that show how to make your own all you need is a air compressor line water separator
http://m.sears.com/craftsman-heavy-...1x000001&kpid=00916009000&kispla=00916009000P