Sbc Pcv

[Bruce7419]

Regarding 1966 327 engine, I have aftermarket valve covers with breathers, edelbrock intake manifold and carb. I am trying to convert to stock valve covers and intake with oil filler tube, with a closed PCV and a sealed cap. Reference 1966-7 327 Chevelle or Corvette engine closed PCV system which has a ventilator breather tube in rear engine that connects to bottom of base air cleaner.

Anyway Edelbrock carb has vacuum port in front to connect PCV at oil filler tube. No problem.

Since I don't have stock air cleaner with breather pipe then do I need road draft breather tube in this closed PCV system?

[burger]

Bruce,

That was really tough to read.

Anyway, here's what I did and it works well. Use an oil fill tube on the front with a breather in the cap. Drill and tap the back of the manifold (over the valley NOT into an intake runner) for a 1/4 NPT fitting. Then, purchase a '65 Corvette PCV valve. It has 1/4 NPT threads on one side; screw it into the hole you just made in your intake. Connect the other end of the PCV valve to your carb and you're golden like a shower. Check out the pictures if this doesn't make sense.


Hope this helps,
Ed

PS- I have a 1/4" NPT street elbow behind the Corvette PCV valve. This was just to help with the hose routing and isn't necesary.

[Bruce7419]

Ed,

Thanks for sharing your idea!

I prefer "closed positive ventilation" which uses a "sealed" cap and pcv on the oil filler tube. There is no breather cap on tube. PCV is connected to vaccum port on carb.

My questions:
(1) With "closed" pcv, do I need to vent (breathe) crankcase into the carb or outside air (road draft)?
(2) My pictures are 2 mb so how can I reduce size so they can be attached on this website for you/all to see?

My car's name is Christine and she would appreciate any help!

[yekoms]

Bruce,
For a pcv system you need filtered air into the crankcase area to replace the air that the carb vacumn is taking out through the pcv valve. Chevy pcv systems did that through the breather cap on the fill tube,later they ran a hose with a small filter inside the base of the air cleaner. If you run a hose to the air cleaner inside of the air filter element you don't need that small pcv filter.

Bruce is correct by going into the valley under the manifold. I think that some early Chevies used the fill tube for the pcv connection also.

When using the threaded or inline pcv valve make sure that the air is flowing through it in the correct direction. Pcv valves are a one way valve so that a backfire does not get into the crankcase. I don't know about 65 Vettes but on all of the Two barrel Rochester Chevies the threads went into a fitting on the carb.
Sorry if this is to long and I don't want to sound like a know it all but, I have a hard time typin' what I'm tryin' to say.
Have fun,Smokey

[Bruce7419]

Hey Smokey, thank you!

I understood everything you said!!

One more question...How to shrink pictures from 2000 kb to 60 kb so you all can see my topic???

[yekoms]

Hey Bruce,
I just read my blah,blah and your post again. I ment "Burger" is correct. Sorry Burger.
OK now I got in my head what you were askin'.
Up untill 68 Chevy use the road draft area as the connection for the pcv valve.
Pcv valve was on the carb with a hose to the road draft thing. Under the manifold connected to the road draft area is a can lookin' oil separator. Ok now I got the suck side figured out.
With that system they used a breather type oil fill cap for air in.
The problem starts when we start mixin' old with new pvc systems.
You are hookin' the pcv vavle to the fill tube. So you need filtered air in. Hey Bruce Do I got it right now?
How can we move this thread to the HANB to get it out of the "introduce yourself area?"

[yekoms]

Bruce, Sorry man i can't help ya with the computer shit. I can barly do this typin' stuff...
have a good one.Smokey

[Bruce7419]

Smokey,

Thank you again...you understand.

I don't want breather caps on valve covers nor oil filler tube.

Also because my stock air cleaner with breather pipe (goes into bottom of base a/c) will not fit Edelbrock carb with 5.25 inch air horn diameter, I decided to buy 55-61 SBC road draft tube. This tube connects to the oil/ventilator can under the intake inisde the valley at back of engine. I will put a flame arrestor screen on the external open end.

-Christine (AKA Bruce)

[yekoms]

Yep Bruce we are finally on the same page. You are just doin' the Chevy pcv thing in the opposite flow direction. Some sort of screen in the tube would be good to keep out birds,frogs,small road kill,dust and mud.
I just got another idea. A big ugly lopey idle cam would have less vacumn and lessen the Christine's chances of suckin' in dirt.
Have a good one,Smokey

[Burny]

Yep Bruce we are finally on the same page. You are just doin' the Chevy pcv thing in the opposite flow direction. Some sort of screen in the tube would be good to keep out birds,frogs,small road kill,dust and mud.
I just got another idea. A big ugly lopey idle cam would have less vacumn and lessen the Christine's chances of suckin' in dirt.
Have a good one,Smokey

Hey, Don't mean to hijack this thread, but I've seen a couple posts lately on the PCV issue and smallblocks that got me wonderin' I got a 66-67 283 with and Edelbrock intake and 4 BBL carb and breathers on both valve covers. Do I need to run a PCV valve on this setup?

[yekoms]

Hey Burny,
You ain't hijackin' anything. This is what these great sites like this are all about. I'm just glad that maybe I can help someone out And if anybody else has any other ideas or info please speak up.
The crankcase gets pressurized from leakage past the piston rings. So the crappier that the ring seal the more pressure you end up with. The crank assembly spinnin' just makes windage.
Without a vacumn source to suck the pressure out it just pushes its self out. Pushin' some oil with it.
The pcv system just sucks out some of that pressure when the engine vacumn is higher than the crankcase pressure. Mostly at lower engine speeds.
Some race cars use the header collectors as a vacumn source that works at higher engine speeds. Some use vacumn pumps to suck to pressure out.
You really don't "need to" cause you have breathers to release the pressure.
You do need at least breathers to vent the pressure or there would be a problem with seals, gaskets leakin'or engine smokin' etc.

Have fun,Smokey

[Bruce7419]

Finally here's a picture!