PCV, advantage or not?
 

Is there an advantage, disadvantage or does it make no difference in leaving the PCV valve connected on a stocker?
Does it provide more air to the engine?
Or, should you just block the PCV port in the intake and forget about it?

Re: PCV, advantage or not?
 

a pcv working properly will be closed under wide open throttle

Re: PCV, advantage or not?
 

I've seen fast stockers both ways.

Re: PCV, advantage or not?
 

I have run them both ways and as mentioned above, they are closed at wide open so no difference in performance. However, I think you will see less valve cover "milk" with a PCV. [maybe]

Usually I do not run a PCV but see no problem with doing so.

Re: PCV, advantage or not?
 

I have a pcv valve on mine.

Re: PCV, advantage or not?
 

i run two,and the engine is sealed good ,no dip stick or breathers,havent had a data to say weather if theres a horse power gain gmonde

Re: PCV, advantage or not?
 

I know of someone who tried the two PCV deal, no breathers, etc on an engine on the dyno and lost serious power. The idea is that the PCV valves would make a poor-man's pan-evac, pulling a vacuum on the crankcase. Problem is that like it has been stated, PCV valve(s) is closed at WOT so the idea falls apart. Pressure builds in the crankcase and you lose power.

I have run with and without a single PCV with a breather on the opposite cover back to back. It made no difference except that I get less oil blowing out the dipstick tube when there are two open breathers than when there is one with the PCV. The pressure has to go somewhere, and no matter how well sealed the motor is, there is going to be blow-by.

Re: PCV, advantage or not?
 

Poor-mans pan evac, exactley! If you lost serious power on the dyno, and your blowing oil out the dipstick tube, then you need to work on your ring seal. Serious blowby unloads the top ring and blows oil out the dipstick, causing loss of power. This is one way you guys can check to see if your rings are sealing. A good ring seal will pick up with the "poor mans pan evac"

Re: PCV, advantage or not?
 

Bub's right and you wouldn't believe what I have spent on the dyno with PCV's. The good news is they work. But there's a lot of buts and I'm not going to tell all because my engine builder would kill me!. But I will share that not all PCV's are created equal! That's why there are so many part numbers. I bought from the discount stores and the OEM's. I looked at late model (emphasizing the low drag piston ring models) equipped on small blocks to big blocks to the older stuff. There are more effective ways to find HP, this is just one way to get there.

Re: PCV, advantage or not?
 

what does PCV stand for?

Re: PCV, advantage or not?
 

Positive Crankshaft Ventilation, It's a hose from an intake vacume sorce, carb or intake manifold, that draws air thru the engine to remove water and fumes. What they are discussing here is using this vacume source to create a vacume in the pan by sealing off all breathers to aid ring seal, if it's good enough...

Re: PCV, advantage or not?
 

Bub,

How about running one valve cover with two holes and one with one hole

In the one with one hole you will have a header e-vac, on the cover with 2 holes you will have a header e-vac and a pcv valve + header e-vac through intake valley with baffle so it doesnt suck oil.

Wouldnt this give you good breathing if you couldnt run a vacuum pump as the pcv valve would work great at idle then close WOT BUT @ WOT the header e-vac would be working by pulling vacuum in the heads and lifter valley ??

How much better would a header e-vac work if you had one in the intake too ? With the header e-vac in the valve cover it has to pull from limited area (pushrod holes, drain back holes etc) and as we know oil can get up in the heads and not drain quick so maybe we also cant pull enough vacuum quick enough through drain holes etc. This way with 3 header e-vac's

Any Thoughts ??

Re: PCV, advantage or not?
 

...and how about on a stocker. i don't know about NHRA, but in IHRA we can not run header evac, is there anyway of hooking up the carburator metering block tube that creates vacuum throughout the rpm range to the pcv to create vacuum even at WOT.

Ian

Re: PCV, advantage or not?
 

Sorry about that, my question wasnt about stocker(s). You guys have some tuff challanges in Stock

Re: PCV, advantage or not?
 

What you want here is what I use on Superstock engines, Delco FB101 breathers that have 5/8 hose nipples and I bore the top 3/4 for a brake booster valve that seals when not being sucked on with hoses T'd to the PCV port on the carb. Don't do this to an intake runner as it will screw up that cylinder. EGR valves on tubes in the collectors at 45 degree cut to draw when exh velocity gets up to take over when intake vacume diminishes. the EGR valves on the collectors also seal the same way as the brake booster valves so there is constant vacume in the crankcase...

Re: PCV, advantage or not?
 

All you can do on stockers is intake vacume. If your ring seal is real good than you can use brake booster valves that seal when vacume diminishes and it will maintain nicely.. If ring seal is so so, use PCV valves as they don't seal as well and won't build as much pressure. The main thing here is you don't want any pressure in the crankcase as it will unload the rings and you will loose power, or blow oil out of every orfice that ain't up to the task. which leads me to another important step that you have to pay attention to... You can't have any leaks, you cant build vacumn in the crankcase if it don't seal!!! Test for leaks by slightly pressurizing the crankcase and listen, squirt with soapy water and seal them all up...

Re: PCV, advantage or not?
 

Bub
SHHHH!
No more Top Secret Stuff

Re: PCV, advantage or not?
 

Sorry,,, erase erace erace, delete

Re: PCV, advantage or not?
 

I think you mean....air injection check valves.
A EGR valve injects exhaust gases into the intake as an inert gas to control NOX. Cool the combustion mixture.
Smog test guy (CA) so I had to answer.

Re: PCV, advantage or not?
 

Just to clarify, any pan-e-vac or even open tubes hanging in the wind are NOT legal for Stock Eliminator.
A pan-e-vac is allowable in Superstock and is more effective than a PCV system.

Re: PCV, advantage or not?
 

Any recomendations on pcv valve part numbers? I have always ran one with one breather thanks

Re: PCV, advantage or not?
 

would you mind showing me that in the rules?
damned if i can find it...

Re: PCV, advantage or not?
 

Stock ) Under EXHAUST - Pan evacuation systems prohibited.

Re: PCV, advantage or not?
 

Re: PCV, advantage or not?
 

Bub if you give up any more secrets I am going to have to visit our family in Sanford...


Lol I hope you are well and so is your family....

mark

Re: PCV, advantage or not?
 

sho 'nuff!
i was looking EVERYWHERE else......


just a thought, would it be possible/legal to run the vaccum to the pcv "ported" rather than manifold vaccum?

Re: PCV, advantage or not?
 

PCV , LEGAL or NOT legal when was the last time you saw 2 pcv on a stock engine , maybe one but not two . Just a thought . how does one work . ??

Re: PCV, advantage or not?
 

If your car came with two carburetors what's wrong with two PVC valves?

Re: PCV, advantage or not?
 

Not that uncommon on 1980's carbureted engines.

Re: PCV, advantage or not?
 

Would Ac Delco 746c or 736c be a good choice for PCV valve ?

Re: PCV, advantage or not?
 

So Bub, theoretically speaking, so as not to give any thing away. If the engine is sealed up good and tight, a brake booster check valve could be used in one of the valve covers, a length of sizable hose could be used to connect the booster check valve to the carb, say at the original connection for the PCV connection.

Then lets say this theoretical system could be used to pull a vacuum in the engine and aid in ring seal? say after the car turns on the first amber in the staging process, the driver puts the car in neutral and wings the engine a few times......say kinda like pulling a really good vacuum on a "large can" this vacuum would last long enough to get the car to the other end of the track before crank case pressure exceeded the vacuum,

All in theory of course.....

Re: PCV, advantage or not?
 

DING DING DING... we have a winner

Re: PCV, advantage or not?
 

This is a little off the PCV valve topic, am curious if any one here has tried attaching a PCV valve or e-vac system to the area where the stock fuel pump would go? (chebbie of course) seems like a great place to evacuate from.

Re: PCV, advantage or not?
 

The crank spinning clockwise is throwing oil at that area, the passage to the cam for the fuel pump pushrod is also filling that area, so no...all you will evacuate is oil...even trying to read vacumn from there will give you false readings from all the oil that accumulates

Re: PCV, advantage or not?
 

Well Bub, your half-way there! OK, maybe 3/4 there... :)

Re: PCV, advantage or not?
 

There is one particular Super Stocker that I can think of that has it and he is wicked fast. There has to be a reason to do it.

Re: PCV, advantage or not?
 

this all sounds good except the "...and wings the engine a few times..". i thought the PVC port creates the most vacuum at idle? wouldn't you be better to do the burn out, give the carb a few wacks if thats what your into, then pre stage and stage as close to idle as you can to create maximum vacuum

Ian

Re: PCV, advantage or not?
 

Positive Crankcase Ventilation.......Chris

Re: PCV, advantage or not?
 

Thanks Jeff, but I'm all the way there... At my age, I'm just backin off a little for you guys..

and Ian Hill, part throttle builds the most vacume

Re: PCV, advantage or not?
 

and a PCV valve does not hold a vacuum as well as a brake booster check valve.