PCV or not?

[lewtot184]

These are the types of answers I'm looking for. I don't have a problem using a PCV. I just want it set up properly. Some say the thread should have ended long ago, but with all the squabbling, and unhelpful answers, it can be hard to pull out all the good ideas. So now I know I need to check for a baffle on my aftermarket valve covers. I should block off the breather on the same valve cover as the PCV. I don't need a catch can. I don't want one. It will reduce moisture in the crank case. Maybe stop oil seepage from the engine. Thanks to all who posted useful info. I will give it a try.

if your valve covers don't have baffles there are baffled grommets. I don't know if there is a baffled pcv grommet or not. I use the summit chrome covers on one of my engines. they're baffled and take the 1.25" grommets. I use a push in breather on one side and a big block chevy pcv on the other side and everything works quit well.

 

[383man]

there's no real downside to a pcv on the street. from what I've read here nobody has mentioned water. water is a by product of combustion and can accumulate in the crankcase (water vapor condensation). the pcv can pull the vapors out reducing oil contamination. the pcv can reduce carbon in the crankcase helping to maintain cleaner oil. all engines leak past the rings some; some worse than others. I just don't see a downside for a street car.

Actually I mentioned moister build up in the crankcase back on post # 17 but I really don't think all the post have been read completely by the OP as some things have been said more then once a few times. But it seems the OP is looking for only the answer he wants to hear. Most of us agree its smart and good to run a PCV system on the street. I agree with all you said in this post as I believe most do on this post but I don't know what the OP wants to believe. Ron

 

[383man]

Yea, sorry I should have mentioned that you would remove the hose to the air cleaner. The rest of it makes sense.

Just think about it, when the engine is in vacuum(IE: off throttle) your engine is pulling air in. When you floor it and the engine goes to zero vacuum your drawing the PCV valve open and now the engine is passing all the built up pressure(and oil blow by) through the carb and burning it through the cylinders. So therefore you have no blow by.

When you floor the car the vacuum drops to zero and a spring in the PCV valve closes the PCV valve so you have zero vacuum that wont pull fumes through the PCV valve when floored and the PCV valve is also held closed by its spring when floored. So the PCV valve is not functioning at wide open throttle. The PCV valve has a spring that holds it closed so when the eng is running and pulling a strong vacuum like at idle the vacuum pulls the PCV valve open against the spring. At idle and very high vacuum it pulls it open far enough so it only lets the PCV valve passage be part the way open so it don't pull to many crankcase fumes at idle and wont effect and contaminate the idle mixture to much. At part to 3/4 throttle when it has good vacuum but not the strongest the PCV valve is in the most open spot so it will pull most crankcase fumes at part to 3/4 throttle where it wont effect the fuel mixture as much and wont be noticed much if any at all since you have a lot of air and fuel being pulled into the eng at part to 3/4 throttle. The PCV valve is made to pull its most and to vent the most crankcase fumes into the PCV valve at part to 3/4 throttle. At idle it will pull smaller amounts because the PCV valve pintle is pulled in far enough so the passage is not fully open so it don't effect the idle any. Ron

 

[WileE]

To PCV or not to PCV, that is the question.

 

[furyus]

youn may not have a baffle in the valve cover under the pcv.

Ok, I checked, and I do have a baffle under the PCV. Also, I plugged the valve cover breather opening that was on the same valve cover as the PCV. So now, I should have positive ventilation. My last concern, is I reconnected the PCV to the only available vacuum supply, which is in the back of the intake (Eddie RPM), on the runner, and the fitting also has a small tube that goes to the heater control tubing. The carb is a Race Demon, and doesn't have a PCV fitting. Also, I have a drop base air cleaner on it now, so no spacer with a port. Will see how it works. Might still need a catch can.

 

[lewtot184]

Ok, I checked, and I do have a baffle under the PCV. Also, I plugged the valve cover breather opening that was on the same valve cover as the PCV. So now, I should have positive ventilation. My last concern, is I reconnected the PCV to the only available vacuum supply, which is in the back of the intake (Eddie RPM), on the runner, and the fitting also has a small tube that goes to the heater control tubing. The carb is a Race Demon, and doesn't have a PCV fitting. Also, I have a drop base air cleaner on it now, so no spacer with a port. Will see how it works. Might still need a catch can.

it's better to have the pcv connection into the plenum or carb base. keep an eye on the spark plug that the intake runner feeds. I've seen them get wet when a single runner is the only vacuum source.

 

[oldbee]

You’ll still be better with a PCV IMO.