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This topic has been beat to death over the years on here. PCV valves are very helpful on street engines to help ventilate the crankcase. PCV valves flow max amounts at low vacuum(wot) conditions. They flow less at closed throttle(high vacuum) conditions....check it out!

https://www.google.com/search?q=pcv+valv...mp;ved=0CCQQsAQ

Me thinks you have the flow backwards, maximum at idle to part throttle, no or almost no flow at WOT that is according to all the vacume gauges I've used over the years



Take a look at the link I posted. I understand vacuum drops under load....however the flow through the valve increases because of spring tension. They do that because,as you know, the engine produces more blow-by under load. I have posted pics of the flow through the valve on numerous occasions, I just don't have them on this pc. The link has many of the same pics.




The PCV flows a small amout at idle because the vacum is high and it pulls the pintle in very far. It flows the most at part throttle when vacum is a little lower then at idle but it has to have some vacum to pull the pintle valve part the way from the back of the valve because at wide open throttle with no vacum the spring closes the valve to the back of it for no flow at WOT and no vacum. It also does that so on a backfire the valve will seat and keep any backfire out of the crankcase. Ron

Last edited by 383man; 12/01/14 12:53 AM.