View Full Version : PCV valve ideas??
BigBlockOlds
06-12-2007, 06:36 PM
Anyone know of a trick way to mount a PCV valve? Here's a picture of the engine I'm working on and you can see the weld in bungs I have in the valve covers:
https://static1.pt-content.com/images/pt/2007/06/Enginetrans-1.jpg
My plan is run a vent line from one valve cover to an oil overflow/catch can with a breather. The other would be for the PCV valve. I'm just having a hard time finding something to match the rest of the engine.
The entire engine is going to be a silver/chrome/polished aluminum look with Russel Endura fittings.
Thanks for the help,
Adam's 55 Chevy
06-13-2007, 09:44 AM
If both sides are going into the catch can and you have a breather on that why use a PCV valve.
GetMore
06-13-2007, 04:38 PM
You shouldn't need to run a catch can on the breather, as it should never have positive pressure.
You will need to run the PCV into the intake somewhere.
I think it might be a good idea to swap sides on the valvecovers. I think that under acceleration you will have a lot of oil vapor pushed toward the back, and therefore pulled into the intake.
BigBlockOlds
06-14-2007, 04:08 AM
Its been my understanding that you should run a PCV valve to help the rings seal better?
The plan was that just one side was going to go to a catch can and the other would be hooked into the intake with a PCV valve located in line.
If both sides are going into the catch can and you have a breather on that why use a PCV valve.
Thanks,
MonzaRacer
06-14-2007, 08:31 PM
If both sides are going into the catch can and you have a breather on that why use a PCV valve.
Well lets see how about ring flutter, oil conmsumption, oil leaks ,blowing out gaskets.
NEVER run an engine over a long period of time without positive crankcase ventalation
No matterhow free you thing a dual breather set up is the crank case WILL get preasurized.
As for me I would order up a PCV from AC delco with a nipple on both ends CV 781 I believe is the number but you have to remove the elbo and just run it inline in 3/8 hose. Then you can use a larger piece of hose or split tubing over it to hide it.
Lee
Adam's 55 Chevy
06-15-2007, 03:51 AM
The crank case will become pressurised regardless due to ring seal. If there is no ventilation in the system regardless of what it is then that pressure will cause oil leaks and gaskets to blow as described. A breather on the valve cover lets this pressure escape just as a PCV valve does. In 25 years of running hi-po V8 engines including a blown dragster I have not had any adverse effects from having breathers only.
I agree with Adam. I've run without a PCV valve for many years without any problems. They only scavange when their is vaccum part throttle or idle. Under full throttle they do nothing. Why screw up a good fuel/air mixture with a vacuum leak? Don't need one unless you must pass a smog inspection. Just vent the engine properly and you'll be fine. I've never had increased oil consumption, oil leaks or blown gaskets! In fact I had increased oil consumption with one no matter where I mounted it or baffled it.
Skip Fix
06-21-2007, 03:53 PM
But that vacuum leak at idle may do the same thing as drilling holes in your butterflies to allow some bypass air.
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