PVC and catch can question

[Jeff Stout]

If using a PVC can I run a catch can. Having blue smoke out exhaust when using PVC. Remove it and smoke goes away. For stock class

[Lew Silverman]

I'll make an assumption that we're talking about a "Positive Crankcase Ventilation" (PCV) valve here, and that it's picking up enough oil to make your exhaust emit a blueish fog. There are a few things I've tried to stop just what you're describing - one was a baffle underneath the grommet holding the valve to keep anything but vapor away from it OR some of the early Mopar's had a remote valve that sat in a hose mid-way between a plain plastic elbow and the vacuum fitting screwed into the intake manifold. Both seemed to work nicely at keeping the oil from entering the intake system. Good Luck!

[Jeff Stout]

Correct. I built a baffle in valve cover and it didnt completely solve the problem. Spark plugs look better when disconnected. Can't say car has ran better or worse, with or without PVC.

[SDT1DYI]

I wrote to our Divisonal tech director as to installing a Mororso type oil seperator. Was told, not legal for stock if it did not come as an OEM item for the year and make of your vehicle in Stock Eliminator.
Baffles help, but if there's no performance gain, why do this?
The question to answer is , how much vacuum does the motor hold on the starting line and what is it down track?
All the comp guys run one or two vacuum pumps. Increasing crankcase vacuum is proven to make more power.
Benifits are diminished with lower Hg vacuum numbers. Besides ring seal, all the engine gasket sealing surfaces and crankshaft seals effect crankcase vacuum. There are special crankshaft seals designed for vacuum service as well.

Steve Teeter. STK/SS 620

[Ralph A Powell]

I could get a consent 5” with header only on my car. Reason I know is I had a vacuum gage right next to my tach so I could read it all the way down track but the engine was very well sealed ( no vacuum leaks)

[Jeff Stout]

I was hoping for better ring seal and performance. But contaminating the top side I feel is hurting the potentail gain. Looks like the catch can being not legal is answered. Thanks for the replies.

[GTOMayhem]

I understand PCV valves allow varying degrees of vacuum depending on engine application. There is even an adjustable one. Someone with more knowledge than me will need to fill in some details, though. Also, I think Billy Nees just runs a vacuum brake booster check valve as a PCV. He will need to fill in the details.



Rick Thomason
GTO Mayhem

[SSDiv6]

Jeff,

You have options.

You can put a Wix crankcase breather filter, P/N 46978, between the valve cover and PCV or breather.

https://www.wixfilters.com/Lookup/Pa...px?Part=138224

Another option are Speedway Motors PCV Grommet Baffles.

https://www.speedwaymotors.com/PCV-G...Caps,7332.html

Or, weld tubes on the valve covers and put breathers.

[SDT1DYI]

A PCV " system" is best installed when your building the engine. As I mentioned, all the sealing surfaces of the engine need to be addressed. Then it's best to hook a vacuum pump up to the engine while it's on the stand. Draw it down to say 15 Hg. Then shut the vacuum off. Watch your guage piped into the engine vacuum area. Does it drop quickly? If it does then you have gasket issue. Valve cover gaskets are a good place to start. Once you know the motor is sealed up, your vacuum loss is ring seal......
It's a lot of work and helpful if your engine produces higher vacuum conditions , like in 2 barrel combinations


Steve Teeter STK/SS #620

[Jeff Stout]

Originally Posted by SSDiv6

Jeff,

You have options.

You can put a Wix crankcase breather filter, P/N 46978, between the valve cover and PCV or breather.

https://www.wixfilters.com/Lookup/Pa...px?Part=138224

Another option are Speedway Motors PCV Grommet Baffles.

https://www.speedwaymotors.com/PCV-G...Caps,7332.html

Or, weld tubes on the valve covers and put breathers.

Thanks Joe. I ordered the grommets from Speedway