Crankcase evacuation

[moparmaniac59]

Hey there my fellow Mopar nuts!  Been a while since I've posted here. I've been in the background lurking but decided to post some Mopar related stuff that has helped me out. Chryco, you can correct me if I am wrong here. Big block Mopars are notorious for having issues with crankcase evacuation and it can starve you of your horsepower. I have a stroked 440 which is stroked out to 543 and this has been a problem to me. I have read a lot of good articles on the issue and had considered going with a double catch-can set up. A very knowledgeable friend of mine convinced me not to and commented that it would smoke and be messy.  I had used a K & N type filter on one valve cover and a billet aluminum on the other with a 3/8" vacuum line. It wasn't enough & caused a smoke issue (carryover). At one point I had actually blown my rear main seal due to too much crankcase pressure; which this is one of the problems that can occur with improper crankcase evacuation. My buddy told me you have to go bigger! Here's what he suggested and let me tell you it works well. Get a PCV valve for a 1966 Covette. It's an in-line PCV (5/8" inlet nipple) and can be used in any position (it's spring loaded). A lot of racers use them. Run a line from a large breather. I use a Mr. Gasket that has a 5/8" nipple. Drill a dedicated port in the intake plenum. DO NOT go to an intake runner as it will cause that cylinder to run lean! Go to the plenum before it splits to the individual runners. So I drilled and installed a 3/8" nipple and fit a 5/8" tygon tubing from the breather and installed the in-line PCV in the middle. No smoke, problem solved! Now no crankcase pressure issues! See the attached picture. Feel free to ask questions, but this is a very inexpensive set-up and solves the PCV and evacuation issues! 

                                                                                         Matt B.

[jimynick]

Good info! The KISS principle works for me. 

[Chryco Psycho]

makes sense to me too , I blew a valley pan in 1/2 before using the headers to evac

[Racer57]

Ok, I gotta ask a dumb question......... Do the plugs show any sign of oil ?

[moparmaniac59]

My plugs never looked bad. There wasn't enough carryover to oil foul them.


                                                                                             Matt B.

[jhaag]

Are you running a breather on the other valve cover to let fresh air in?

[moparmaniac59]

Yes, I have a K & N type breather/filter or the driver's side valve cover. It allows air in 360 degrees around the sides of the breather. It wasn't very expensive and is actually pretty nice and works well! 


                                                                                                  Matt B.

[cudabob496]

makes sense to me too , I blew a valley pan in 1/2 before using the headers to evac

so, was engine machined, so that you were getting too much blowby past the rings?

[Chryco Psycho]

yup it was perfectly machined but @ 7000 rpm it made pressure anyway  , no oil loss 12 qt pan fully baffled with a lip under the rear main  to prevent slosh up the back of the engine , I used a tee system where the PCV valve contolled the pressure at low RPM & the header evac took over with rpm  this engine never had an issue raced for 9 seasons shifting 7000-7200 + thousands of miles of street driving 

[cudabob496]

yup it was perfectly machined but @ 7000 rpm it made pressure anyway  , no oil loss 12 qt pan fully baffled with a lip under the rear main  to prevent slosh up the back of the engine , I used a tee system where the PCV valve contolled the pressure at low RPM & the header evac took over with rpm  this engine never had an issue raced for 9 seasons shifting 7000-7200 + thousands of miles of street driving

seems it would not be hard to install some kinda pressure relief valve in the valley pan.

[Chryco Psycho]

I did , I took the pressure from the valve covers down to the headers with check valves worked flawlessly

[moparmaniac59]

A lot of folks never consider that the piston pumps on both sides and the crankcase will indeed build up some pressure and if not properly evacuated can cause problems like a reduction in horsepower to blowing out the rear main seal, or like Neil did....split a valley pan!  The issues I had with using too small a vacuum line is akin to the garden hose principle. Turn on your garden hose and attach a drinking straw to the end and what happens? You have an increase in velocity and it sprays water across the yard; run that same garden hose into an 8" pipe and it will trickle out. The hose I had that was too small & caused an increase in the velocity of the vacuum flow and brought more oil carry-over from the crankcase into the intake where it cause the oil to burn/smoke. So by going from 3/8" vacuum line to the larger 5/8" tygon tubing I reduced the vacuum restriction and thus reduced the oil carry-over from the crankcase. It solved the excessive crankcase pressure issues. It's getting that right balance. 


                                                                                                 Matt B.

[Grec]

The guy that built my motor suggested I run pop-in breathers on both sides vs. the stock breather and PCV...

But I'm hesitant:

1) The thing reeks without the vapors going back through the motor
2) I'm getting oil residue on my valve covers from the venting on the bottoms of the breathers
3) I want it to look stock

Would the factory breather and PCV setup not give enough pathway for crankcase venting on a motor like mine? (440 Six-Pack, Lunati 702 cam, .30 over, stock 915 heads)

[jhaag]

Grec, I would absolutely run a pcv and breather on your engine. What was the reasoning for not doing this? You see the results. Oil everywhere and noxious fumes. Hook it up. You will be glad you did.

[RzeroB]

I used a tee system where the PCV valve contolled the pressure at low RPM & the header evac took over with rpm  this engine never had an issue raced for 9 seasons shifting 7000-7200 + thousands of miles of street driving

I have used one or the other but never both of them combined like this. Sounds simple but I'm not sure how it would be plumbed? Got a diagram or a more detailed description to help me visualize it? Thanks