[ta man]

Originally Posted by Hesster1977

"New engine, no PCV, blowing oil out the rear main like crazy and winter Frothing of oil."

Yep - I suffered with Rear Main leaks on my modded Pontiac 400 block. Especially after upping the horsepower. I tried everything - ditched the Rope Seal and went with Viton, tried various PVC set-up's, Catch Cans, etc.

I don't know what it is with Pontiac Engines making so much Crankcase pressure?

Finally went with a Butler Crankcase Evac Kit - expensive, but it works great. Problem solved.

I think its the rpm's..a factory 455 would maybe see 5200 rpm ...maybe 5500...mine can see 6500..big difference .Engine is an air pump works both ways.

[steve25]

With any aftermarket rear main seal that is not a rope type crankcase pressure helps to load the seal harder to the crank.

It’s part of the seals design.
I saw one fellow mistakenly put the aftermarket seal n the wrong way and after all his effort he ended up with a bigger leak then if he would have left the rope seal in.

Luck the next weekend 3 of us local Pontiac guys where free to help out and in 4 hours the mistake was corrected and the motor was being driven .

[Mr Twister]

I would send a sample of the oil to Blackstone Labs to rule out coolant contamination.