Rear main seal leak

[DRCBOWTIE]

Maybe someone here can make a suggestion. 72 Z28, original engine, engine was supposed to have been rebuilt about 8 years ago, not much mileage since.

So, rear main seal did not leak when my buddy recently purchased the car. Someone put in a non stock cam so he decided to do the right cam, and had local engine builder do a basic rebuild also; bearings, rings, etc. Result, the rear main started leaking.

This is a trusted local engine builder, and he was surprised to see it leaking. Looks like it was align bored at one point, but engine guy says very little taken out, should not effect rear seal. Did notice some small pitting on the crank journal main, so we bought a new crank, seal, etc. and did it again. Still leaks. Engine guy then does a FelPro offset seal, still leaks, and engine guy is perplexed, feels terrible, just cannot figure why it still leaks.

We just bought a NOS GM rear main seal off of E-Bay, thinking maybe somehow in today's world the FelPro seals are junk like a lot of current aftermarket things. We will have engine guy look at it and give his thoughts on next step, may have to pull the engine again and just tear it down, mic everything and come to some conclusion.

So, any thoughts on this, it really is odd.

Thanks.