Pumping oil out exhaust

[magoo231]

I have a 1641 in my rail that is pumping oil out the exhaust on the right bank both cylinders. I pulled the head and jugs no cracked pistons or broken rings. I looked at the heads no visibile cracks. But it pumping about a quart a hour out the exhaust pipe. Does any one have any ideas about were to look next?

[mk-Zero]

Oil can get into the combustion chamber two ways: rings and valve guides. Were the rings oriented correctly?

[magoo231]

As far as i noticed when removing the jugs. my brother over reved the engine this is when it started smoking a little 30 min more of driving it started pumping oil out the exhaust .the heads are big valve heads rebuilt at the same time the engine was built no more than 10 hrs on all of it