[seningen]

Originally Posted by Jake Raby

Either you have a bad "New" AOS (which we see all the time when testing with a Manometer) or the valve stem seals are hardened and allowing oil past them.

This is what happens with the glorious engine oil and service intervals dictated by the factory.

Hardened stem seals allow oil to be sucked past the intake valves during heavy manifold vacuum. Oil that puddles in the cam covers from G force aggregation can also leak past exhaust stem seals and end up in the exhaust system.

Worn valve guides can have a similar impact as the excess movement in the valve impacts the ability of the stem seal to do its job.

Not to question the above which are all good suggestions/observations:

Could Ovality come into play here causing blow by which is overwhelming the AOS?

If so -- what is the easiest way to check?

Mike