my 65 pan is puking approx. 1 qt of 70 wt out the crankcase breather tube an hour at highway speeds. Suspecting blow by i have normal and equal compression in both cyls. and the valves/guides also test ok. The breather has not been retimed and it has about 60 k on it and the problem popped up about 2k after a quick upper end freshening (rings and leaking base gaskets, which were the reason I took it down in the first place)
I took it down again and i cant find anything. WHAT THE HECK?

 

did you go into the breather valve and see if some debris went into it and scored the hole for the valve ????

i think we are talking about a pan BUT you did not say if so what pan up to 64 with a total loss system -- or the only return oiling system 1965 ?????l

 

How about a sheared key inside the oil pump ?

 

Any chance a piece of the gasket got stuck in some part of the oil pump? How about check ball sticking or weak spring?

I would pull cam cover and make sure it is clean of any debris. Also pull pump body from cases and blow air through the holes. At the same time just check to make sure the timing marks are all aligned.

Need to go to the last thing you did. Wasn't occurring before the teardown but it is now.