I decided to tear into my problem head[/SIZE]. I need to change the sbc valves with the oe length ones from SI valves. There is a subtle diesel noise coming from the head. I tried to tighten the rockers a quarter turn, from 1/4 to 1/2 turn, but no change.

When I examine and change the valves, I will most likely change the lifters and cam too, since they were in the original engine, changing to the Isky 262 cam, or the Comp 268.

 

If I remember your article you used new rockers right ? I've seen high mile engines get a little noisy up there, that is the rockers get a little beat and theres a gap between them and the valve. Check your rocker arms underneath to see if they're taking a beating.