[stag]

I have the same problem ! I have a reconditioned Rover V8 . I am using Penrite Running In Oil . After about 20 min.
running the left hand bank rockers rattle badly . It appears that they have been starved of oil . When the motor cools and
I start it up there is no delay in the left bank getting oil as there is no rattle. The right bank Runs perfectly. After 20 min
the left bank rattles again. Someone on this forum suggested the oil was thinning out - any more thoughts would be
appreciated. Incidentally I am in Sydney in the land of OZ

 

[BogiesAnnex1]

Yep flat tappets need a convex face. The lobe has a slight angle. The combination causes the lifter to rotate in its bore. This reduces the rubbing forces and spreads the wear across the lifter foot‘s diameter. This on the Chevy is also used to keep tension on the cam gear thrust surface.

Resurfacing the lifters to a flat surface destroyed both functions. The load between lobe and lifter is now a narrow band on the high side of the lobe, wear rate is way up and thrust tension unstable.

Your going to have to bust out the wrench’s and dive in to see what’s going on.

Worst case the lifters and lobes are going, going and perhaps gone. The chips fell in the oil and circulated.

Bogie

 

[Crosley]

stag: I moved your new question to a new thread. You posted to a 10+ year old thread. thanks

 

[chasracer]

Try two things because you have nothing to lose at this point.

Put a quart of transmission in it and drive it for 20-30 minutes. Change the oil and filter and use a heavier oil - preferably not a multi-grade which is admittedly hard to find but a straight 30 or 40 would be good.

The trans fluid will clear out any oil returns or sticky lifter mess.

The oil change to something heavier might just fill in extra clearances that are causing the noise.

If it doesn't work then it's a definite mechanical issue

 

[johnsongrass1]

I'd cut open the oil filter first, That'll tell you the internal secrets.