Whats the standard valve clearance like with F4Rs?
Has the head been skimmed or the block? valve on piston contact?
It's a long shot, but if it's not tappets then I'm out of ideas
well according to the owner the car was taken for a test drive buy the potential new owner, who's obviously ragged it, but the car was low on oil (no warning light) then the noise started
the owner has put in 4/5L of new oil in and then it came to me 4 days after having new oil, i drained the "new oil" and it was black
there's no bottom end knock, there's no damage to the cams/rockers etc everything appears fine
i don't know the full history of this car, i do know that during mapping by "the tuning comapny" the original engine dropped a valve and totalled the engine, it has been fully rebuilt with high comp pistons, cams etc etc
if a valve was hitting a piston i doubt it would run