Hy guys...need your help again.Since im your student and a greenhorn in v8 engines here is my problem.On my 502 cheavy pistons are touching my intake valve...

as you can see...The pistons are H127cp std...heads are 088...intake valve is 55mm...i checked the stroke and it is a bit more then 10 cm...Can you tell me what is the standard valve/piston clearenc in a 502 with these pistons and maybe how to check my cam is it stock or aftermarket.I know im short of imformations but yust to get an idea what to look for..ill check my faze chain today.Could this be because of a wrong valve preload?The head gasket is allso stock felpro..thank you

How long was engine assembled and ran like this?
the valve reliefs in picture should be able to take more lift then most inboard applications would have,
IM gonna go with someone cranked on valve adjustment preload way too much or cam was advanced , way advanced but again, if it ran for 50 or 100 hrs, someone adjusted the valves then this happened, there's your answer. If it ran for 5 minutes, cam timing

Hello profesor nice to see you..Yes the motor ran very short time...i reved it till about 3000 rpm then he burned my spark plug on that cilindar(number 6)...so it could be the preload..ok. Can you tell me a simple way how to know what cam do i have...I've seen video where i need to put 1 cil in tdc then look at lifters at cil 6 and if they stick aut of the block the same hight i have stock cam..Em i right?

Sticking valve maybe
Rockers are torqued to 40 lb ft
Look at the rear end of the cam for numbers

The cam is in side of the engine can't see numbers...Do you know what should be valve/piston gap on this engine?

Don't know off hand, but if the clearance was to close then all valves would be hitting.
Burning a plug or piston is most often caused by a lean condition (not enough fuel) and pre-ignition
To set timing the crank and cam gears are aligned and bringing No 1 to TDC is for installing the distributor

I would not go closer than .100.

That's 0.100 inc?I'm from europa have to recalculate...(2.5mm)..Ok thank you wery much..Do you maybe know how to check my cam if it is stock?

Last several times we have seen this on oso is people using timing chain gears with multiple keyways and both times they installed them wrong.

edit in: they bent some valves too. I’m assuming you bent some OP ?

Ooo man profesor SB so good to here from you..Can you simplify ( multiple keyways) dont understand...And yes my intake valve bent on cil 6 that is the one that melted my spark plug..