i just put a new 280h comp cam in my vette and springs lifters and gear drive. adjusted the valves to 0 lash plus half a turn as advised by comp cams. during the beak in the headers started glowing, 1000 degres on some pipes, the engine does have a blower on it, but dont think that is relevent as it ran fine before. could the valves be too tight or the timing be off causing this, the temp was alittle high at abiut 215. the engine does not want to idle now. you can rev it up and it is right there, please your advice would be appreciated.  

timing is too retarded; either the valve, ingnition or both... the mixture is still burning when it enters the tubes causing them to get hot quick... i had this to happen on a mid 80's chevy truck that had a computer; it went out and would randomlly retard the timing, when it did it lost all power and the temp would soar(if left long enough the manifolds would glow red)  

thanks, i advanced the ignition timing and problem fixed!