ok so , my 86 motor was lopey as hell, dying, massive los of power, acted like it was seriously off timing even though it wasnt, so i scrapped the car 2 years ago, finally got around to taking the heads of --LB9-- and noticed a seriously build up on one single exhaust valve. what can cause this? the valve looked to be seated nicely.

 

Poor oil control on that cylinder (bad rings or valve seals) would cause that.

It could also be caused by a dead cylinder. The gas would only ignite when it the exhaust valve open and exposed it to the well over 1000* exhaust stream, and crap up the valve.

 

Yeah, if there's little or no combustion going on in that cylinder the exhaust valve will crud up, since it doesn't get hot enough to burn the stuff off without red-hot exhaust gasses passing over it. Could be just a dead plug or wire on that cylinder or could be you had the exhaust valve hanging open lightly on that cylinder from mis-adjustment or something more serious.

 

so could the head be bad, or more likely that the rings/piston is dead....?...either way im going to have a machine shop look them over before i stick these on the l03, everyone says these heads are better, so im going to try my hand at gasket matching and bowl polishing...not too sure about anything else, seems like i could do some serious damage if im npot very careful