Well I lost my #1 cylinder a little while back so I unplugged the spark plug wire so it wouldn't fire, the exhaust valve was not opening and the exhaust gasses were backfiring up through the carb...

Well I thought the lifter had messed itself up so I pulled the intake and valve covers today and bought a full set of lifters, I thought it would be better to replace them all. When I pulled the exhaust valve lifter for the #1 cylinder I didn't look at it too closely and put the new lifter in. I turned the motor over by hand and the valve was still not opening... it was stationary... I took a closer look at the old lifter I pulled out and it shocked me. The bottom of it (towards the cam) was worn like a bowl from the cam lobe, so deep there was a hole in the bottom of the lifter...

I am able to slightly compress the intake #1 valve spring by putting enough force on it, but the exhaust valve spring is solid, can't move it at all...

So... what the hell could have caused this? Why would that valve be stuck? I really don't want to pull the heads or anything but I am fearing I will have to. Do you think the cam lobe is wiped? I'm betting it is pretty well worn considering it tore the heck out of the bottom of that lifter.

Please help! The motor is all stock other than the intake and carb and this is the first time it has really been taken apart this far...