After taking off the timing chain cover of my 455, noticed two things; one tooth half broken off on camshaft gear; slack in the timing chain itself; can anyone tell me how much slack is tolerable on the chain? whether a half broken off tooth, only one, is acceptable, or should I get new gears? the engine is origional, from a 73 centurion. seems to be alot of slack in the chain, how measure? tx in advance for help John