Hi,
I have a 350 bored 0.030 over and stock heads a high performance cam and no stroke. Probably around 300 HP overall. Autotrans. The engine is a step or two above stock but has the anceint and tiny and restricting stock exhaust manifolds and pipes from 1972. And when I put my engine at proper timing (8* BTDC @ 600 RPM) I get Valve chattering at high RPM. If I retard the timming and.or use higher octane fuel this noise seems to go away. But I am not an expert mechannic. So i do not know for sure if it is vavle chatter, and am not sure exactly what valve chatter is. I also wonder if my extreme back pressure from the exhaust could be a cause. If anyone could help shed some light on this dark dilema I would appreciate it, thanx in advance.

Hi, try a colder heat range spark plug . good luck

cool, (Name ?)
The noise you are describing "sounds" like detonation and is very destructive to an engine if allowed to continue. There are many many causes of detonation, and to be honest with you, to a "non mechanic" it can be very difficult to pinpoint and cure. Anything from incorrect ignition curve to fuel mixture, wrong camshaft etc etc etc. Judging from the sound of your experience level, it might be better to find a good local shop that has experience in tuning older cars, and have them try to figure out what is wrong.