Engine Timing

Simple 350 Chevy. No big cam or nothing. Mild engine. It likes to run at 4 degrees BTDC opposed to 8-14 degrees like most engines I have had. When I bump it up to 8 degrees it pops and backfires thru the carb.

Just wondering why AND if it will be fine to just leave it at 4 degrees. Runs good and not hot or anything.

Thanks,

Deos it have the right timing tabs on it? Chevy makes 2 different chain covers i think, and the timing tab is different.Just a thought.