Re: timing ?????
You really do not want to retard engine timing on a high compression engine, it could cause a lot of problems to cylinder combustion at high rpms. Normally on high performance (depending on compression ratio, cam specs, carberation, fuel supply etc...) you'll want to advance the timing to 12 BTDC and advance to around 16 at WOT. Our race engine's timing is locked down and we set them at 38, but your also talking 820 HP 18 degree 16.5 to 1 compression with 2.16 intake valves.
What kind of compression and heads? Also if it is popping is it exhaust or carb? Are the valves adjusted correctly? Is it a solid cam, roller, or hydraulic? If you rebuilt the carb you could have been running lean and causing a pop, other then that it's a timing issue. I would set intial timing at 12 and check with engine at 4000 RPM for advance. PLenty of reasons for it to pop, if you have to retard the timing in order for it to quit then you have another issue, valves improperly adjusted, distributor is off, timing chain is off, internal issue with advance on distributor, etc.. you need to go back through everything or you could risk destroying the engine. Also, you never said what kind of engine, ignition, and fuel supply it was. JMO, goodluck
