I am trying to get the 216 from hell running properly. I have rebuilt this engine with 60 over bore and pistons, line bored, valve job, rebuilt the Carter YF carb and am still not satisfied at all. It starts and runs and has compression now in the 85 to 100 pounds range on the dry test. all increase with the wet test. engine is still not completely broken in, has just been run in place. Oil pressure and temperature perform well. It starts , runs idles and accelerates well, but does not seem at this point to have the power I expected. Problem is that is backfires when I run it at a higher RPM. Sounds like one cylinder may not be right. It runs at the higher RPM and periodically backfires out the exhaust, and once through the carb. I am also seriously considering dropping the pan and checking the bearing clearances as well. I have a slight knock/noise I don't like too.
Question is what would cause the backfire?
