Having issues, need advice. History. Have this 1978 ranchero it has a factory equipt 351 windsor, recently swapped out the old cast iron 2 barrel intake with a aluminum edlebrock performer, a holly 650 carb, all emissions / smog pump removed, and hooker super competition headers installed have had issues with it overheating so I replaced 180 thermostat with 160. Seems to be going better now. Has horrendous backfire on acceleration, wondering if that could be timing. In hindsight seems like timing should have been checked after 4 barrel swap. What say ye?