Q: Backfiring from throttle bodies when under load. 1984 Chevrolet Corvette

Hello - backfiring can be caused both by timing issues, as well as air leaks (unmetered air) into the intake. I would first have the timing set to be sure it is correct - since there is some reason to believe it may not be. If you still have backfiring, check for air leaks in the intake (starter fluid or smoke test metod). The Crossfire manifold system is complex enough for any of us to get right! For assistance, I recommend a backfiring inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

Hello - backfiring can be caused both by timing issues, and by a leaking intake (un-metered air getting into the system. I would first get the timing set correctly, since this can be done without taking things back apart, and there is some question as to whether it’s correct now. The Crossfire intake is tricky enough for most any of us to install and seal properly. If you still have backfiring after getting the timing correct, I would test for leaks in the intake system (starter fluid or smoke test techniques). Worst case, remove and re-install the intake manifold to be sure there are no air leaks since this was the last engine maintenance. For assistance, I recommend an engine backfiring inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.