318 backfiring

69KillerFish said

I'm suspecting the timing chain jumped a tooth. Any thoughts?

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When this happens, if the car still runs; it takes a huge amount of throttle to keep it running, sometimes even WOT; AND, the ignition timing is also way out of whack. This is because the cam drives the distributor; if the cam goes out of sync, then so does the ignition timing.
If you put the timing back to normal, it may run a lil better, depending on how far it jumped, but you'll be able to tell that it still ain't right.

If you check the timing chain slack by jockeying the crank balancer back and forth, that may give you an idea of how to proceed.