HIF issues

[wicklowwanderer]

Hello!
I have converted my '77 B to HIF's and points distibutor. The carbs had been rebuilt in the past and shelved. I refreshed them with a few new gaskets/seals, check float level, etc. and new throttle shafts with solid throttle plates from Joe. I've done this rebuild in the past with no problems.

The issues are:
Backfiring through front carb and acts like it's starving for fuel on acceleration, rough idle.

I have verified dwell and timing (10 BTC).

Any ideas would be most appreciated!
David

[volksnut]

sounds to me carbs are not in sync or it's possible that carb mixture is lean