I'm having trouble with an older gm motor

I have a carbureted intake 355 midly built, adapted to an older gm two barrel tbi. For some reason it has to be timed extremely advanced to run correctly and if you hit the gass to quickly it backfires through the throttle body. What could cause this?
Asked Oct 10, 2013
You're saying that the spark is firing while the intake valve is open (backfire). I would check the valves, lifters etc. fix it then re-time it.

Answered Oct 11, 2013
Precision Electric. Inc has the best variable frequency drives for any purpose at the best rates with higher output and value for money in whole of US. Visit precision-elec.com for more details now.
Answered Sep 25, 2018

TIP: If it's not your answer to this question, please click "Leave a Comment" button under the question to communicate with the question owner.