426 hemi backfires

[money pit]

Hey guys i have a crate 426 hemi in a bird clone, the problem that is going on is the car back fires out the exhaust, now i have the stock ignition that came with it, and a holly 750 per the instructions,3 inch exhaust, tti headers, nothing to fancy, but when i fired it up for the first time this thing ran strong then it went back to the painter/car guy/ mechanic, it won't even hold at idle and it just pops out the exhaust and runs rough. thanks scott

[ChgrSteve67]

I would start with capping the vacuum advance, check to make sure all of the vacuum ports on the carb are plugged then check the timing.

[money pit]

thanks, i will try that and see what happens

[Cooter]

but when i fired it up for the first time this thing ran strong then it went back to the painter/car guy/ mechanic, it won't even hold at idle and it just pops out the exhaust and runs rough.

This happened to a lady here with a VERY low mileage '68 Hemi Charger R/T. She drops off at bodyshop, about three weeks later, it had a rod knock. (Misteriously)....

Look at firing order. Id ok, start pulling plug wires till backfire stops.