[matt406]

iv got a old school 780 holley on it it was back firing through the carb when i would rev it up or when you would be going down the high way giving it gas going through the gears or if you would stomp on it it would pop and it wouldnt go very good so i advanced the timing thinking it was retarded to much but it didnt go away and i replaced the power valve still same thing. i switched carberators to a 600 double pumper just to see if it still did it. it still did. no mater how little or how much timing i give it. it still back fires and doesnt drive good at all but suprizingly it idles pretty good. if i advance to much i pops out the exaust. the engine only has 25 miles on it. it has 550 hp 650 ft of torque.


any help would greatly be appriciated im out of ideas-

[techinspector1]

If you used a flat tappet cam, one or more of the lifters/lobes could be goin' South. Remove the valve covers with the motor idling and observed the rocker arm movement for each valve. If you find one or more that are lazy, the cam is roached and you have shrapnel throughout the motor. Time for a tear-down, good cleaning of all galleys and a rebuild with a roller cam.

[hpete]

I think the first thing I'd look at would be the plug wires, make sure their not crossed and that their well separated. Dizzy cap can cause stuff like this too. Thats a pretty high output 396 I hope your using a light and not guessing at this stuff.

[matt406]

i figured out the problem the brand new distributer was bad. i replaced it with an old one i had and fixed the problem. thank you for the input