[Guest]

When I downshift and comp brake my engine backfires out the pipes and a 10 inch flame comes out. I have and edelbrock 750 with out of the box setting with the screws two turns out. Thanx

 

[Teebone]

Flames?...cool reminds me of my old racing days..you are running to rich..unburned fuel is igniting in the mufflers..lean it out a bit and also check the timing..

 

[sharkmouth]

Dude if you have an even remotely streetable 351, that 750 is waaaaaaayyyy too big!!

 

[Art]

Try this;
Advance your timing a few degrees..

 

[Guest]

Its on my 390 with a solid cam with .571 lift and 236 degrees of duration so It is a bigger cam. Thanx

 

[CAponyboy]

Hey!!! sounds like you have an afterburner!!!!