Help exhaust backfire at hot idle

[Joe66satellite]

1966 satellite 78 440 fresh 30 over forged crank aluminum heads Comp Cams XE 284 / 292 cam Edelbrock RPM intake Edelbrock 750 carburetor number 1407 full MSD ignition p.m. 6425 Doug's 2-inch headers 3in exhaust with h pipe timing now at 11 degrees initial, engine is said to have 11 to 1 compression included is a pic of the cam specs

 

[Joe66satellite]

That is PN 6425 for the MSD box

 

[69L48Z27]

Could be mutilple things. If it’s a full blown back fire it’s loading up and if it’s a pop it’s lean, just for starters.

Pull the plugs and see if it’s lean or fat, or maybe just right.

Try recording a video and post it here.

 

[Joe66satellite]

Could be mutilple things. If it’s a full blown back fire it’s loading up and if it’s a pop it’s lean, just for starters.

Pull the plugs and see if it’s lean or fat, or maybe just right.

Try recording a video and post it here.

Thank you that's where I'm at right now going to pull the plugs and have a look at them and yes I'm sure posting a video is a great idea I'll try and get around to that