Exhaust Pops Sound Like Gunshots

[R/T 71]

I just successfully broke in my newly rebuild 340, and it sounded great. After a few days of other tasks, I restarted it and got random, very loud exhaust pops from the right side. Alarming! Those "pops" disappear with increased rpm, but come back at idle. It is idling nicely other than those very alarming explosions. I did change the carburetor from a 750 QFR to an Edelbrock 600 cfm. No apparent vacuum leaks, timing is set at 18* advanced, and all plug wires are secure. Any ideas why this is happening?

 

[Challenger RTA]

Run briefly when doing this.Check disturber cap,plugs and wires.Firing order? Happened to the best of us! move wires to another cylinder,see if it moves. Try to see if you can narrow it down to what cylinder or cylinders.Pull valve cover turn over with stater but not starting. See if a valve is hanging up.

 

[R/T 71]

Thanks Challenger RTA. Always check the simplest things first. I now have the best running 340 in the county, and all I had to do is switch 6 and 8 to their proper orientation. Amazing what the correct firing order will do for an engine.

 

[Challenger RTA]

Been there done that!

 

[BriceRoad]

Me too. One time many years ago I had 5 and 7 mixed up. Glad you got it resolved.

 

[rklein71]

I once helped a friend with his plug wires for his brand X Ford small block. Always had a Mopar, anyhow, Ford engine cylinders are numbered differently than Mopars. Funny thing, didn't want to run, wonder why?