[ceejayjay]

My 454 Chevy has always produced a pleasing belch of flame under hardbacking off of the throttle but now pops a bit more than I would like even under gentle throttle off. No discernible change in running or performance, and my best guess is either a dodgy plug going slowly on the blink or dud wire. The plugs ara a total bastard to get at!!! - need three different bits of cobbled tools to do!! so don't want to go that route if its being caused by something else.
Thoughts?
Carb untouched by human hand and has been dead reliable - holley 750 double pumper.

Thansk
Chris