SOLVED! 318 2500-3000 rpm idling issue. Don't think its a regular vacuum leak. Swapped 2 intakes, 2 carbs ,and 6 different gaskets still no luck.

Killer6 said
:rofl:
I was just going to ask if You were using a handheld tune-up tach, or one already in the vehicle, & to check the setting/hookup......some old tachs also have an issue with HEI signals depending on the hookup.

Is it backfiring as in spitting/coughing out the carb, or is it combustion of unburnt/excess fuel in the exhaust pipes......or both?

It did it through the carb once or twice blipping it at first but as I revved it up to 4500rpm and back down a few times it seemed to clear up and stat running better.

Just a standard in car tach on the coils. Now that's it's set right it's reading far far more accurately immediately inclined to believe it.