Okay first thing forget what year my Burban is ( 91' ) and same thing with motor ( 96-98 ) 454 and the fact its carbed no injection.

Its a 454 -400 turbo one ton running gear-and when i picked it up in a trade
someone had spent a lot of money on the drivetrain which is fine and the motor wa clean as well.BUT the put an edelbrock performer intake and a carter hi-volume fuel pup on it,still all good.Then slapped a worn out,leaky pos qjet on it.I found a new Barry grant Speed Demon 750 Vac Sec carb for it.

Piddled with it,went thru put the jets back to stock adjust float levels,set up the electric choke and one pump bam fires right up,low idle speed..adjust the choke idle speed and now she works great,well mostly.

Issue is im on the hiway floor it,feel the secondaries open feels right so far then i hear feel kinda of a small backfire type noise,do a loop again WOT this time pulls like a bear dont hear it or feel it.Now this is not my first dance when i park Chub's i smell the tail pipe and i will be damned it smells a little lean.

Any feedback or thoughts on this would be great.