Backfiring through carb/won’t idle/runs well at higher rpm (new GM crate SP350 w/new Holley 4150). Pls help!

[Rustisbest]

Lol sorry bud, no ill intent there. Edited original post to update it correctly.

Have seen many people think it's a timing issue when it's air/fuel related and vice versa. Seen many people try to adjust afr when it's been running for like 3 or 4 mins from a cold start, definitely not even remotely close to even opening the thermostat.

Had an issue with my 4160 Holley where it was doing the same thing. Off idle stumble and would diesel when shutting off after it was at temp. Timing was out by a degree and a half or so, bumped it up to 8° btdc from 9-10ish and it resolved the issue.

Hopefully OP can get that baby running great

Its all good, just giving you a hard time

 

[BlazerBill]

Thank you, everyone for all the great advice. I’ll post updates as I continue to follow all the steps.