Okay so iv had my car on the road for about 2 months now. 450 horse sbc with a th350. Its been running 100%. Went to start it the other day and had some raw fuel in the butterflies it ignited and then i had a fire. Put everything out and my carb was basically ruined. (750dp with 85 jets)
Melted my accel. arms and all the vac. hoes etc. I had an 850 sitting on the self so swapped the jets and threw it on. I had to hold it to the floor to get to start and when it did it ran like crap. Backfiring out the exhaust and intake. idle screw was screwed in alot and the butterflies were bascially sitting open for about 10sec before the motor finally caught up and reved. (seams pig rich) But also when i can get it to rev it has a deep drone and drag, almost like running on 7 cyl. The motor before this would rev to 6500-7k and love every minute of it.

I took the carb off and its being rebuilt. My thought is possibly the power valve cause its just dumping fuel but then why would it lean out and backfire through the intake? The motor ran great before this and it really has me stumped. I leave in 16 days for the military and wanted some more seat time before i put her away. Any thoughts?

 

Did you lose a vacuum hose, particularly one on the intake runner, in the fire?

I assume you're having somebody who knows what they're doing rebuild the carb. They may be able to provide some insight when they're done.