Jon H, the engine is a new rebuild so timing was never set.
Jon G, I backed the timing down to 8 degrees, It is better but not perfect.
If I drive gently, it behaves and does not act up. If I drive aggressively and floor it, it will spit, sputter, and backfire though the rear carb, never the front carb. Thats the odd thing.
I had it up to 55mph by slowly getting there. I have a Gear Vender Overdrive behind my SM420 and the 4.56:1 rear end ratio. 50mph is about 2000rpm. Final ratio
should be 3.55:1. The truck has plenty of power and water temp steady at 185 degrees, oil pressure at 35lbs. Trany shifts fine and is smooth. The rear end, I put in new wheel seals and pinion seal. Brakes are the Huck brakes, all rebuilt and work well. This is a 47 3600 Chevy.
The air fuel ratio gauge would be the best for tuning, I'm sure. I put EGT on my snowmobile to get the tunning right on, so I know it would be the best way to dial these carbs in.
I think the primary jet is too large because my mixture screw is at 1 turn.
