have tried to put 850 ddp on my 468 3310 runs better but runs out at 5500 i think about 80 jets (running 67snow) and ablock conversion with 82s or 84s in back need your opinions terry

 

Depends on the carb. I could give 5 different 850 list numbers and they'll all be jetted differently from the factory.

Idle mixture screws control how the engine runs at idle. Jets allow fuel through the boosters during normal operation. Accelerator pumps and cams give the engine an extra shot of fuel to overcome a lean condition when the throttle is opened. There's also air bleed screws which may or may not be changeable but could also be plugged. Are the power valves replaced with plugs or are the power valves blown?

There's more to tuning a carb than knowing the CFM and changing jets.

How old is the carb? Many times someone find a great deal on a used carb however that usually means the carb is worn out and needs to be thrown out or sold for parts only. You're usually better off just spending the extra money on a new carb than trying to make an old one work.

 

power valves are pluged tried it with 80s 84s 31 sq 37 sq would run up 2000 then die to keep it runnin had to fether pedal then back to 2000

 

With plugged power valves, you need to go up 6 jet sizes from stock. For a street car, put the power valves back in. 6.5's should do fine.