Having a TON of carb issues lately. Originally had the Carter AVS and decided I wanted to get some more power out of the car. Went to a pro-systems duel feed double pumper 4150 750 CFM. Changed out the fuel pump for better fuel PSI, and tried to run this carb. The carb was nothing but problems, the car would lean backfire and any work done to the system was tough. It was a mechanical secondary carb, and we changed IAB, power valves you name it and still had lean backfire when we hit the secondaries. Talked to a technician who stated that the car may be too heavy for a mechanical secondary carb and recommended a quick fuel carb.
Cut to ordering a Quick Fuel SS 680 vacuum secondary carb. The decision was made based on talking to reps at Holley, quick fuel and a couple other guys. Running an electric choke on this carb. The car starts up and idles beautifully. The car moves forward off clutch in 1rst gear with no hesitation and is very smooth. The car runs great right up until i hit the secondaries. Then AGAIN I am having the car lean backfire back through the carb. Changed the 6.5 power valve out for an 8.5, but this carb has power valve restrictors at #49. The car definitely is backfiring through the carb and not the exhaust, car doesnt let me operate the secondaries at all in 3rd or 4th gear. Turning the car off it diesels.
Timing right now is 20 degrees initial timing and all in at 3000 RPM is 34 degrees. Running stock jets and only change was to the power valve. Ordered a kit to changed out the flow restrictors from the power valve. Trying to get into a dyno shop that tunes carbs but VERY scarce here in CT. Running manifold vacuum at 12 inches.
Carb Specs:
High Speed Air Bleed 28
Idle Air Bleed Size 70
Material Aluminum
Model SS-Series
Primary Main Jet 68
Primary Power Valve 65
Primary Pump Nozzle Size 31
Secondaries Vacuum
Secondary Main Jet 78
Throttle Bore 1-11/16 inch
Running 85 power valve with 49 restrictors
Running Manifold Vacuum at 12 inches
Timing again is 20 intial, 34 degress all in at 3000
Cut to ordering a Quick Fuel SS 680 vacuum secondary carb. The decision was made based on talking to reps at Holley, quick fuel and a couple other guys. Running an electric choke on this carb. The car starts up and idles beautifully. The car moves forward off clutch in 1rst gear with no hesitation and is very smooth. The car runs great right up until i hit the secondaries. Then AGAIN I am having the car lean backfire back through the carb. Changed the 6.5 power valve out for an 8.5, but this carb has power valve restrictors at #49. The car definitely is backfiring through the carb and not the exhaust, car doesnt let me operate the secondaries at all in 3rd or 4th gear. Turning the car off it diesels.
Timing right now is 20 degrees initial timing and all in at 3000 RPM is 34 degrees. Running stock jets and only change was to the power valve. Ordered a kit to changed out the flow restrictors from the power valve. Trying to get into a dyno shop that tunes carbs but VERY scarce here in CT. Running manifold vacuum at 12 inches.
Carb Specs:
High Speed Air Bleed 28
Idle Air Bleed Size 70
Material Aluminum
Model SS-Series
Primary Main Jet 68
Primary Power Valve 65
Primary Pump Nozzle Size 31
Secondaries Vacuum
Secondary Main Jet 78
Throttle Bore 1-11/16 inch
Running 85 power valve with 49 restrictors
Running Manifold Vacuum at 12 inches
Timing again is 20 intial, 34 degress all in at 3000