Tuning Street Demon carb

12many said

MopaR&D, I had to re-read some of your posts to find out exactly what the issue is. Am I correct concluding that you are tuning for a certain AFR reading, vs jetting for maximum WOT power? You mentioned the carb was performing great. While all combos will be different, I found mine to run best with about 12.7 AFR After much testing and tuning at the dragstrip. I take it you don’t have the tuning manual or the specific jetting kit for the carb correct?

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I'm tuning for around the AFR reading that gave me max power when I lived in CO. I do have the manual and the jetting kit for the carb, it's just a funky hybrid design that uses proprietary jets and metering rods on the primary side but the secondary jets are the same as a conventional Holley-style carb. Funny thing is out in CO with the power loss from thinner air and taller gearing at the time I could go WOT long enough on the street to get a seat-of-pants feel of power loss and gain. Here at sea level with shorter gearing I can't floor it more than a few seconds before I'm going too fast and need to hit the brakes so it's hard to tell any minute changes in power lol. 1st gear just spins the tires even from a roll.

This engine combo is also not very sensitive to tuning changes overall which I'm guessing is due to the low (9:1) static compression combined with heavily ported aluminum heads and 222* @ .050" on 110 LSA, .550" lift hydraulic roller cam.