by jmarkaudio » Mon Nov 13, 2023 5:27 am
.081 is a fine place to start. As far as idle jet and bleed sizes, it really depends on the engine its going on. I had to go to .039 on a 600+ HP Pontiac, same carb on my engine was fine with a .037. Vacuum at idle, timing curve, how the cam pulses, texture in the intake tract... lots of things will affect how the idle circuit needs to be tuned. Lean it until you get a stumble or surge in light throttle positions, give it just enough to run clean. Engine temps need to be consistent, gas has multiple chemicals that evaporate at different temps, pump gas can be really temperamental. Sometimes only a 10 degree change will have an effect. Large swings in ambient temps will change it as well, so you may need to make an idle bleed change from summer to winter.