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Would like to lean low gear some keeping high gear as is

PostPosted: Tue Aug 01, 2023 11:06 pm
by 2x4b4fun
I should be able to figure this out but after many emulsion changes as to size and position in conjunction with HSBs, jet changes, float level changes, metering blocks with varying internal passage sizes plus banjo's with varying diameters this is about the best result. One good result was eliminating the lean spike on the shift, finally. Leaning pump shot only creates a hesitation going on the brake. I think initial launch and bowl fuel level from low to high gear may be the main culprits but just guessing. Anyone have any ideas or experience for balancing the fuel mixture out? I want to pull low gear mixture up level with high gear without leaning main jetting if possible. The car runs decent and is pretty consistent and only varied 2 numbers in 12 hours from 90 degree temps to high 60's with a major dew fall. Carbs are 2X1050 9375 converted to 2 circuit and E85 on a Dart tunnel ram topping a 632 2800lb car 4.29 gear 106 rollout tires. Jetting is .140, 34* timing. Electric fuel pumps to dead head regulators @ 6psi. This particular run was 1.19 60, 5.26 @ 132mph. In good air & tight track this same setup goes 5.13-14 @ 134mph. Not wanting or needing to go any faster but solving this mixture unbalance would help me with the other conversions I have. Thanks for any ideas', George

Re: Would like to lean low gear some keeping high gear as is

PostPosted: Sun Oct 15, 2023 10:52 pm
by 2x4b4fun
This is a follow up on my question of how to lean low gear without getting the top end too lean. I got closer to my target AFR throughout the run by accident when I changed from a tall visibility blocking scoop to a 2X4 Lexan scoop. My original scoop was sealed off and had 6-7 inches clearance over the carbs and had been on the car for over ten years. I saw no reason for it to be deficient but it was. Changing to a 4" high lexan scoop caused the carbs to richen some so now they are at 102 Holley or .133 jets (9375 1050's on E85 straight banjo's). MPH has picked up to the 135.5 range, 60's have dropped to 1.127-1.132 range and 5.13-14 ET in 85 degree temps. The car has not been run in cooler temps yet but it may pick up another tenth. Being too rich on launch was really limiting the 60 et and low end power. The initial hit is still on the rich side but it picks up quickly halfway through first now keeping lambda in the .83 -.85 range where I wanted it for consistency. Second race with the new scoop got me another win with several dead on passes. Maybe my stumbling on a solution for balancing AFR on a run will help someone else with a similar issue. Geo.