[C1] 2x4 Musing
Race Director
Joined: Apr 2015
Posts: 17,571
Likes: 3,460
From: Fresno California
That would be my answer, since it's a dual plane intake and the rear carb is the main driving carb. On my tripower Pontiacs with 3 two barrel carbs, only the middle carb has mixture screws and an idle circuit. But it's smack dab in the middle of the intake, not installed at the back like the dual quads.
Race Director
Joined: Mar 2001
Posts: 14,609
Likes: 4,665
From: Mustang OK
2026 Corvette of the Year Finalist - Modified
2025 c1 of the Year - Modified Winner
2024 C1 of the Year Finalist - Modified
2023 C1 of the Year Finalist - Modified
2015 C1 of the Year Finalist
On WCFB 2x4 setups, the front carb is the secondary carb. The throttle valves on the primary side of BOTH carbs is NEVER closed completely. Thus, for idle purposes, there needs to be idle mixture adjustment screws. Per the Carter adjustment instructions, idle mixture and idle speed is specifically defined for tuning both carbs.
