Is it possible your 2100S has the wrong base installed? I have 1-788 casting base plates that have different staked on throttle linkage arms. (the 2101S has 1-788 base with a different linkage design) The 2100S base casting for the 235 Chevy engines has the hole the for the linkage sitting at about 4:30 ay idle and 1:30 at wide open. My linkage looks different from your picture. The correct 1-788 base should attach with no alteration to the rod from the engine. Perhaps Carb King will ring in with the answer.
