Just to make sure I'm not confusing everyone, I'm working on a Edelbrock/Weber 1406 600 cfm. Both the old and the new cups are rubber. The distance from the "flange" on the stem to the s-hook hole on both is the same but the length from the flange to the cup is at least a 1/4" more on the new plunger. The spring is also much heavier. I think it's more than can be compensated for with the linkage. It seems like the new one is wrong but maybe I'm misunderstanding how it operates.