[tekuhn]

Originally Posted by 61-63

FYI as you may know I've done a number of those carbs for people over the years, over ?? eighty sets at this point. For 389 through 535 cubic inch engines using the 2840 carbs you have as well as '59 Buick 2982s as well as 3221 and 3012 Chevy 348 carbs and one set using 2955 Crusader marine carbs. On the vast majority of these sets I installed the secondary air valves that originally came with the carbs back in both carbs. On a few sets I installed a lighter (in weight) valve in the front carb, under the theory that it would observe a weaker signal when it began to open than did the primary carb which opened up first. Most of the 3221 and 3012 (and the 2955s) had the same valves as do the 3010, 3266, and 3433 and 3435 SD carbs which by the way have the same weight valves in both carbs. I have NEVER gotten a comment from any customer re problems with valves opening up as they stabbed the gas pedals. Most of the sets I've done are on show or cruise in cars but at least four sets are on Nostalgia Super Stock cars and no comments from them either. More than one of the 389 engine owners I did the above sets for told me they could get rubber in third gear with their new dual quad setup and they were never able to do this with the tripower set they had before they installed the dual quads. My recommendation to you would thus be to put the original secondary valves back in both carbs and see what happens. If you see a bog, not a hesitation but a kind of ?? dull momentary pause where the engine seems to dag on at one rpm before going on up higher, then take the front valve out and drill a hole at the front edge of both weights and try again and see what happens.

Great information. Thanks, John!