Why advance timing?

A new (larger) carb will have a different vacuum level on accel/cruise so it will cause the vac. canister to behave differently. You can change it for a canister that is more sensitive. It doesn't matter where the carb came from (Ford, Chev, Mopar) as long as it has a ported vacuum nipple.

A recurved distributor still uses a vacuum advance - all 'recurving' means is modifying the advance curve to optimize spark advance for your engine. You CAN have a distributor recurved to eliminate the vacuum advance but it's not recommended for a street car since vacuum advance is important for fuel economy.

memike said

Mine was not moving after my up dates, must be a low vacuum draw on the 390 4 barrel , because it works pulling a vacuum manually myself, I just don't think I had enough vacuum for it to operate correctly, I believe I am running a ford Carb now, and the vacuum system are not matched anymore . A recurved Distributor does not use vacuum, it reads and advances on it's own, If I had the fists picture set up I had (first picture) the vacuum may have worked but I never checked

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