I purchased a 56 TBird 312 Fordomatic transmission last fall that needed work. Loadamatic distributor vacuum advance leaked in both diaphragms, Holley 4000 carburetor secondaries not working and numerous vacuum leaks.  Completely rebuilt engine, carburetor, distributor and a NOS vacuum advance.  Runs excellent now, except the maximum advance I can get is 20 degrees.  Manual suggests it should be 26-28 degrees.  Any thoughts where the problem might be?  I've read several posts that suggest the red check valve ball in the distributor port on the carb is not required in automatics, but not sure if this is related or not.
Thanks, Don

Who rebuilt the DIST and was it calibrated on a DIST MACHINE?

____________________________

I think you can bend the posts that the springs mount to to change the advance. You will want to bend them to make the spring shorter. Or set your initial timing so that the max is correct. That usually makes it idle better anyway.

The distributor was calibrated correctly.  The Loadamatic distributor has no springs so that really doesn't apply.

There's 2 Springs on top of the Breaker Plate???.

  

I think you can bend the posts that the springs mount to to change the advance.

If you bend them you will need a new breaker plate.

____________________________

The distributor was calibrated correctly.  The Loadamatic distributor has no springs so that really doesn't apply.

OK ...

There's your problem then, the springs are missing.

Please excuse me ...

____________________________

maybe I was thinking of the bendable posts in the mechanical advance distributor. Anyway, the posts are adjustable wth the eccentric.

Back in the day, they used to sell aftermarket springs with various tensions, in case adjusting the eccentrics wasn’t precise enough to fine-tune the curve.  Of course, you are still left with the problem of how to limit total advance if the springs are weak enough to permit a rapid/performance curve. Hot rodding a Loadomatic is a lost art, typically reserved for those  who want to keep everything looking totally stock, but still want to improve performance over factory capability (which is why most just install a later distributor with mechanical advance).  Rebuilders with a SUN machine usually set the max advance at factory spec or less, since damage from lugging the motor is the major concern.

6 VOLTS/POS. GRD. NW INDIANA