1949-1953 Loadamatic Distributor

[BUBBAS IGNITION]

We dont do a lot of stock loadamatics but for some reason i have done three this week for flathead customers etc. After shipping over 750 of our Chevrolet mechanical advance units i guess we become pretty one sided?
But i feel as if this orginal vacuum only unit is still very much understood so heres some verbage for discussion and a few pictures of the rebuild done this morning......

Motors manual calls this unit a " Holley Full Vacuum type " unit as it only has vacuum advance with No centrifical advance at all .
This vacuum advance is regulated entirely by the vacuum differential at the carburetor. Some call this venturi as the vacuum is developed when the throttle is opened and air flows thru the carb venturis. At idle this signal would be zero and wide open throttle it may reach 3-4 inches of vacuum ( pretty low strength signal).
The actual specs for the unit is 1 degree of engine timing at .30 ( 1/3 or one inch ) of vacuum and 22 degrees of engine timing at 3.7-4 inches of vacuum.
The slightest variation of the throttle plate will cause this signal to change quite a bit. Even a idle set screw adjustment will change the advance rates for the vacuum diaphram. Ford used this type unit from 1949 untill sometime in the 60s with great sucess as long as the engine was in good shape and properly adjusted..
Tear down is pretty easy , however the drive gear and spacer is a bear to remove as the roll pins are pressed into place!!!!
Once apart and cleaned inspect all parts and reassemble applying lube to all moving parts. Pay attention to the snap ring holding the breaker plate, the rotor retaining clip and bushing conditions.
The springs used for the calibration are mounted on twin adjustable pins. Adjustment is possible by pumping up the vacuum chamber however its pretty hard to adjust with vacuum settings so low...