>There are, to my limited knowledge, two types of 4 barrels. The
>mechanically operated secondaries, which are activated by external
>levers and slotted plates that open them at a set opening of the
>primaries at a rate set by the geometry of the linkages. These linkages
>are primarily on the left side of the carb.
>The other is a vacuum operated secondary system. On the Holley, (which
>Ford has sometimes used with their label on it), there is a vacuum
>operated diaphragm/draw-bar on the right rear side of the carb. It has
>a large flat top, covering a rubber diaphragm, and has replaceable rate
>control springs, seals, and check valves to open the secondaries when
>the engine air-flow demands require more. These are adjustable through
>Do either of these sound like yours?
Hay Steve I've got the exact same setup and I can't figure out for the life
of me how the secondaries open or if they even work. There's no external
linkage or diaphram of any sort on the carb. Mine has the numbers
(Autolite C7ZF B A7DC) on it but looks like a Holley to me. What Gives?
Armand & Lorie Ritchie