Good addition to the post! Have ya got any pictures of the passages etc to go with this discussion?
Maybe a running engine with a large vacuum gauge hooked to a manifold port and a carb Venturi port . Anyone ?.....?..
Quote:
Originally Posted by rotorwrench
I haven't messed with an 8BA carb for many moons but I have worked on several of the Holley 885 carbs for the Mercury cars. In the early 49 units it was set up for the vacuum advance pretty much like the 8BA carbs were. It was designed to give venturi vacuum from a specific port in one of the venturis plus vacuum from a port lower down by the throttle plate. The internal passage would leak some vacuum from the lower port when the throttle was opened condiderably. In mid 1950 they added a nylon ball in there to act as a check valve and close tha lower throttle port during high openenings of the throttle in order to make the system function more efficiently for wide open throttle and heavy throttle opening. Since Holley made both the carburetor and the distributor, they had a pretty good deal going with FOMoCo for a long time. It functions pretty well for a stock engine but became less efficient when the horse power ratings started to climb with MEL & FE block engines and the Y-blocks changed over to the small block Fords of the 60s. It just didn't do as well with the OHV engines but for flatheads it was adequate.
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