Quote Originally Posted by Walking-Tall View Post
The primary shafts don't come with the ribbon bushings. If I'm working with a carburetor where there's too much clearance between the primary shaft and the base plate bores, sometimes adding some used (or new, if very loose) bushings tightens up the clearance. There are also channeled areas where they can be positioned if needed.

The steady idle vacuum you're getting is good, but the mixture screw position discrepancies indicate something is jacked up in the carburetor. The best example I can give of this phenomena is a Holley 650 double pumper recently refurbished, where upon disassembly one mixture screw was found to be very much so turned out further out than the other... and (lack of) quality control and manufacture of newer stuff is why... the image below is of a traditional Holley idle air:fuel discharge hole (controlled upstream by the mixture screw in the metering block) that was never fully drilled through, leaving only an 0.018" passage for idle air:fuel to get through:



... where the idle vacuum was pulling idle air:fuel properly through the other, this one had no chance in hell supplying enough, and it's mixture screw was turned out much more than the other... and I guarantee it could not have idled worth a darn from day 1... after that was remedied, the passage hole drilled fully through, everything worked like it should... the mixture screws are equally sensitive and adjusted outward the same amount of turns for best idle.
Thanks; that will give me something to look for.