[patrickt]

The problem is one of the following:

1) There is a clog in the signal tap that comes off the primary venturi and connects over to the secondary venturi and both connect to the diaphragm housing;

2) There is a leak at the point where the vacuum signal tap goes in to the diaphragm housing, like maybe the little cork gasket;

3) There is a leak in the diaphragm in the housing;

4) There is a jam of some sort in the diaphragm;

5) The linkage on the driver's side is jamming up and preventing the full opening up of the secondaries;

6) The linkage directly below the diaphragm housing is jammed up or the secondary throttle shaft is somehow jammed up.

Let's test for a vacuum leak first. Borrow an extra hand from somebody and then you can wire your primary all the way open, then have your friend push the bottom of the secondary plunger up in the housing and thereby opening the secondaries, then you place one index finger over the signal tap hole in the primary side and the other index finger over the signal tap hole on the secondary side, then tell your friend to release the plunger. If the plunger doesn't stay put while you keep your fingers in place then you have a leak.