I don't know but the secondaries are closed until the mechanical linkage kicks them in. You should have an extra spring pulling the secondaries back to hold them closed if you do not have vacuum hooked up to the secondaries.it makes the gas pedal kind of stiff but you know when you are kicking it. If you drive the car, I would adjust the mechanical linkage not to kick in until your cruising speed is over about 70-75 mph. That will be turning over 3500 rpms if you have a 4.10. The pumps on the secondaries are probably not kicking in until after your center carb has kicked in. If the secondaries are adjusted too
tight, it could be dumping too much too soon? If they are adjusted not to kick in too soon, you may need more of a shot in the center carb? Do you drag race it?