Holley carb

The secondary vacuum diaphragm is sticking when given gas. It doesn't do it when the motor isn't running. This is what I've done. Rebuilt carb (Done this many times on this and my mustang). Tried a different vacuum unit from another Holley. The spring and check ball are in their proper place. With the engine running, if I manually push up on the push rod it will stick. I don't think it can be linkage because it doesn't do it when not running. Or am I wrong? It seems to be a vacuum or it's not bleeding off correctly. Any ideas?

YES! You most likely have the secondaries adjusted too far closed. There is a small adjustment screw on the bottom of the baseplate that if adjusted so that the secondaries do not close so tightly, will most likely solve the problem. Remember though do not adjust this more open than just enough so that it does not stick. Any more and you will mess with the idle circuit. Cheers! Please post a follow up.

I'm familiar with that screw but it was never turned. Are you saying if the main butterflies are open too much, the secondary ones will open?

any other ideas?

This will also happen if the throttle shaft is forced off center, causing the butterflies to hang up in the throttle bores.

I'm familiar with that screw but it was never turned. Are you saying if the main butterflies are open too much, the secondary ones will open?
No he's saying if the butterflies are allowed to shut to far this will happen which may require turning the screw in a little.

The screw that is being talked about is on the secondary butterflies. You need to pull the carb to get at it. You don't want the butterflies closed against the bore. There needs to be a slight clearance. If I'm not mistaken, shouldn't the link on the throttle open the secondary some when moved to wot?

I'll check what you are saying. thanks for the help.

Okay, I adjusted the screw and still has a problem. It does it even if the vacuum rod is disconnected. If I just open the butterflies a little they stick but open up all the way and there fine.

Okay, I adjusted the screw and still has a problem. It does it even if the vacuum rod is disconnected. If I just open the butterflies a little they stick but open up all the way and there fine.
Might have too stiff of a spring in the vacuum actuator. Try changing the spring to one that's not so stiff.

Remove the check ball and try it again. The vacuum can is holding air and keeping it open. I have ran 3310 and 1850 holleys without the check ball and never had a problem. kwik check on if it is the check ball is remove carb hit the throttle linkage to wot and if it sticks turn it upside down to unseat the ball. If it then closes you found the problem. Then go back to remove the check ball.

It can't be the vacuum actuator because it does it with it disconnected.

Are the secondary butterflies hanging open or closed?

If you have nothing attached to the throttle shaft and it still sticks, I'd say you have a bind in the shaft where it goes through the throttle body. Or the throttle blade is a little off and it's sticking on the side of the bore when closed.

Oky reread the posts and realize it's hanging open. Check the small piece of linkage on the accelerator cable side of the carb, has it been played with or bent, did somebody put a screw in the secondary side were that linkage slides? If thats all good you probablely have a hang-up problem on the throttle body bores where the shaft goes thru. And one more thought does it have the mechanical choke and if so is that closing all the way?

Okay, I found the problem. When I got the rebuild kit it had a different base gasket and not thinking I used that one. The difference was the old one had 4 round holes and the new one had one big square hole. Changed gaskets and no more problem. Thanks to everyone trying to help me. Another lesson learned