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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?
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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.
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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?
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This will also happen if the throttle shaft is forced off center, causing the butterflies to hang up in the throttle bores.
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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.
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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?
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I'll check what you are saying. thanks for the help.
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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.
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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.