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Discussion Starter #1
Having drivability issues with 69 400/350 4 speed. Between shifts, hits a dead spot before catching and lurching. have found that the base gasket to the Quadrajet is sucking air, maybe part of the problem? But while diagnosing, I cant get the vacuum secondaries to open more than a quarter inch, no matter how much throttle I give it while static. Is this normal, or should they be opening wide? Anyone with advise? thanks
 

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The throttle plate is mechanical so look to see if the gasket is interfering with the throttle plates movement. My '69 Quadrajet has had similar issues and it was related to the position of the base gasket.
 

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Discussion Starter #3
the secondaries are mechanical? There was linkage connecting the primary with secondary, which would not move the secondaries plates. However on the right side of the carb there was a vacuum unit that looked like it may operate them. Should the linkage being be opening them?
 

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They are both mechanical and vacuum. The secondary's on the base plate are mechanically opened (only when the choke is fully open) and allows the intake vacuum to open the upper plates that connect to the secondary jets.
The vacuum unit on the right side is probably the choke pull off which slightly opens the choke plate at start up to prevent it from loading up on fuel.
 

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Make sure the choke safety lever is adjusted properly. The pull off should pull it all the way so that the secondarys can open. It's there to prevent the secondaries from operating when the engine is cold. If out of adjustment, your secondaries will not open.
 
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