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I have a 69 Z28 with the original 302 and DZ coded Holley carb. As of last Friday night I learned there are two return springs for the throttle linkage with a smaller spring inside of a larger spring. I've been having problems with the the throttle returning all the way to the stop. A slight touch on the lever by hand will make it return but this is hard to do when sitting in the drivers seat. Anyways it was pointed out that I was missing the inner return spring. I was shown this setup in a 68 Camaro. Did the 69 have this two spring setup? What is the purpose of the two springs? In my case I can see where having the two springs would probably solve my problem. It appears the throttle linkage is binding on the high idle cam slightly. Do I fix this (I'm not sure what to change other than a little filing) or should I just install a second spring and be done with it?
Mark
 

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According to the 69 Camaro assembly manual (page 472) the 302DZ engine had only one return accelerator spring. You didn't say where you have your spring attached. It should be connected to a tab on the plug wire stand. If your is not, then this may be some of the problem. The spring for 1969 is also different than the spring for 1968.
 

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The purpose of the two springs, If one fails there is a back up.
Another thought on the poor return is a worn throttle plate shaft, that is hanging up.
check for any excessive wear on the main throttle shaft by lifting up and down.
Do this while the engine is idling, any great changes in idle speed would confirm.
 

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I have a friend who had the same problem on his street rod. He had the return spring hooked to the throttle arm, but it was too close to the throttle shaft. He had it hooked into the holes near the accelerator pump plastic cam. It needs to be on the lower hole for the auto trans kick down. Not used on a Z/28 of course. Does your carb have this hole? It should be maybe 1 1/2" below the throttle shaft.
David

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The older I get, the faster I was!
 
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