I get really close to tuning the carb per the manual. Then after driving a while, when I put it in park the idle goes back up to 1140. It looks to me that the throttle linkage is hanging up after driving for a while. If I push down on the idle adjustment screw, it drops down a bit and levels out. How would I fix this?

 

Make sure it's not hanging on the choke high idle setting, first.

Check your carb with the linkage off and see if it's binding. Make sure any return springs are not causing interference. Make sure the rest of your linkage at the firewall is not binding.

Make sure the return spring on the carb is not broken. I alway like to supplement with an added return spring, not a heavy one to assist the linkage with a positive return.

 

Taking the daughter to college. I'll check when I get back next week. The high idle is not hanging. I am curious as to how you supplement with the additional return spring.

 

They are available at any auto parts store, I use a light weight double spring and the L bracket that comes with the setup.

This what I use

http://www.summitracing.com/parts/MRG-19/

 

how are your motor mounts? the reason i ask is that the throttle rod setup shows this problem much more than the cable setup in later years. you may need to lube your bellcrank assembly. the throttle rod also has adjustment capability.


bill

 

oldcutlass: Finally got the chance to work the throttle issue. I think I got it solved. Linkage was adjusted too short. But, I like the idea of backup return springs. Does the double spring you bought from Summit replace the original, or do you use it as a 2nd and 3rd backup? If so, where did you mount the bracket?

Bill: Thanks for the help. How can you tell if the mount is shot? Not sure I have the lift equipment to hold the motor up while replacing the mounts.

 

The originals are attatched by the firewall on mine, so I use the one I linked to as a supplement.

 

first thing is if your oil pan is resting on the crossmember-lol (ask me how i know).
the second way is a visual inspection-look for dried-out, crusty rubber. the third is a little bit dangerous... have somebody stand on the brakes while you gas it some in drive, then reverse, while you're looking under the hood. if the engine moves more than an inch or so, you'll want to replace the mounts. i had one where the engine would actually lift off the mount.


bill