440 six pack high idle

Okay folks, here’s where I open it up for all to say, “I told you so!”

While I was able to get the RPMs down by adjusting the timing and linkage, I finally removed the rear outboard to have a look at the throttle plates. The gasket wasn't hanging up at all, but the plates seemed to be hanging open just about .010" or so. Just BARELY enough to be able to see light shining through. I gave a good cleaning with carb cleaner and exercised the shaft quite a few times, also while adding more carb cleaner. The shaft seemed a little gummed up, so my thinking was after a thorough cleaning, a tiny dab of lube where it entered the carb body would help.

I reinstalled the carb and adjusted the linkage and got the engine up to operating temperature, then took it for a test drive around the neighborhood. Idled nicely driving around 15-20 MPH, no big pulls on the throttle though. Upon pulling it into the driveway and placing it in park, no high idle! This was where it was the worst, and it passed the test. Shut the engine off, and NO DIESELING!!

So, while there still may be some small issues to work around, I appreciate the help solving this one.