High RPMs, how to bring it down? ANSWER FOUND

[jaxops]

You may not remember this one.  It took a number of tries and nights thinking about it.  My 1956 Cadillac had its rpms advanced to near 1400 at idle, and I couldn't figure how to bring them down.  Everything was in tune and aligned except the accelerator rod had a shine on the end near the firewall.  I pulled the cotter pin on the accelerator rod on the carburetor and once freed, turn it tighter 3 turns.  I popped it back in with a slight tap of a wrench and tried it.  Voila!  Back to where we needed it in the 750-800 rpms at idle range. 

While I was at it, I did shift the mixture one notch towards "rich" although it is still definitely in the middle, and pulled the air-fuel mix screws out one turn to "4" turns out from dead-ended.  They had been at 3 turns out and I wanted to increase the fuel just a tad.  So far so good.  I am going to go through the "Thoro-Check" procedure and make sure I didn't miss anything. 

You never know what shortcuts some mechanics will take  . 

We spoke in another thread about conclusions never making it back into the forum when a question is asked.

[35-709]

If your RPMs increased caused by the rod accelerator rod needing to be adjusted when no one had messed with it, you might want to check your motor mounts carefully.

[jaxops]

That was the point, it was messed with although I didn't know it.

[wearymicrobe]

On my 57 there is a vacuum activated stopper near the end of the accelerator rod near the firewall that got stuck open and caused a similar issue. There will be a large round headed bolt that hits the vacuum activator. It was supposed to stop the cars from stalling if someone let off the throttle hard. You might want to check this as well to ensure that you don;' have binding.

These will break. Frankly I removed mine as its one less place the vacuum can leak in the car.

[jaxops]

Yes I have that as well.  I was able to bring it down a bit by closing that screw a bit but put it back out after I found the real culprit (the accelerator rod).  At least that kept it under control.  Thanks!