I was having a similar problem with my 59 idling in gear while stopped. Choppy almost to the point of stalling out. Determined that the vacuum line that runs to the transmission had been put too far onto the threaded vacuum nipple which is one of the hold downs for the carb. The vacuum line was sucking air around the threads so I recut the hose and only put it on up to where the threads start. I assume that this line pulls a vacuum on the diaphragm mounted on the transmission which during idle would be a high vacuum which somehow partially disengages the transmission thus lowering the drag on the engine.

 

Hey Mark,
Thanks for your reply. My "won't idle right" issues were more complicated I'm sorry to say. First - I found my vacuum advance unit on my Delco distributor was not working correctly, hence I replaced that. Then I found my advance springs inside my distributor weren't holding my centrifugal weights back correctly such that the weights were kicking in too soon/ at too low of a RPM. The springs had gotten rusty and weakened over the years. Had a forum member help provide me with a set of stiffer springs that worked great.

I then had the WCFB cleaned and rebuilt which found where a gasket had deteriorated and created an internal vacuum leak. While I was checking the carb and distributor out, I went ahead and replaced the vac diaphragm on the Powerglide as well. No leaks around my rear carb bolt vent glad to say. This was the finishing touches to bringing my '59 out of mothball storage for 20 years. I had this car's cam replaced 28 years ago when I had the engine redone, and the replacement cam is not stock so my engine will never idle like the OEM one at 650/700 rpm. Closer to 900 does ok. All in all, I learned a lot and got a chance to correct several non-stock engine issues I had been planning for a long time.

Your '59 looks very nice as well. Mine is Roman red with white coves as well with a red hard top, red interior, 283 and PG.

Thanks,
Dan

 

I have the same engine and trans. I know what the book says about initial advance but my engine runs butter smooth with initial timing at 12 degrees.