over speed at idle

[Royce Richmond]

Hi folks, I have a 59 coupe with a wierd problem. At idle it goes about 1500RPM but when taken out of park it almost stumbles to a stall. I have tried adjusting the carb and timing but with no results. i can turn in the mixture screws all the way shut with no effect on RPMs. I have a new carb on order but why does putting it in gear almost stalls it out? Any help is appreciated.

[jtschug]

Back off on the idle set screw to get the RPMS down to 450-500 and add some fuel in the idle mixture screws until it stops stalling when you put it in gear.

[Jimntempe]

Hi folks, I have a 59 coupe with a wierd problem. At idle it goes about 1500RPM but when taken out of park it almost stumbles to a stall. I have tried adjusting the carb and timing but with no results. i can turn in the mixture screws all the way shut with no effect on RPMs. I have a new carb on order but why does putting it in gear almost stalls it out? Any help is appreciated.

Does it have a vacuum emergency brake release? If you have that, when you take it out of part it operates a valve to send vacuum to the release vacuum motor. If that's not connected or the diaphragm leaks it like having a large vacuum leak. It might also be that the valve is leaking badly when it supposed to be closed and that's when you get the leak. IAC, if you have one, find the input vacuum line and cap it to see if that changes anything.

[Alan H. Tast]

Does it have a vacuum emergency brake release? If you have that, when you take it out of part it operates a valve to send vacuum to the release vacuum motor. If that's not connected or the diaphragm leaks it like having a large vacuum leak. It might also be that the valve is leaking badly when it supposed to be closed and that's when you get the leak. IAC, if you have one, find the input vacuum line and cap it to see if that changes anything.

That didn't start until 1964. He has a '59. Vacuum connections for '59 are not as extensive as the '61-'63 and '64-later cars, but it does bring up a good point that checking the vacuum system (wipers & optional windshield washers, brake booster, etc.) for leaks is probably another set of items to track down.