BruceB Posted October 6, 2013 Report Share Posted October 6, 2013 Hello everyone. I was wondering if I could get some input from you all? I am having carburetor problems with my '41 Plymouth P12. The engine seems to run fine under a load (though there is an occasional hesitation if I accelerate suddenly), but stalls whenever I disengage the clutch to come to a stop, and just wont idle for any length of time when I start it up. I have been using the throttle control to give her some extra gas to keep her going, but even that doesn't always work. The car does start up ok. The carburetor has been cleaned and new needle valve put in it. Any thoughts? Bruce More info on this--just went out and started her up. As usual this involves using throttle and choke. I found that when the engine warms up, I can close down the throttle and push in the choke almost all way, but if I push it in the last little bit (1/4 inch or so) she dies. I also found that when she is idling with the choke out a bit like that, I can goose the gas peddle and engine will accelerate smoothly, but when I let off the gas, she stalls. It would be nice if there was a place to post videos on this forum so I could SHOW you all what I mean.Bruce Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted October 6, 2013 Report Share Posted October 6, 2013 Have you adjusted your idle mixture needle valve? Have you adjusted your throttle stop screw? Did you soak the accelerator pump leather in oil prior to installing it? Quote Link to comment Share on other sites More sharing options...
Dave72dt Posted October 6, 2013 Report Share Posted October 6, 2013 check for vacuum leaks at the base of the carb, throttle shaft and intake Quote Link to comment Share on other sites More sharing options...
_shel_ny Posted October 6, 2013 Report Share Posted October 6, 2013 Has the carb been off? Will the incorrect/improperly installed carb to manifold gasket cause this? Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted October 6, 2013 Report Share Posted October 6, 2013 (edited) check to see if the idle orifice tube is clear and the discharge jets are also not blocked..there is one above and one below the throttle plate...the fact it runs says the main jet is flowing fuel.. the needle and seat only allow fuel into the carb as checked by the float level...the stumbling car be a bad accelerator pump as Don pointed out and can be serviced at this time by soaking in oil a bit as it is a leather device but it can also be related to the two above mentioned jets as they allow enrichment also during transition to the main jet mixture and will continue to provide some fuel throughout the rpm range do not use wire or other metal devices to clean these hets..they are integral to the throttle body and are preset drill size from the factory Edited October 6, 2013 by Plymouthy Adams Quote Link to comment Share on other sites More sharing options...
greg g Posted October 6, 2013 Report Share Posted October 6, 2013 (edited) Do you have a vacuum gauge? If so attach it to the manifold at the feed for the wiper motor. I would bet that it will show you low vacuum. Stock vacuum at idle should show 18 to 21 inches of vacuum. Less than that suggests there is a leak between the carb and the engine block where the intake manifold mounts. Any air leak after the carb will cause a lean mixture. Lean mixtures are not conducive to proper idling. You can use wd 40, an unlit propane torch, sprayed or passed near the mating surfaces. If the idle smooths or gets faster this indicates where the vacuum leak is. Might even be the vacuum hose to the wiper motor is dried and cracked and letting air in. Edited October 6, 2013 by greg g 1 Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted October 6, 2013 Report Share Posted October 6, 2013 (edited) Do you have a vacuum gauge? If so attach it to the manifold at the feed for the wiper motor. I would bet that it will show you low vacuum. Stock vacuum at idle should show 18 to 21 inches of vacuum. Less than that suggests there is a leak between the carb and the engine block where the intake manifold mounts. Any air leak after the carb will cause a lean mixture. Lean mixtures are not conducive to proper idling. You can use wd 40, an unlit propane torch, sprayed or passed near the mating surfaces. If the idle smooths or gets faster this indicates where the vacuum leak is. an excellent take on the problem...do listen to this advice and do the tests.. other area of interest is worn throttle shaft bushings..they diplace the throttle plate and disrupt air flow at the jets/ports Edited October 6, 2013 by Plymouthy Adams Quote Link to comment Share on other sites More sharing options...
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