richards47deluxe Posted May 15, 2011 Report Share Posted May 15, 2011 After changing the vacuum on the carb, for now it responds great, i took my 1947 Plymouth for a ride. runs great but it seems to be geared real low. at about 40 mph the engine revs high, like i should shift into another gear. Solution or ideas? thanks Quote Link to comment Share on other sites More sharing options...
Alshere59 Posted May 15, 2011 Report Share Posted May 15, 2011 From what I know they all run a fairly high RPM. I see you joined in 2007 so is this a new development? Have you driven it a lot or just get it running. It may be a slipping clutch. If you just got it running and the engine seems to be running higher RPM than you like you have a few options. You can change out the rear end for a better gear ratio or add an overdrive tranny or T5. All of this information is on the forum which you probably already know. Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted May 15, 2011 Report Share Posted May 15, 2011 going from a 3.9 to a 3.54 if you could find one is effectively an egiht mile an hour increase in effective cruise speed...for real the true reduction lies in the application of a good OD tranny.. Quote Link to comment Share on other sites More sharing options...
richards47deluxe Posted May 15, 2011 Author Report Share Posted May 15, 2011 joined in 07 when i bought my coupe which is still work in progress and not running. bought the sedan in august for parts but decided to roll it since it is all complete. had it running the next day and been doing things to get it running right. had to replace the head which was wrong for the engine, complete brake job, interior done but not installed. carb just right now after replacing vacuum advance. sittin on a milk crate took it to fuel up and thus my inquiry......... Quote Link to comment Share on other sites More sharing options...
Merle Coggins Posted May 16, 2011 Report Share Posted May 16, 2011 They will run at higher RPM than what you are used to on modern vehicles. Most modern vehicles are built to run around 2000 RPM at highway speeds. These older vehicles would run happily at around 3000 - 3500. It also will sound noisy due to the fixed fan. The fan will make more noise than the engine. If you know what rear gear ratio you have you can calculate the RPM of your engine at a given speed. There are several calculators out on the web, including Tod Fitch's. http://www.ply33.com/Misc/speed Merle Quote Link to comment Share on other sites More sharing options...
richards47deluxe Posted May 17, 2011 Author Report Share Posted May 17, 2011 thanks for your help everyone. i have a tach i will hook up and record the rpms. Quote Link to comment Share on other sites More sharing options...
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