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In this Discussion
- 66patrick66 June 2006
- Ray Bell June 2006
- topsgtsarg July 2006
51 Cambridge Mods
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I picked up my 1951 last week and its in pretty good shape, body, interior and engine. I was able to drive it on the freeway which brings me to the mods I want to do to it. Being a slower I feel the car it dangerous to drive on the freeways when people are passing at 20-30 mph. Is there an overdrive kit that I can put on there without changing the current inline 6 and 3 speed manual? I also want to change it to a 12 volt system. Ive read a little on this already but what Ive been reading is from the Bel airs. Dont know if there are any differences between the cars or not. If I am to keep the original engine, would I be able to use a mid 70s inline 6 HEI distributor to get rid of the points? Also, I would like to convert the brakes to disk. Ive found a site, http://ecihotrodbrakes.com/dodge_plymouth_discbrake_conversions.html and they have them but would I be able to buy parts from the part store to use as the conversion?
Thank you in advance for all the info. This site has already answered many other questions. -
Pertronix offers a 12V electronic ignition conversion kit for the early '50s Mopar distributors. You could take a GM HEI 6-cyl distributor and mate it somehow with the Mopar distributor body and shaft, though obviously there would be a lot of work involved. I think the Pertronix kit would be better in the long run, though.
Dodge and Plymouth offered an overdrive unit on the '50-'52 cars, and should be easy enough to find one. I don't remember if it was integral to the tranny or an add-on unit. My '52 had the 3-speed and no o/d. You might measure the rear axle and swap in a Mopar 8-3/4" or 9-1/4" unit, or a Ford 8" or 9" unit and go with more highway-friendly gears vs. an o/d unit. Don't go too crazy. Stick with a 3.07, 3.23, or 3.31 gear so you'll still have enough power to get out of the way and still keep up with modern traffic."The time has come", the Walrus said, "to speak of many things. Of shoes and ships and sealing wax, of cabbages and kings. And why the sea is boiling hot,
And whether pigs have wings..." -
The overdrive took the place of the extension housing on the gearbox, the ratio is 0.7:1.
With some more modern tyres, and care with your now-inadequate brakes (ie. drive with a view to seeing further ahead), or maybe some bigger or better brakes, there's no reason why you can't cruise at 70mph with the flathead as it is, 80 or more with overdrive installed.
Rear axle ratios were usually about 3.5:1 without overdrive, about 4:1 with overdrive. So overdrive finished up equivalent to about 3.0 or manybe even 2.8:1. -
:confused:blazerswampthing wrote:I picked up my 1951 last week and its in pretty good shape, body, interior and engine. I was able to drive it on the freeway which brings me to the mods I want to do to it. Being a slower I feel the car it dangerous to drive on the freeways when people are passing at 20-30 mph. Is there an overdrive kit that I can put on there without changing the current inline 6 and 3 speed manual? I also want to change it to a 12 volt system. Ive read a little on this already but what Ive been reading is from the Bel airs. Dont know if there are any differences between the cars or not. If I am to keep the original engine, would I be able to use a mid 70s inline 6 HEI distributor to get rid of the points? Also, I would like to convert the brakes to disk. Ive found a site, http://ecihotrodbrakes.com/dodge_plymouth_discbrake_conversions.html and they have them but would I be able to buy parts from the part store to use as the conversion?
Thank you in advance for all the info. This site has already answered many other questions.
My Grand Father was The Master Mechanic at the Tulsa, OK Chrysler-Plymouth-Dodge dealer from the 30's to 1979. He had retired 4 years before that but they asked him to be a 'consultant' for those cars that none of the young mechanics could figure out how to fix what was wrong.
He was down there every day. He could dianose those alternators and repair them faster than they could. Same with any of the electrical problems.
He had a 1951 Plymouth 4 door w/o OD and determined that the best speed for the car was 55 MPH. That returned the best gas milage. But there were NO freeways between El Dorado, KS and Tulsa in those days. Not much other than 2 laner's anywhere out here. My Grand Mother was always mad at him for not getting a Dodge or OD! Oh, and the highways in OK and MO had curbs! Some still do today. :confused:
As noted by others the OD was a component of the transmission that replaced the tailshaft housing of the normal 3 speed transmission.
Should not be too hard to find a good used OD transmission in those 'older' salvage yards.
With regards to brakes you could get some Chrysler brakes of the same or later era. Simple adaption and still stock CPDD parts and good parts repair availability.
Good luck and enjoy your 51 Plymouth.
