1937 Plymouth Engine Basics

[37Plymouthguy]

I'm restoring a 1937 Plymouth, and have the rebuilt engine bolted back in place. Since this was a complete "body-off" restoration, all of the electrical equipment has been removed, and now I need to know the bare minimum required to just start the engine. The distributor is in place, as is the starter, generator, and spark plug wires. Besides the battery, what else do I need to start the engine? Thanks for your help. Willard Crawford kart32@aol.com

[JACK M]

Maybe a solenoid if it uses one of those.
Radiator and coolant. You could pop it off without a radiator but not recomended. (bare minimum for a few seconds only)
A carburator and fuel supply. You can gravity feed this with a boat can or similar. Or put the fuel pump on it and drop the supply line into a gas can.
Maybe a down pipe on the exhaust manifold.
Power to the coil.
If you are just wanting to hear it run then dont worry about the generator.

[37Plymouthguy]

Hi Jack,

Sorry, I should have specified electrical requirements only. Do I understand correctly that all I need now is a solinoid? Thanks for answering. Willard Crawford kart32@aol.com

[jazzer3]

You will need a ground from Positive battery to the engine, negative from battery to starter(my 40 Plymouth had no solenoid it had a foot controlled starter switch). A wire from Negative battery to negative side of coil and a wire from positive side of coil to distributor (points). I think that should be enough wiring to start the engine. You will have to engage the starter.
There are no provisions in this set-up to allow for short circuits so be careful and don't make sparks near the battery, that's my disclaimer!
Good luck,
Jay

[Ian.Harrold]

This may help. I have no idea of the wire gauge though.

[JACK M]

If it has a foot controled starter switch the you do not use a solenoid.
Jazzer has it right on the rest.

[37Plymouthguy]

Thanks Jack and Jay, I think you have given me the info that I need to get it started. One more thing.
Will I experience any problems starting it with a 12 volt battery, or do I need to find a 6 volt battery to keep from frying something? Thanks again guys. Willard Crawford

[37Plymouthguy]

Thanks for the schematic Ian. I have pieces of the original wiring to get the gauges from. Willard Crawford

[jazzer3]

For just firing the engine you should be OK, many people that convert to 12 volts never do anything to the starter if you run the engine for any length of time you probably will burn out the coil.
Jay

[keiser31]

For just firing the engine you should be OK, many people that convert to 12 volts never do anything to the starter if you run the engine for any length of time you probably will burn out the coil.
Jay

Yep. Been there, done that.

[JACK M]

To save the points and coil you should install a ballast resister in the line between the battery (or switch) and the coil. Its a little ceramic covered winding that reduces the voltage to the points. All cars with 12 volt systems and points had one of these. Again if you are only going to run it for a few seconds the points will last that long, but they will burn up soon without the resister.

[37Plymouthguy]

Thanks for the tip, Jack. I'll do it. Willard

[Rusty_OToole]

I have started 6 volt cars on 12 volts and run them for up to half an hour without hurting the coil, however this is taking a chance. Recommend no more than 10 or 15 minutes unless you get a resistor to drop the voltage. Then it does not matter.

[37Plymouthguy]

Hi Rusty,

Thanks for the info on the resistor. Does that mean that I could convert the 6 volt system to a 12 volt system by installing the resistor, or would I have to also install resistors on all of the lights, horn, etc. ? If so, is that a big job? Thanks. Willard Crawford

[JACK M]

Te horn wont care as the starter wont either. You would just have to replace the bulbs W/12 volt ones.
However if you are going for ORIGINAL ......

[37Plymouthguy]

Hi again Jack,

Thanks for the info. I'm not an "orignal" guy, I just want to rebuild the car so it's driveable. If I go with 12 volts, do I need a 12 volt generator and regulator? Also, who do you think has the best after-market Plymouth parts house with Internet access? Thanks again for your help. Willard Crawford

[JACK M]

Hi Willard,
I would go with a one wire alternator. They are about a hundred bucks and trouble free.
Espessially if you are going to change guages. Nowadays we use volt meters as opposed to amp guages. One may be able to run the one wire thru the original amp guage but the alternator usually puts out more amps than the guage will handle.
I am working on a car now that I want to keep at 6 volts pos ground. I just ordered an alternator that fits the bill as I found out that I dont know as much about generators as I thought.. This way the gas guage will still work. I also had them turn the amps down to 50 amps as My ammeter goes to 50 and the guy I ordered it from is building it special for me.
I should have mentioned for 12 volt the gas and any othe electric guages will need what they call a "runtz". availabe from speedway motors. A neet little device that I have used in the past. Here is a link. Runtz - Speedway Motors, America's Oldest Speed Shop
You can order the one wire 12 volt alternator from these guys too, it will be negative ground.
I have been ordering street rod and racing parts from these guys for years.
Another thing to consider is that your car is originally pos ground so if you go 12 volts and want to use original guages this possible to do with neg ground but you will have to reverse the hook up on your ammeter.
As for Plymouth aftermarket it depends on what you are lookig for. I just ordered some tranny qaskets and seals from Andy Bernbuam. Andy Bernbaum Auto Parts for Chrysler's cars from 30s to 70s There are others as well, Roberts motor parts comes to mind.

Have fun !!

[JACK M]

Let me ad that if your original 6 volt stuff is still in working order it may not be worth the hassle. Six volt cars can still be dependable.
The guys that I run with will usually convert as they may want to run modern stereos and such. Also lets face it guys these days are just more comfortable with up to date electronics.

[ply33]

Let me ad that if your original 6 volt stuff is still in working order it may not be worth the hassle. Six volt cars can still be dependable.
The guys that I run with will usually convert as they may want to run modern stereos and such. Also lets face it guys these days are just more comfortable with up to date electronics.

A lot of the modern electronic trinkets (smart phones, GPS units, MP3 players etc.) actually charge off of 5v DC. Easy to tell: If it charges off of a USB cable it is 5v. And it is pretty easy to regulate a 6v car electrical system (6 to 8 volts) down to 5v.

If you want a high power stereo or air conditioning, you'll need 12v. But for a lot of the modern toys you don't need to convert to 12v like you used to when CBs and clunky old cellphones were designed around 12v chargers.

[JACK M]

A lot of the modern electronic trinkets (smart phones, GPS units, MP3 players etc.) actually charge off of 5v DC. Easy to tell: If it charges off of a USB cable it is 5v. And it is pretty easy to regulate a 6v car electrical system (6 to 8 volts) down to 5v.

If you want a high power stereo or air conditioning, you'll need 12v. But for a lot of the modern toys you don't need to convert to 12v like you used to when CBs and clunky old cellphones were designed around 12v chargers.

I remember a recent thread that sugests a Walmart stereo that uses batterys at 9 volts will work with six volts.
My 52 Plymouth has no radio and rarely do I miss it.

[37Plymouthguy]

Thanks for the info, Jack and Ply33. I decided it would be easiest to stay with 6 volts, so I just bought a new 6 volt battery. I won't be adding any fancy stuff like a stereo or A/C. In fact, it won't even have a radio or heater. (I live in the California desert.) Tomorrow I'll try to fire it up with the 6 volts. Cheers. Willard Crawford

[Towbar2]

I bought an Optima 6 volt for my '38 Dodge Bros. in 2000 and it is still good, the car can set for weeks and it will fire off whenever I go stand on the starter. These batteries don't freeze so bad either. Good luck.

[JACK M]

I use Optima batterys too.
Here is a bit of info that was passed on to me regarding freezing. I charged battery wont freeze, a dead one will.
Good luck on your test run !!

[Rusty_OToole]

Don't try to change your Plymouth to 6 volts. It's a real bag of worms. I have changed cars and tractors in the past, and it's not worth the bother and expense. Easier and better and cheaper to keep the 6 volt system and just fix whatever is wrong with it.

As for all the guys who say it is easy, they are full of it. What really bothers me is that these wisenheimers talk some poor sucker into trying to change his car over, then when he gets in a mess, they are never around to answer his questions.

Just keep it 6 volts, buy an Optima battery and be happy.

[Towbar2]

True: "a charged battery won't freeze." However, freezing temperatures cause the specific gravity of electrolyte to become reduced thus effectively shortening the "charged state dwell" period. The further below the freezing mark, the less time the battery will remain charged in storage and the sooner it will enter the freezing phase itself. A trickle charger is always a good preventive when cars are stored in unheated spaces during extremely cold days. The Optima gel media is good way down to -40 ish [at that point both the Celsius and Fahrenheit scales are exactly the same.]