Starting a 6 volt Engine

I am trying to get my newly rebuilt 1951 230ci 6cyl plymouth engine started. Its installed in a 1936 dodge sedan. Its a 6 voly positive ground system. I am by no means a mechanical genious. I can get the motor to crank and have no spark at the plugs. If I put one of those testers with the light in them to the small coil wire that goes to the side of the distributor it lights when the key is on so I assume I am getting power to the distributor, right? If I pull out the center wire on the coil and try to see a spark while cranking I do not get a spark. I am also not sure if I am using a condenser and points from the 36 in the 51 distributor, will that make a difference? Any help would be appreciated,

Get a 6 volt battery and hope you have not damaged too much by running it at 12 Volts.

Since your test light comes on at the distributor, voltage is flowing through the primary side of the distributor as it should. The ignition points in the distributor make and break the circuit to the chassis ground. When the points are closed, the primary side of the coil is energized. When the points open, the magnetic field in the coil collapses and causes a high voltage to be induced into the secondary winding of the coil. ThiS high voltage travels to the tower of the distributor cap and the rotor sends the voltage to the proper spark plug.

The first suspect is the ignition points. Make certain that the points are opening and closing. If the points are closed, flick them open with a screwdriver and see if you get a spark from the high voltage coil wire to the engine block. If you do, reset the disributor gap. If you don’t, make certain that you are getting voltage the to the ignition points. Check the condenser to be certain that it isn’t shorted.

BTW, I don’t remember the Plymouth using a 230 cubic inch engine until 1954 and only in the PowerFlyte model(automatic transmission). The 1951 Plymouth engine was 217 cubic inches and this engine continued to be used in the manual transmission models until 1955. The 217 and 230 cubic inch engines had the same block with the same bore, but the 230 cubic inch engine had a longer stroke. The 230 cubic inch engine was used in the Dodge from 1942 through 1959 (except for the V-8 models of course).

It’s not the engine thats 6 volts its the electrical system thats 6volts. With that same tester place the probe on the other side of the coil and crank the engine,if the light flashes the points are working.

When working with points,replace them at the first hint they could even remotely be the cause of your no start condition. Then start thinking about the ignition coil and condensor.

If I put one of those testers with the light in them to the small coil wire that goes to the side of the distributor it lights when the key is on so I assume I am getting power to the distributor, right?

RIGHT!! Now when you crank it, that test light should rapidly blink on and off as the points open and close…If the light stays on, the points are not closing or they are shot. With the points closed, the coil circuit is grounded and there will be no voltage at the distributor…Do you know how to set the points??

Make sure the carbon button in the center (inside) of the distributor cap is there, and that it springs back when you push on it.

Yes it should blink rapidly, but you must put the test light on the other terminal of the coil, you won’t get a light flash if you leave the test light on the feed terminal of the coil, you must have the test ligh on the distributor side of the coil to see the light flash.As you have stated.

I agree with the other posters that your problem is probably points related. Be sure they are good and properly gapped, .015" when open (in the absence of a dwell meter to set them). The question isn’t whether you have the early points installed in the later distributor, but whether you have the correct distributor installed in the later engine. I don’t know what differences there might be, but the spark advance mechanisms, and possibly the drive gears are bound to be different.

Many six volt systems have been changed over to 12 volts, even those with + grounds. Switching the polarity is not an issue. The electrons are going to flow from - to + regardless of how you hook up the battery. If you install a 12 volt generator, you just have to re-polarize it. Lots of folks use an 12 volt alternator for an easy change. The other things you have to change are the bulbs and generator, if you don’t go the alternator route. The starter doesn’t have to be changed. It is much heavier built than a typical 12 volt starter. Just look at theose beefy windings. I’ve seen six volt starters run on 12 volts for many years. You will want to install a ballast resistor in the system to step down the voltage to the points and coil to six volts. Otherwise you will fry the points and condensors pretty quickly. Most of the old systems put 12 volts to the points only during cranking to provide a hotter spark for starting. That’s the way it was done for many many years after 12 volt systems came out.