View Full Version : 1951 Willys M38 Electrical Conversion

09-06-2016, 01:00 PM
Hey folks, new poster here. Sorry if this has been covered, but I searched for the topic and came up short. I have a 1951 M38 that I purchased in pieces with a lot of new parts. I'm pondering converting it over from 24 volt to 12 volt. The entire instrument panel gauges (24v) are new in the box, but the rest of the electrical components are shady at best.

Question arises: Is this a good thing? Will 12 v turn over the L134 engine? I was told by the person I purchased from that I should decide whether to leave it 24v or convert to 12v before getting too far down the restoration. I'm sure I can sell the 24 v gauges since they are new in the box. So if I can/should convert to 12 v are there the things I need to convert???

Battery 12v
Battery cables
Generator & Regulator > Alternator
Instrument Panel Gauges All (Speedometer, Ammeter, Fuel level , Water Temp, Oil Press)
Oil Pressure Sending Unit
Oil Temp Sending Unit
Fuel Level Sending Unit
Plug Wires
Wiring Harness
Light Bulbs (Headlights, Instrument Panel bulbs, blackout headlight, blackout marker and service parking light, blackout taillight and stoplight bulb, service taillight and stoplight assy)

Did I miss anything or did I add more than is needed?

Thanks in advance!

09-10-2016, 12:55 PM
Just the fact that you were able to generate that long a list gives you the answer that there's a lot to it.

The M38 series had 24-volt systems because they were intended to be equipped with field radios (PRC-25, VRC-12 and others of various types). The first question, will a 12-volt system crank an L-134 - the answer is "of course - with a 12-volt starter". (The L-134 was originally cranked with a 6-volt system.)

The M38 series had the waterproof and radio suppressed ignition systems. The shielded plug wires and special distributor are pains and expensive - but maybe not more so that new ones if the old ones are still OK. Bulbs will have to be changed to 12-volt bulbs, but maybe not the actual light housings themselves. Look in the KWAS catalog and see if things match. Some gauges may need to be changed, and probably sending units with them. Speedometer is mechanical -no issue (I think).

The 24-volt regulator is expensive, but if the 24-volt generator is OK, probably not any more expensive that a 12-volt generator and regulator. If you change, you will have to modify wire harness to accommodate the new electrical connections. M-38's (at least some - I'm not an expert) had quick disconnect threaded connectors that are easy to work on in the field, but don't have easy civilian equivalents. Once again - KWAS catalog is a gold mine of information.

Good luck, and let us know what you do.

09-13-2016, 10:59 AM
Thanks for the feedback LarrBeard, but I have a few items I am missing...Batteries, Battery cables, plug wires, fuel tank and components, and complete wire harness...so those will need to be purchased. I could probably sell the Gauges since they are all new in the box and replacements in 12v are not really an issue.

And since I won't be running any field radios and such, I'm leaning towards a 12v system. That way I can be jumped in a pinch if needed. But still not 100% committed.