I have an engine in the project I purchased that I would like to test run before I go too much further with getting the whole truck together. It looks as though the engine is in good shape, but it seems like it would be a good idea to make sure. Before I turn it over at all, I will be soaking the cylinders with oil/atf.
BUT...at this point I am trying to make sure I understand what the minimum wiring layout will be. (The last time I did this was in the 1960s and I have NEVER worked with an alternator!) The truck came into my possession with a 12V alternator and a 12V starter...and no usable wiring to speak of. I will be using the foot switch to engage the starter. What can I use as an ignition switch? (The Electrolock is currently in pieces.) I assumed that I would be able to find a drawing on this site or on the VCCA site, but so far I have been unable. What gauge wires will I need? The coil I have says it is for 12V and that an external resistor must be used.
I am attaching a couple photos of the alternator.
Thanks!
Nick 1940 KC Model 1/2 Ton Pickup Project (with '37-'39 Bed and what we think is a '42-'46 Frame) Taos, New Mexico
Nick, I guess I will assume your truck has been converted to 12V because you mention 12V parts.
Ignition Instructions for just a short'ish motor run. NOT a vehicle run.... not charging battery
1. Forget the electrolock 2. Forget the alternator
Minimum wiring: using foot switch. 12V 1. 12V Battery pos cable to this starter mounted switch stud. 12V Neg battery cable to a motor bolt. 2. Wire from the "side terminal" on that switch to a 12V externally resisted coil.... positive terminal. 3. Wire from any temporary ("ignition") on/off switch's ON terminal to one side of ballast resistor. Example or anything laying around the shop. Non automotive is OK. House light switch 4. Wire from other side of ballast resistor to coil pos. 5. Wire from battery source to temporary ign sw batt terminal. No other wires.
Turn temp ign switch to ON and stomp starter. The alternator can be installed with no wires. just to run the water pump belt if necessary.
If this is a problen due to me not knowing what voltage you have or some other issues/questions, let me know.
Last edited by bartamos; 02/04/20251:07 AM. Reason: clarification/spelling
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
There is nothing much on the truck to convert, voltage wise. There is really no wiring and are no lights except those that are in the gauge cluster...and there is no wiring connecting that to anything else. Any wires that are still hanging around on the truck are just decayed fragments that will be removed.
Other than the gauges, fuel level sending unit and lights, is there anything else that will be voltage sensitive?
Nick 1940 KC Model 1/2 Ton Pickup Project (with '37-'39 Bed and what we think is a '42-'46 Frame) Taos, New Mexico
So you are, or have, converted from 6V to 12V system????????? Just want to be clear.
All bulbs, all electrical gauges, coil, heater blower motor, starter, alternator with built in regulator, horn........the fuel sender is not voltage specific.
I recommend a universal. prewired fuse panel. 12 circuit harness kit. Click.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
There should be a smallish wire (8 or maybe 10 gauge) from the battery cable terminal at the starter, going into the cab. That supplies battery voltage to the ammeter. Disconnect that wire and leave it loose for now. That will isolate the entire original electrical system and allow you to power up nothing but the ignition system with the wiring setup bartamos has described. That will keep from getting a "positive smoke check" and possibly a fire in what's left of the original wiring harness. For a test run, you don't even need a radiator or a fan belt- - - -just plumb a garden hose to the water pump inlet and run a small volume of water from the hose out of the thermostat housing. (Remove the thermostat) I have run engines that way while strapped down on a forklift pallet for extended periods of time, checking for oil pressure problems, rod knocks, etc. Good luck! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Make sure all the valves are free, oil each stem, tap valve stems with a rubber hammer or 2x4 to make sure they are free. Stuck valves will commonly bend a pushrod, or worse.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires. '47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle. '54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed. '55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
