Like to get others opinions on electrical wiring. Have a 54 GMC 150-24 Truck. Going to do a full restore someday, buy figure I'd get the wiring replaced (snow day project). It's a 6v setup right now and would like to see if there is a source out there to convert the generator to an alternator yet keeping it's original look. I googled a couple years back and lost the link to one. Assuming the gauges I'll need to replace to 12v, the guy who is the expert at rebuilding gauges does not do 54 GMC, just earlier ones. Anywhere I can get gauge kits to rebuild mine? Or keep it as 6v is fine with me to keep it's originality... I am very good with electrical and can rewire or modify most wiring if I have a good wiring diagram, where is the best place to get one? Have a couple original wiring but hard to read.
Also open to any suggestions or add on's to the wiring, etc. before I get started?
Sorry for the many Q's, new at this and want to do it right the first time.
Question #1: yes there is a alternator made to look like a generator. It’s notoriously expensive and not necessarily reliable. Sold by many of the resto-rip-off places.
As for your other questions, I’m sure someone will chime in soon.
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
Will check Jegs, Thank You. Talked with a guy, thing Sam? Who said he only works on 40 something to 53 gauges as they were changed 54 and up. Unsure why. Hopefully I can find a source to either rebuild my own, find someone that rebuilds or buy new.
Saw a link somewhere that it can be converted, hoping I can find a kit to do it myself, etc. Up in the air to either keep 6v or change to 12v, lots of pros and cons, one of them being if I needed a jump start, LOL.
I've been driving this heap as a daily work truck for about a year. It's 6v and works perfectly. It cranks over as fast as any 12v car. The key is making sure you have 00 (2/0) gauge battery and ground cables along with a properly functioning 6v generator and voltage regulator.
The PowerGen AC generators that are bolt in replacements for the original Delco DC generators were $500 each the last time I looked. They're probably $600 or more now.
Here are two very good companies that make wiring harnesses for antique cars.
Rhode Island Wiring Service, Inc. Wiring harnesses for all years, all makes and models 567 Liberty Lane, PO Box 434 West Kingston, RI 02892 (401) 789-1955 http://www.riwire.com/
Last edited by Otto Skorzeny; 10/21/20225:02 PM.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
https://brillman.com/ is another highly rated wiring harness company for vintage vehicles. If your vehicle had cloth covered wiring originally that is what they do. I used one for my 47 Dodge 1/2 ton and I am very happy with it. They do make them to order. Takes about 6-8 weeks to get it.
Jegs sells a plastic covered wiring schematic with colors same as original. Your gauges on your truck should be same as ‘47-‘55.
Ed in CO
That supposedly 55 GMC wiring diagram shows a negative ground 12v battery and an overdrive, neither of which were available on 1st series 55 or earlier GMCs. I wouldn't depend on it.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Being that you are weighing the option of going to 12 volts means you have already decided not to go 100% original.
The companies who provide wiring kits focus on the largest part of the market so they can sell more product and make more profit (free enterprise). That market pie is of people/shops who take classic/antique vehicles and turn them into cruisers, street rods and such. If you purchase one of these kits it will most likely have wiring for a modern GM steering column, 12 volt alternator, 12 volt dash gauges, V8 engine sensors and other modern features.
There are a few companies who make original kits with cloth wiring but I would advise against it because of the expense and it is only logical to use them on 100% original vehicles.
Since you are good at wiring, I would buy the "good grade" professional parts I needed and make my own wiring harness. Try as hard as you can to remove the old wiring intact. You use this as a template. The old scheme was to use the body and frame for a ground path (especially lights and lamps) but I prefer a separate ground wire so I don't have the common old truck grounding problems.
I avoid adding-in voltage regulators and dropping resistors to make a 6 volt device operate on 12 volts because of the energy waste. I would purchase a 12 volt fuel gauge and associated tank fuel level sensor with the resistance to satisfy the gauge. Oil pressure (copper tube) and water temperature (gas filled tube) gauges are not electrical on Chevrolet BUT I have no no documentation to advise me what is used on GMC. The ammeter will work with a 12 volt alternator. All the dash lights are changed over to equivalent 12 volt replacement.
Last edited by buoymaker; 10/21/20227:52 PM.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
Buoymaker, when you say you omit the body/frame ground, does that mean you run a ground (-) wire from all the accessories directly to the battery?
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
The negative ground 12V trucks were V-8’s, whereas pos. ground 6V were 270 sixes w/ no OD. The print allows both interpretations so only need to offer one print. Easy enough to figure out if options are known.
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.
The corner of the diagram that I can see refers to V8 engine options and 12V negative ground. Neither would be appropriate for "same as 47-55" as stated in Ed's post..
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
