The Stovebolt Site Forums The Parking Lot Big Bolts Getting a 1954 503 truck going

There’s a 1954 GMC 630 series (634-50-Z1153 = 183WB, 503 engine) in my uncle’s field that I was thinking about trying to fire up sometime just for the heck of it. No idea how long it’s been sitting but doesn’t look too bad and still has an antique plate on it.

Anything important to know before trying this? I have a fair amount of experience with old vehicles from owning two 55 Packards for a couple years and watching a bunch of VGG.

Was planning to see if I can get a 6V battery from a recycler to use. I can charge it with a power supply. I know they offered these with a 12V conversion but I checked and this is 6V.

Here's some pictures. Odometer shows about 28k but it's hard to imagine that it's not rolled over.

Look at some of the other threads about getting one back to life. Pull the valve cover and lube everything, try to turn the crank by hand.

For the purposes of getting it running, just install a 12V ignition coil and disconnect the BAT wire at the voltage regulator. You can crank the engine with 12 volts without damaging the starter and nothing much else will be affected by a short run at the higher voltage. Be sure to lubricate everything thoroughly, and turn the engine several revolutions by hand before running the starter. Repair parts for a 503 are as scarce as a chicken with lips, so don't take a chance on trying to force the engine to turn over with the starter if it's even slightly sticky. Engines that sit for long periods of time tend to get the piston rings rusted to the cylinder walls, and/or valves will stick in their guides. Good luck!
Jerry

As mentioned, put some oil or ATF in the cylinders before turning the engine over. And pull the valve covers and make sure all the valves are moving freely.

Nice 630. Looks to be an ex fire truck judging by the running boards, and that flared portion just past the doors. Got any more pic.s

We have a pretty comprehensive Tech Tip on starting a long-dormant engine -- Check here -- "Bringing a dead engine back to life."

It may seem like like a long and tedious process when you have a real urge to just put some gas to it, a fresh battery and ... let'r rip. But .... Why take a chance on ruining a possibly good engine because you skipped over something simple?

Rebuilding a 503 -- horrifically expensive if even possible.

Checking the oil, or for a stuck piston and taking a little time to correct -- easy and cheap.


We put that Tech Tip together from a lot of experience in bringing dead engines back to life. We even field tested it on a truck we (the ODSS members) eventually drove out of a swampy location where it had been for decades. We even got the brakes working fine. BUT ... we took our time and methodically went through the checklist before we just sprayed ether down the carburetor throat, put the 12-volts to her and cranked away. That engine and truck has had a lot of miles put on it since then (it's collectively owned by the members of the Old Dominion Stovebolt Society). You can read about it, and see pictures & video, here

Thanks for the advice everyone. I will check out that article. Obviously it's winter now and the truck is outdoors so I don't know when I'll next stop by, but you never know when you'll get a half decent day even in winter

As requested here are more pics. Bonus points if you can identify the item under the hood. I assume a plate resistor, but don't know what for.

Looks like a Selenium Rectifier to me, used in conjunction with a big generator/alternator like the Leece Neville units. Did the truck have more than one battery for radios or electronics?

Mike B

I'm not sure but it does have a dump bed or something. The hydraulic levers are visible in the rear end pic on the left.

Looks like fire truck body made by same company as mine, put shorter bed on mine, two speed rear.

Ed

Interesting, I'll have to see if anyone knows the history on it. Why would a fire truck be a flatbed?

Prolly because at some point, someone (with a torch ...) needed a flatbed more than they needed a firetruck.... but a retired firetruck at an auction was all they could afford ...

My firetruck almost became a flatbed that way. But someone else needed a firetanker more than I needed a flatbed so my former truck is still a firetanker.

At work, we have a service truck (parked now in the junk lot) that started out life as an ambulance for our town's rescue squad. They cut the ambulance box off, ducktaped plywood across the back of the cab and slapped a service body on it and voila ... service truck.




John

To carry another smaller truck or equipment?

The finned item under the hood is a selenium stack rectifier- - - -it turns the AC current produced by that big alternator into DC to charge the battery or batteries- - - -usually more than one for a rig that size. Are you sure that's a 6 volt system? Most alternator equipped vehicles were 12V even back then.

There should be a label somewhere on the alternator indicating voltage, and possibly ground polarity. Most GMCs in the early 1950's were positive ground.
Jerry

I took a picture of a data plate, not sure what on, saying 7 volts, 100 amps.

The Leece Neville Co.

OK- - - -you've got a real oddball there- - - -a "6 volt" high amperage alternator. It will probably produce around 7.5 volts when working against a fully charged 6V battery. Once you're sure the engine turns freely and there are no stuck valves or piston rings rusted to the cylinder walls, I'd suggest completely disconnecting the charging system and doing the initial startup on 12 volts. No point in dumping a bunch of money into an obsolete electrical system only to find out the engine isn't a good candidate for restoration. Most of the BIG GMC' sixes (413 to 503) got worn out and scrapped 50 years ago or more.
Jerry

Don't let anything happen to that selenium rectifier and if it does, don't breathe the fumes from when it burns. Those are pretty common on old 1950s jukeboxes and other hi-fi gear, and are notorious for burning up and being super toxic while doing so.

If you just want to replace it, finding some high-amperage silicon diodes will be pretty easy. You could probably use the diode bridge out of a 10SI alternator without too much field engineering.

It would be a lot simpler to just swap to a later style of alternator. There are a few versions of the 10SI that have been converted to 6V positive ground for Ford N-series tractors. Since you're not likely to be running the full electrical system the fire truck needed (lights, siren, radios, etc.) you probably won't need the 100 amp output of that big alternator.

I've seen the 6V positive ground alternator, a lot of the old, like 1920s old, car guys are doing the conversion if they intend to drive the vehicle. I can't imagine the patience required to do a 600 mile road trip in a Model A.. but folks are doing it, and the Delcotron solves most of the electrical issues.

One of the first things I did on my '65 C60 was to modernize the charger whirler and now I've got 150 amps of RV battery charging when I start it. Of course, that includes the 6 gauge wiring from output to battery.

Back in 1968, I participated in a Model A road trip from LA to Dallas, to New Orleans, to Kansas City, and back to California by way of Denver. We had 2 pickups and 6 guys (two riding in the back of my pickup fitted with a grapes of wrath canopy over the bed.) The ONLY issues we had were 15 (yes 15!!) flats on my truck, and a cracked clutch lever on the other one which was fixed by a quick trip to a junkyard (I think in Kansas.) Both trucks were mostly stock, although I had a Model C 4 cylinder engine in mine. We had absolutely NO issues with the stock electrical systems. Simple as dirt. We had a blast!

I'm in the process of running a #0 cable bumper to bumper on the service truck I just bought to power a plug-in jumper cable connector on both ends. I'll have a set of 20 foot booster cables, also made from #0 welding leads. The truck will be equipped with two Group 30 batteries wired in parallel and a 100 amp alternator. The same connector on the rear will allow me to plug in and power the winch on my car hauler trailer.
Jerry

Hph, I would not doubt if your truck was a firetruck and those miles are original. Mine was converted to a flatbed after it was sold and has 16k miles. Looks like you have some extra switches where radio knobs would be? Holes in the roof/fender for lights/siren would be a good sign it was.

@klhansen wow, that's amazing! The last Model A thing I watched was when Vice Grip Garage bought one and drove it 600 miles home. It did make it, but had some pretty big coolant and oil leaks, NTM the wipers and roof were more suggestions than actually effective at keeping rain out ;-) However there's a lot to be said for the KISS rule of engineering, which is probably why many of us are here. New rigs require expensive diagnostic equipment and knowledge of CAN bus protocols to fix pretty much anything. And can be bricked-rendered unusable-at any time, for any software glitch the factory doesn't feel like fixing. No, thank you. And I like electronics as a hobby!