Skip or someone else with old electric gauge books

[GPster]

Here's an oddball bunch of clues that might help someone find me an answer. I'm looking at a gauge cluster from a GMC truck between '47 and probably '52. This seems odd in that it had an electric temperature gauge and I need a sender for the engine or enough information about the original sender to replace it with one that might better function in an up-graded (12 Volt) system. The gauge cluster that I have acquired might have been from a big truck because the oil-pressure gauge reads 0-60 and the amperage gauge  reads 50-0-50 amps rather than discharge-charge. The matching speedo that came with the set reads 0-80 which would cause you to think that it was from an early model. The Chevy gauge cluster that I have has a direct reading temperature gauge with a bulb rather than an electrical gauge/sender set-up. I would rater not change the gauge because the Chevy gauge works to indications of 100 - 212 and the GMC gauge is working to a indication in it's cluster with a 220 degree top range. I would rather have the correct gauge operating within the correct scale. Anyone have an old book that might indicate a number for a sender? Because the original sender would have been used in a 6V circuit and will now be in a 12V circuit would I be better using an original sender and a voltage re-ducing resister or would I be better finding a sender that would operate in the same range (ohms ?) on 12v ? The GMC cluster that I've acquired is in better shape than the Chevy cluster that I have and I got a matching speedo with it. The GMC cluster has the correct oil pressure gauge for the engine that I'm using and I simply want to be simple and use it all, correctly. GPster

[enjenjo]

In my searching for senders for 50's GM cars and trucks, the sending units usually fit both 6 and 12 volt guages, so a stock type sender will probably work with a 6 volt guage, and a voltage reducer.

Joe, I may have a full set of GMC guages available in a week or so, working guages, that at this moment are still in use.The oil pressure is mechanical, 0 to 60, the temp guage is also mechanical.

[GPster]

I'm not above going to a mechanical temp. gauge. What I have done is help Sumner clean out his rental building so what I have are replacements that he had used when his truck was still running stock. My engine was originally metered with a mechanical gauge so the correct fittings are still in the block for the bulb. This past weekend I received the lastshipment of parts that go with my cab purchase. Got one more door/window molding and vent window assembly, parking lights,dome light, hood latch mechanism and window winder handles. If I make another build day this stuff will be more barn fill for you. If this all comes together there will also be a Chevrolet truck gauge cluster with a 30# oil gauge in it that you can add to the shed. When the GMC gauges appear see if the windshield defroster ducts can appear too. I'll also be looking for a couple of headlight buckets. Anything that I can put a couple of bulbs in and mount on my lightbar. Even something that's 5 1/4" (?) that I can use the dual element bulbs from a quad headlight set-up. I probably won't drive it at night but I'd like to appear legal. Boy, am I typey, GPster

[enjenjo]

How about a set of WWII GMC deuce and a half headlights? I have a pair that are in great shape. they are actually a pretty nice looking light with a painted rim. Yours if you want them.

[GPster]

Oh goody, nothing to wax or polish. Just what I had in mind. If they're already painted camo then I'll have my color scheme decided. I'm sure they're of the style I have in mind. Don't miss a sale but I'm sure I'll take them. Now I can start studying WWII and get an idea what they'll look like. GPster                                                                Keep talking!!!!!!! Some of us need to stay awake.

[enjenjo]

They are yours Joe. I may have some blackout parking lights too. As I recall, these lights are OD green with some flecks of red on them.

[1FATGMC]

Joe how about hooking up a sender, about any sender, to the temp gauge on the bench with the sender reading some water that you can heat and have a thermometer in the water to see how the sender and gauge respond/correlate to the actual temp as reported by the thermometer.

You then might be able to put a potentiometer in the electrical line if it reads high and turn it until the gauge reads right.  Then take a reading of the resistance of the pot and replace it with a resistor of the correct size.  Make sure the resistor has enough amp capacity (watts) so that it doesn't overheat.

This is all a guess as to what might work,  Sum

[GPster]

How about a set of WWII GMC deuce and a half headlights? I have a pair that are in great shape. they are actually a pretty nice looking light with a painted rim. Yours if you want them.

Got to looking at the "Best of the Web" at military vehicles and the pictures that I found didn't give a real good picture of the headlights on a "Duece and a half" but then I got to thinking that the vehicles look familiar. There's one parked less than a mile from here. It had been converted to a "drilling rig" but the headlights were still on it. Those headlights will be wonderful, I'll take them. Now that that's done I'll see if I can weld up-side down and side-ways. GPster

[moparrodder]

How about a set of WWII GMC deuce and a half headlights? I have a pair that are in great shape. they are actually a pretty nice looking light with a painted rim. Yours if you want them.

Frank, You better double check those deuce and a half head lights, the ones that were on ours at the fire dept were 24 volt as well as the blackout lights and the dash lights too.  We found that out when we converted it to 12 volt and all the lights were real dim untill we changed them all out. Just a thought.  Bill

[enjenjo]

Frank, You better double check those deuce and a half head lights, the ones that were on ours at the fire dept were 24 volt as well as the blackout lights and the dash lights too.  We found that out when we converted it to 12 volt and all the lights were real dim untill we changed them all out. Just a thought.  Bill

Joe can just change the bulbs to 12 volts, he is using them on a pickup.

I have done some 12 volt conversions on old military vehicles. Ignition is the hardest part. Some of the coils are unique to 24 volt systems.

[Pep]

Joe how about hooking up a sender, about any sender, to the temp gauge on the bench with the sender reading some water that you can heat and have a thermometer in the water to see how the sender and gauge respond/correlate to the actual temp as reported by the thermometer.

You then might be able to put a potentiometer in the electrical line if it reads high and turn it until the gauge reads right.  Then take a reading of the resistance of the pot and replace it with a resistor of the correct size.  Make sure the resistor has enough amp capacity (watts) so that it doesn't overheat.

This is all a guess as to what might work,  Sum

That's how I would attack it....Another option would compare  the reistance of a modern guage to the old one then use a resistor in series or shunt in the old one( depending on which way the readings are ) then use the modern sender.

[GPster]

I happened on a GMC site that has a duplicate of my gauge cluster. He is listing it as a '47 to early '51 cluster and it matches mine with an electric temperature gauge. I wrote to him asking about the sender but haven't received a reply. So I've at least nailed down the application and year. Decause this will be screwed into a '53 Chevy six I don't have much doubt that the correct sender will fit my block. So if anyone has an old book and can furnish me a part number I can check at the swapmeets. I mentioned to the vender that I would buy the sender that would work his gauge cluster to insure his reply. We'll see. If nothing else, if I had a part number and a manufacturer maybe I could pick their brains and at least get the ohm rating and then do the mathematical calculations to come up with one that would work on a 12V system without a voltage reducer. I understand the action with an ohm meter and a potentiometerbut I am at a loss as to someone close that has the equipment to help me that way. I get confused easily. Ebay has a partial gauge cluster with a mechanical temperature gauge that reads in the correct range. Maybe I'll bid on it Sunday night at it's closing if my grandson's first birthday winds down for his bed time. GPster

[Skip]

I've found that most forties and fifties 6 volt temp gauges will NOT work properly with late model senders.

I use the correct sender and use a Radio Shack 273-1815 (set to 6 volts on the switch) in series with the gauge power wire.

[GPster]

I've found that most forties and fifties 6 volt temp gauges will NOT work properly with late model senders.

I use the correct sender and use a Radio Shack 273-1815 (set to 6 volts on the switch) in series with the gauge power wire.

This is part of the reason that your name appeared in the question. I need some help in finding out what the original sender was. I haven't been able to come up with any information on what the original sender was, who manufactured it or what range it operated in. I've been impressed with your answers to questions like this and I thought maybe you had a fileroom with this information in it. GPster

[Skip]

I've found that most forties and fifties 6 volt temp gauges will NOT work properly with late model senders.

I use the correct sender and use a Radio Shack 273-1815 (set to 6 volts on the switch) in series with the gauge power wire.

This is part of the reason that your name appeared in the question. I need some help in finding out what the original sender was. I haven't been able to come up with any information on what the original sender was, who manufactured it or what range it operated in. I've been impressed with your answers to questions like this and I thought maybe you had a fileroom with this information in it. GPster

When I'm looking for something like this, I get onto one of the restoration suppliers and they can usually come up with an NOS or direct replacement sender.

I would venture a guess that the senders would be the same right up to '54 'cause that's the last year GM was 6 volts.

Fuel gauges, on the other hand, can be current sensing OR voltage sensing back in teh six volt era.

Once they switched to 12 volts, all bets are off.

For instance, the '79 Super Six in my '72 Dart needs to have teh '72 temp sender, otherswie, teh temp gauge is grossly incorrect......and the car originally had a 225 slant six in the fir4st place.  The '79 slant six sender isn't compatible w/ the '72 gauge though.