Instrument cluster upgrade 1974 C10

[JohnTaurus]

Hope I am posting this in the right place.

I have a 1974 Custom 10 (Inline 6), and from the factory, it has: warning lights, speedometer and fuel. That's it.

I bought a full gauge cluster off eBay from a 1973 V-8 truck. I have since been rebuilding it and preparing it for my truck.

Here is what I've accomplished thus far:

I had the tachometer rebuilt and recalibrated for the 6 cylinder engine and HEI ignition.

I purchased a reproduction clear lens

I purchased a reproduction fuel gauge

I purchased a reproduction printed circuit board

I purchased a factory voltage gauge from a slightly newer square body, I've since been informed that this may not work?

My question: what next?

Does each gauge have to be wired individually or will all but the tachometer work as is?

I have little experience here, but I'm willing to do what it takes to put this full gauge cluster in my truck.

I currently have aftermarket Equuis gauges for oil, temp and tachometer. I want those gone. The tachometer uses a 3 wire connection like the GM tachometer. What are the chances that this wiring will work for the tachometer in the cluster?

If I can help you help me, let me know (photos, etc).

I really appreciate your help, guys. Thanks in advance!

 

[Rickf]

I just replaced the ammeter with a voltmeter in my '74. One side of the ammeter should be switched +. 1) I removed the right side (as seen from the back of the ammeter gauge) mounting clip to printed circuit board. 2) made up a short wire for the voltage gauge ground and attached it to the oil pressure gauge mount. I hope this makes sense.

 

[JohnTaurus]

I just replaced the ammeter with a voltmeter in my '74. One side of the ammeter should be switched +. 1) I removed the right side (as seen from the back of the ammeter gauge) mounting clip to printed circuit board. 2) made up a short wire for the voltage gauge ground and attached it to the oil pressure gauge mount. I hope this makes sense.

Yes it does make sense. I really appreciate your time and advice!

I've ordered a factory 1974 GM Light Truck manual, so I believe it will give me the other information I need to make this work.

Again, thanks Rick!

 

[Rickf]

LMC lists an "add a tachometer kit", there may be other vendors.

 

[Gman73]

John if you’re using a factory cluster with the printed circuit on the back there are two versions of that one for a tach and one for no tach. Lic list both the replacement cost is about 60 dollars, I have a 73 myself without tach but am going to get the tach version. Where your file gauge is is where the tach goes lmc shows both pretty well

 

[JohnTaurus]

John if you’re using a factory cluster with the printed circuit on the back there are two versions of that one for a tach and one for no tach. Lic list both the replacement cost is about 60 dollars, I have a 73 myself without tach but am going to get the tach version. Where your file gauge is is where the tach goes lmc shows both pretty well

Well, I already bought a reproduction printed circuit board for a 73-74 tachometer cluster. I don't think this install will be too bad.

 

[Gman73]

no you got the right one that’s what I was pointing you towards

 

[SirRobyn0]

I think you will need a different oil pressure sending unit and temp sending units as they have different part numbers for lights and gauges.

 

[75gmck25]

All 73-75 (and maybe later) had a mechanical oil pressure gauge and an ammeter. Going from ‘73 to ‘74 cluster should work fine.

I swapped a ‘74 tach cluster into my ‘75, and then converted the ammeter gauge pod to a voltmeter. Some observations:
- tach cluster (except the tach itself) just plugs in as direct replacement to non-tach cluster. Tachometer is connected with a separate 3 wire pigtail .
- original tachs of this vintage have circuit board problems across all GM vehicles. There are lots of tach repair board for Corvettes, but they do not fit a squarebody tach. My tach works about 95% of the time, so I just left the old one in place.
- tach hookup is a simple 3 wire pigtail (power, ground, signal) and if you have HEI the signal wire just connects to the tach terminal. Original tach signal wiring had a noise filter in it, but it does not seem to be critical to have it
- converting to voltmeter only requires some simple wiring changes. You just buy a voltmeter from a newer truck connect it to power and ground in the cluster with some jumper wires . The font and color of the new gauge will probably be a a little different, but does not really stand out.

 

[JohnTaurus]

All 73-75 (and maybe later) had a mechanical oil pressure gauge and an ammeter. Going from ‘73 to ‘74 cluster should work fine.

I swapped a ‘74 tach cluster into my ‘75, and then converted the ammeter gauge pod to a voltmeter. Some observations:
- tach cluster (except the tach itself) just plugs in as direct replacement to non-tach cluster. Tachometer is connected with a separate 3 wire pigtail .
- original tachs of this vintage have circuit board problems across all GM vehicles. There are lots of tach repair board for Corvettes, but they do not fit a squarebody tach. My tach works about 95% of the time, so I just left the old one in place.
- tach hookup is a simple 3 wire pigtail (power, ground, signal) and if you have HEI the signal wire just connects to the tach terminal. Original tach signal wiring had a noise filter in it, but it does not seem to be critical to have it
- converting to voltmeter only requires some simple wiring changes. You just buy a voltmeter from a newer truck connect it to power and ground in the cluster with some jumper wires . The font and color of the new gauge will probably be a a little different, but does not really stand out.

Oh my God, man, thank you so much for this reply. I'm so excited to get this in now!

The guy I sent my tachometer to replaced the circuit board. He also had to do something else, which costs extra, that he said was because my tachometer was very, very early production. Either way, he guarantees itll now work with my 6 cylinder + HEI.