Gauge Cluster Swap

[BigBlackChevy77]

So I was able to pick up a gauge cluster for free today when getting some 0arts off an old square. One thing I snagged was the gauge cluster as it has actual gauges instead of the warning light system I have. The donor truck is a 1979 c20 custom deluxe key truck is a 1977 k10 custom deluxe. The owner is keeping the current harness so I was wondering before I tear apart my dash would I be able to use this style gauge cluster ? Like I said mine currently has a series of lights that appear when there is an issue and this one has a gauge to show temp oil pressure ect.

 

[75gmck25]

I believe that a '77 and '79 should be a direct swap, since by then they both had a voltmeter and an electrical oil pressure gauge. However, you do need to compare the wiring diagrams to be sure.

You will have to buy the gauge sensors for water temp and oil pressure if all you have now is lights. The oil sensor is a little hard to reach because its on the top, rear of the engine near the brake booster, but not that hard to replace. The water sensor is screwed into the driver's side of the block, and the challenge there is to find a sensor with the right resistance profile. There are several sensors that fit and work, but some of the replacements make the gauge read too high or too low.

Bruce

 

[BigBlackChevy77]

I believe that a '77 and '79 should be a direct swap, since by then they both had a voltmeter and an electrical oil pressure gauge. However, you do need to compare the wiring diagrams to be sure.

You will have to buy the gauge sensors for water temp and oil pressure if all you have now is lights. The oil sensor is a little hard to reach because its on the top, rear of the engine near the brake booster, but not that hard to replace. The water sensor is screwed into the driver's side of the block, and the challenge there is to find a sensor with the right resistance profile. There are several sensors that fit and work, but some of the replacements make the gauge read too high or too low.

Bruce

Ok thank you very much

 

[BigBlackChevy77]

I believe that a '77 and '79 should be a direct swap, since by then they both had a voltmeter and an electrical oil pressure gauge. However, you do need to compare the wiring diagrams to be sure.

You will have to buy the gauge sensors for water temp and oil pressure if all you have now is lights. The oil sensor is a little hard to reach because its on the top, rear of the engine near the brake booster, but not that hard to replace. The water sensor is screwed into the driver's side of the block, and the challenge there is to find a sensor with the right resistance profile. There are several sensors that fit and work, but some of the replacements make the gauge read too high or too low.

Bruce

Do by chance know what sensors they are or have a link to the ones I may need ?

 

[75gmck25]

The most accurate temp sensor I've found for my '75 is the Standard Motor Products TS6, which has a "button" type of connector used in '75. There are also classic car online stores that sell what is supposed to be equivalent to the original GM sensor (now discontinued), but they are a lot more expensive.

For the '79 trucks, Rockauto lists the Wells IT1049 temp sensor with 1/2" threads, which means it will screw into the driver's side cylinder head just like stock. This sending unit has a blade/spade type connector, so maybe that's the only signficant difference, but its hard to tell.

Wells 1S6569 or Standard Motor Product TS154 is listed for oil pressure gauge sending unit. However, I've never had to buy the electric sending unit (my gauge is mechanical).

I would use the sensors for the '79 trucks, since they should match the gauges. You have to drain the antifreeze down quite a bit before you replace the temp sender in the head, but its then a fairly simple job. The oil sender is hard to reach because its on the top, back of the engine near the brake booster. The connecting threads are smaller and more fragile, so be careful when you are threading the sensor in.

I think your truck has a hot air choke, so the oil pressure sending unit only has a single function. On newer trucks with an electric choke they sometimes ran the choke power through the oil pressure sending unit so that the choke would only be powered if there was oil pressure (engine is running).

Bruce

 

[BigBlackChevy77]

The most accurate temp sensor I've found for my '75 is the Standard Motor Products TS6, which has a "button" type of connector used in '75. There are also classic car online stores that sell what is supposed to be equivalent to the original GM sensor (now discontinued), but they are a lot more expensive.

For the '79 trucks, Rockauto lists the Wells IT1049 temp sensor with 1/2" threads, which means it will screw into the driver's side cylinder head just like stock. This sending unit has a blade/spade type connector, so maybe that's the only signficant difference, but its hard to tell.

Wells 1S6569 or Standard Motor Product TS154 is listed for oil pressure gauge sending unit. However, I've never had to buy the electric sending unit (my gauge is mechanical).

I would use the sensors for the '79 trucks, since they should match the gauges. You have to drain the antifreeze down quite a bit before you replace the temp sender in the head, but its then a fairly simple job. The oil sender is hard to reach because its on the top, back of the engine near the brake booster. The connecting threads are smaller and more fragile, so be careful when you are threading the sensor in.

I think your truck has a hot air choke, so the oil pressure sending unit only has a single function. On newer trucks with an electric choke they sometimes ran the choke power through the oil pressure sending unit so that the choke would only be powered if there was oil pressure (engine is running).

Bruce

Wow thank you for the detailed response sir

 

[Green79Scottsdale]

Also when going from “idiot lights”, like you have, to gauges, there is a good chance you will have to re-pin the plug that goes into the back of the cluster. All it is, is moving locations of wires. Get a wiring schematic for a 79 and compare the two setups. I have one for my 79, and can look at it tomorrow.

 

[BigBlackChevy77]

Also when going from “idiot lights”, like you have, to gauges, there is a good chance you will have to re-pin the plug that goes into the back of the cluster. All it is, is moving locations of wires. Get a wiring schematic for a 79 and compare the two setups. I have one for my 79, and can look at it tomorrow.

Ok that would make some sense thank you

 

[bucket]

'77 still used the mechanical oil pressure gauge.

 

[Green79Scottsdale]

Ok that would make some sense thank you

Your welcome. I kinda forgot about this. I am pretty sure the wiring diagram is somewhere on this site to download.

'77 still used the mechanical oil pressure gauge.

I couldn't remember when the change over for that was. That is a change that may be worth the effort, imo. No more oil line into the cab.

 

[bucket]

Yeah, if going from idiot lights, no gauge cluster will be a direct swap anyway. But a '79 cluster is different than a '77, which is the only reason I brought it up.

 

[idahovette]

What's the difference in clusters from what years to what years?

 

[75gmck25]

Here are some articles that may have useful info. Most of them also have links to other articles. Its going to take some reading to get a full picture.

http://67-72chevytrucks.com/vboard/showthread.php?t=535828

http://67-72chevytrucks.com/vboard/showthread.php?t=652976

http://forum.73-87chevytrucks.com/smforum/index.php?topic=28070.0

https://www.gmsquarebody.com/threads/gauge-cluster-teardown-and-rebuild-beware-pic-heavy.6035/

Bruce

 

[idahovette]

Wow, that's really pretty helpful. Thanks Bruce!!!

 

[Matt69olds]

I have done several idiot light to gauge on Olds 442 and other A body cars. I don’t know if square body trucks are wired the same, but there is a extra green wire that come off the temp wire to the idiot light. The other end of the green wire goes to the ignition switch. Assuming you haven’t torn your truck apart, if you slowly turn the key, somewhere after the “run” position, and before the “crank position, the temp light may light. If so, you may want to cut the green/yellow tracer (I think) at the ignition switch. Otherwise, the temp gauge will peg full hot every time you start the truck. It should work normally once you release the key, but I’m not sure if the needle slamming full tilt at every startup will damage it over time.