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Gauge Gurus, Step Inside Please

B

Busted Knuckles

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I have a '77 K-5 with the gas gauge cluster. I want to buy a tach cluster and put it in my truck. I'd rather go with an electric oil pressure gauge, don't care for hot oil in my truck. I understand that Chevy went to an electric oil pressure gauge in '78. Did all the dash wiring harnesses have all the wiring for all gauges and just not use some, or were the wiring harnesses specific to the gauge cluster that was to go in the truck? What schematics are available for my truck?
Any advice would be appreciated!
By the way, it looks like the Blazer is getting a Gen 6 454 all forged hydraulic roller engine and a very well built 700R4, that's why I need the tach!
 
OK, not going to be easy.

PCB is going to be different. '77 cluster housing is likely not the same, which means you'd want to use the newer housing. Which means the PCB from the newer housing, which is not set up for the small fuel gauge, which means you'd need to wire the fuel gauge separately.

One option might be to get one of the heavier than one ton truck clusters that I believe had the fuel gauge as part of the tach.
 
Are the main PCB connections the same - can I find the wires I need on the truck harness side of that connector and go from there?
 
Yes, I don't believe the '73-91 instrument panel connector ever changed in physical shape. Of course the wiring did, but that's easy to change around.

The easiest thing I can think of, is use the newer cluster housing and PCB, and just jumper the fuel gauge wiring to the small location. Depending on if a clock was used those years, there is likely already a ground and 12V at that location, but if they are ganged up with the lights and what not, you'll have to run each of the three wires separately to the small location.

In my experience the earlier clusters like yours are all set up to bolt a tach in, the plastic just isn't cut out right for it's connector, and thats an easy fix since the tach wiring is completely separate of the IP connector. (although you could probably get power and ground from the PCB/IP connector for it)
 
Since I'm too lazy to look it up, could someone tell me what the first year an OD auto tranny was offered? I'm switching the original 350 for a well built 700R4 and I'd like the gauge indicator to have the OD on the selector.
 
Thanks!
I found a set from the same year as my truck but part of the housing is broken. How difficult is it to add the tach and fuel gauge to my existing setup?
 
I just put a 79 gauge cluster into my 74. The housing is a little different for the gauges and the circuit board is different. You can cut holes and run new wires for the electric gauges. I actually rewired the truck with a painless kit at the same time so when I made the plug for the instrument panel I just put all the wires in it for a 79 and up. Just be aware though i did all this to get a tach and got it all put together and the freaking tach doesnt work right. I wasn't happy.
 
If you are saying you've got a tach cluster with a broken housing, the swap is easy. Remove the PCB and put it on yours, move the gauges, and your done. :)

You will still of course want to compare the PCB to yours, just to make sure there wasn't a running change that year in wiring. I have a buddy that fried a tach cluster by just plugging it into a different year truck. :(
 
I know my tach didnt come with plugs. But it says on the back of it what terminal is what. I wired it all up exactly like it says and it works but is way off. And when the truck is off it sits at 5k. Im thinking maybe the needle is off or something.
 
OK, that sounds easy enough.
There's a guy in Florida that restores Corvette guages. He can change redline, speedo max, and quite a few other things. Do y'all know of anyone who does that for these?
 
You've gotta be careful you don't get a 6 cylinder tach. 25% fast on a V8. :)

99.999999% of the time the needles won't be off, something else is wrong. Needles break too easily, most of the time people end up breaking the gauge attempting it. With as few tachs are out there, the likelihood of someone removing one and moving it is slim to none.

When off it doesn't matter where it sits, as long as it goes to 0 with the key on/engine off.
 
Now that assumes you've got good power and ground to the gauge as well.

Double check those, make sure both are good.

BTW, the tach connectors seem to be be fairly similar in GM setups, Camaro connectors (very common with tachs obviously) should fit.
 
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