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factory tach on a 91 burb?

Discussion in 'The Garage' started by ol beater, Jan 19, 2004.

  1. ol beater

    ol beater Registered Member

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    sorry guys, the search is not working. can anyone tell me about installing a factory tach and small fuel guage into a 91 instrument cluster?
     
  2. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    I can't give you a good answer (and you may have already figured it out) but you're going to have to do some creative hacking. The 91 has an electric speedo so neither "shell" that the guages are attached to will interchange with all of the guages.

    I would think the easiest way would be to put the tach in the 91 cluster. You could use a small hole saw to punch a hole in the shell (be careful not to damage the printed circuit) and then snake the tach wires out the back of the cluster. As for the fuel guage you might pull the appropriate wires out of the harness and connect them directly to the guage. I rewired the fuel guage this way on my '80 when I put a tach in it (but I also had the advantage of using the complete tach cluster assembly due to the mech speedo).
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    As John pointed out, the 1991 cluster is going to be different somewhat.

    I haven't pulled apart the one I have, but on all of the NON-electric speedo '81+ clusters I've pulled apart, the mounting provisions for the stock tach are there. You may have to cut the back of the '91 cluster for the conenctor, but it SHOULD still have the mounting tabs.

    I don't know how you are supposed to thread those holes though, with them being this old, the plastic is brittle, and will likely crack when you put screws into it. *If* you can get a tap that matches the screws used from the factory, use it on the mounting points, and that would be your best bet, by far. It may sound anal to use a tap, but I'd hate to break all of those and be SOL without a new housing.

    I did mine without a tap, and still cracked the plastic. Of course, you don't know it's happening until you hear it crack. /forums/images/graemlins/frown.gif
     
  4. BurbinOR

    BurbinOR 3/4 ton status

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    So are y'all saying there was NO factory tach option for '91 like the early years? /forums/images/graemlins/confused.gif
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    It was said awhile back that 1981 was the last year for factory tachs. I can neither confirm nor deny that as fact, but my '85-86 parts manual (nor the '87-88 manual I just picked up) doesn't list a tach at all. It does list all the other gauges, but not the small fuel gauge or tach.
     
  6. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    I agree, 81 is the newest I have actually seen.

    I just went to Dremu's site that has all of the brochures. It's a little hard to read but you can see the tach specifically listed on an 81 truck but on a 90 (91 brochures not up yet) the only thing optional shown is a trip odometer. /forums/images/graemlins/thinking.gif
     
  7. ol beater

    ol beater Registered Member

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    thanks guys,
    I still need to find a tach and maybe I'll use a junk electronic speedo cluster for a trial run if they are cheap enough.
    I'll will post if I should try this stunt.
     
  8. Steve_87K5

    Steve_87K5 1/2 ton status

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    I put a stock GM tach in my '87 cluster.

    Tach by itself is p/n 25054251.

    I had to modify the plastic with dremel tool. But not a big deal. Works off the HEI tach lead and ign switched +12V. The tach lead does bring in ignition noise to stereo and AM radio. This can be fixed though.

    I put a Cyberdyne digital gas gauge in the 4x4 idiot light opening. It still works OK after a few years. (all the other 3 Cyberdyne digital gauges I put in have failed, volts, and 2 temp gauges)
     

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