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So I picked up a "later" tach dash today...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dyeager535, May 24, 2003.

  1. dyeager535

    dyeager535 1 ton status Premium Member

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    So I picked up a \"later\" tach dash today...

    and I'm wondering what year it actually is. The truck was an '87, but various parts inside the truck had been swapped, and there was no factory tach wiring I could find, so I'm not sure what year truck the tach came out of. I know there was/is a thought that '81 was the last tach year, but from doing a search on this board, I noticed post-'81 trucks being parted/sold with factory tachs as well.

    Just wondering what anyyone elses look like thta are that vintage. This one is definitely the "later" font/script(?), I think it was used prior to '81 ('79?) but definitely the same font/script used up until '91. I've got an earlier (early-mid 70's) tach, and that certainly doesn't have the later font/script this one has. Since I don't know the history, and the plastic lens was removed, I can't say for certain the rest of this cluster hasn't been messed with either.

    This one is odd, because it has no "red" or "yellowline" to it, it's solid white. My dad has a similar year tach as well, but it's got a yellow/redline. This isn't one of the industrial truck tach's from C60 or whatever trucks, and it's definitely a gas version, having the connector on back marked "ground/bat/coil"

    Got a decent deal on it, but the housing is broken and its been in the weather. Popped the tach out of it, unfortunately this tach isn't labeled 6 or 8 cylinder, so until I plug it in, I won't know if it works or is the for a V8 or 6.

    Interesting other discovery, apparently my dads '81 (or so) tach is a 6 cylinder model, we though his gearvendors OD just wasn't enough, but its actually reading about 25% faster than the engine can possibly be turning. Not sure if his is marked on the back if its a 6 or 8 cylinder tach, but I've seen that stamp on Camaro tachs.
     
  2. MousePowrd

    MousePowrd 1/2 ton status

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    Re: So I picked up a \"later\" tach dash today...

    Maybe tachs were only avail on four speeds. I have never seen a tach on a late model Blazer. Where would it go?
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: So I picked up a \"later\" tach dash today...

    Tach goes where the big fuel guage goes normally. Fuel becomes the 4th gauge in the small gauge cluster to the left of the speedo...

    Rene
     
  4. m j

    m j 1/2 ton status

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  5. BranndonC

    BranndonC 3/4 ton status

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    Re: So I picked up a \"later\" tach dash today...

    where could someone order that tach/fuel gauge kit?
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: So I picked up a \"later\" tach dash today...

    Gonna go out on a limb and say that you can't buy new replacement tach dashes, at least not factory. Thats why the tach dashes are relatively expensive.

    You'd have to go with something aftermarket, or convert from another application.

    Problem with aftermarket stuff is that it's never a 'bolt in" deal, you'd have to trim the cluster and so on.
     
  7. jjlaughner

    jjlaughner 3/4 ton status

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    Re: So I picked up a \"later\" tach dash today...

    [ QUOTE ]
    where could someone order that tach/fuel gauge kit?

    [/ QUOTE ]

    I had a tach and small fuel gauge in the for sales for two weeks at $35 no takers, but I decided to keep it and try wiring it in anyways /forums/images/graemlins/thumb.gif /forums/images/graemlins/rotfl.gif
    Had a holley TBI for $200 but I may use it now since no one was interested /forums/images/graemlins/grin.gif
     
  8. Re: So I picked up a \"later\" tach dash today...

    jjlaughner,
    Have any pics of the Holley TBI? I might be interested. Let me know.

    Thanks,
    Doug
     
  9. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    Re: So I picked up a \"later\" tach dash today...

    I looked into this a year ago - was told that it wouldn't work on my 91. Wish I remembered why..... /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: So I picked up a \"later\" tach dash today...

    [ QUOTE ]
    I looked into this a year ago - was told that it wouldn't work on my 91. Wish I remembered why

    [/ QUOTE ]

    Dunno, since the tach wiring is seperate, always went where the fuel gauge went, and the fuel gauge/tach mounting never changed AFAIK.
     
  11. mudpuppy89k5

    mudpuppy89k5 Registered Member

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    Re: So I picked up a \"later\" tach dash today...

    A friend and I installed a factory tach/gas gauge set-up in my '89 when it was new. He had worked for GM as a mechanic for a while and got all the parts new from GM for an '81 pick-up. That was a while ago, but as I recall, we had to replace the cluster housing, printed circuit, and a circuit board. We also had to cut a piece off the housing in the truck and glue it to the new housing so that the cruise control would work. It all worked like a charm (still does).

    He later bought a '91 Suburban and planned to change it over as well but found out that GM had changed the plug on the Suburban wiring harness and it would not mate with the cluster. Again, this was a long time ago in a galaxy far, far away, but that's how I remember it.
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: So I picked up a \"later\" tach dash today...

    No, you are right, the printed circuit board and housing are different, but that's all "minor" details. /forums/images/graemlins/smile.gif

    No reason you can't do this on any of the clusters though, I looked last night. The housing needs to be cut out behind where the tach would mount (for the 3 prong seperate wiring connector) and the wiring for the fuel gauge wiring needs re-routed to the location for the stock clock.

    The housing itself though, is cast with the mounting provisions for the tach. There are 3 extra holes underneath where the fuel gauge sits (for anyone following along) which are how the tach "bracket" bolts down.

    The circuit board is different only because it does not have provisions for the large fuel gauge, instead it has the cutout in that area for the tach wiring to pass through, and it has the wiring for the fuel gauge instead routed to the clock location.
     
  13. 88streetblaze

    88streetblaze 1/2 ton status

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    Re: So I picked up a \"later\" tach dash today...

    I have actually bought the plastic housing and printed circuit to do this conversion, but then gm discontenued the tachs before I could get one, probably a good thing since they were ~$350, I did find a 3/4 ton tach that has the fuel gauge in the tach gauge, but that setup is not asetically pleasing. the opening in the back is actually 2 pieces a larger square piece that screws in and has the opening in it for the plug wires..
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: So I picked up a \"later\" tach dash today...

    Ouch. I can imagine they weren't cheap if the tach was that much. /forums/images/graemlins/frown.gif

    That's ok, getting ready to call AC Delco and see if they can get me the circuit board for the tach itself, the one that is physically bolted to the tach. The one I bought doesn't work, I'll have to hook a Camaro circuit board up to it to make sure its not the tach drive itself. I'm fully expecting the circuit board/components on the circuit board to be the problem.

    Wish I could find a description of exactly how GM did these tachs. There has to be at least one "hard" difference between the 6 and 8 cylinder tachs, plus it would be nice to know what each component on the board did.
     

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