Author Topic: Tack Conversion Kit Question  (Read 1267 times)

Offline clovis73k10

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Tack Conversion Kit Question
« on: October 26, 2021, 02:02:15 AM »
This has already probably been asked and answered, but don't see where it might be so I'll ask as a new question like the site suggests.....  My K10 is a 73.....but the   tach conversion kit says they are only for 78 and beyond.... does anybody know why the 73-77 are not desirable and/or compatible with the conversion kit???  If I try to do use this kit with a 73 I'm I shooting myself in the foot??  I will be redoing the ENTIRE electrical system with a HEI ignition which is tach compatible/has a tach plug on it along with   trucks full electrical replacement bumper to bumper.  Any help is appriceiated

Bryan

Offline dusterdude

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Re: Tack Conversion Kit Question
« Reply #1 on: October 26, 2021, 05:28:26 AM »
I would think a)the tach wont fit your cluster or b)you need the 78 distributor


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Offline Geezer77GMC

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Re: Tack Conversion Kit Question
« Reply #2 on: October 26, 2021, 08:19:26 AM »
The tach kit supplies a circuit board for an electrical oil pressure gauge, early trucks were equiped with a mechanical gauge.

Offline JohnnyPopper

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Re: Tack Conversion Kit Question
« Reply #3 on: October 27, 2021, 07:21:24 AM »
Is your current distributor an HEI? I believe '73 is when GM converted from points to HEI.

If so you have a Tach signal pin.

I don't think you need to change out your entire wire harness just to add in a Tach.

Or are you upgrading your entire cluster?

If not, you can stay with the mechanical oil pressure setup.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline bigben5054

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Re: Tack Conversion Kit Question
« Reply #4 on: October 27, 2021, 09:51:28 AM »
It has to do with the printed circuit.  A new circuit comes with the kit because that is what re-routes the fuel gauge wire(s) from the big pod on the right to the little pod on the lower left.  What Geezer says about the oil pressure gauge may be true - I am not confirming or denying.  But another - perhaps bigger issue - is that presumably, you are currently wired for ammeter but the circuit in the kit is for a voltmeter system.  I don't think the two are interchangeable and may pose a fire hazard if you try. 

Offline clovis73k10

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Re: Tack Conversion Kit Question
« Reply #5 on: October 27, 2021, 05:16:57 PM »
Thanks for the advice guys; boy do I need it.

The tach kit comes with the tach and the cluster box both (from   anyway) so fitting couldn't possibly be a problem (unless the new cluster box will not fit in the dash's sheet metal hole on the 73-77, maybe that's the issue)

As for how things are currently wired; well, nothing is wired, I've already yanked out ALL the original 73 wiring ... the   bumper to bumper wiring system should give me (at least I think so) the opportunity to wire however the opportune way to wire is basically from scratch (of course I have no clue what that is lol)

I'll have to look on   truck and see if there is a conversion for the 350 to put in a digital oil pressure; something like that would solve the new circuit board issue

I took another look at the diagrams that  's bumper to bumper wiring system shows...has LOTS of ways to wire for different years that the kit can service when it comes to the instrument panel.... I would suppose (once again there I go assuming) that a person can 'play' with the wiring set-up and not necessarily stay true to a 73 wiring wise when using  's wiring kit that spans various years.l

HEI distributor (bought at O'Rileys Auto about three years ago) very not OEM LOL ...  this 73 originally had points and a coil and all that stuff.

The possibility of an electrical fire after all is said and done I hadn't considered and now is weighing on me, and I can't shake the idea that there is some reason the powers that be don't have 73-77 as at least possible to add this tach kit.  I'm so over my head with this stuff!!!

I've been told that the Tulare area (about 50 miles from me) is the squarebody capitol of the universe.............any chance one of you guys that are giving me my much needed advice are in that area and maybe could be talked into working with me on this overwhelming garage project  :)  :)  :)

Offline bigben5054

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Re: Tack Conversion Kit Question
« Reply #6 on: October 28, 2021, 09:59:34 AM »
Keep in mind these kits are made and marketed essentially as plug-and-play.  Replace the parts you have with the parts they supply and good to go.  They are not going to go into the rabbit hole of all the various other years/models the kit might fit, if you make further modifications with parts that are not included in the kit you are buying.

Physically fitting is not the issue.  It will fit.

The issue stems from the wiring.  But sounds like you have a clean slate to work with.  I've never completely re-wired one of these trucks.  But my guess would be that if your full wiring harness works for 78-79, and it has the capability and instructions for how to wire for different gauge configurations, you can make it work.

Lastly, the forum rules say you aren't supposed to reference other companies, so that's why your posts get edited.  In case you were wondering.