Tachometer, applications and wiring

Hi,

Wasn't sure where to post this, but as I think this tachometer was only used in medium duty trucks, I put my questions here.

Recently I got a vintage IH tachometer to use in one of my trucks. The IH part number is 556 906 C91. It was manufactured by Motorola Automotive Products, model no. 7ST23047H A, 12 volts, s/n 8443 0036.
Unfortunately it did not come with any directions. And after accessing the IH shop manuals CTS-2000ABC, CTS-2001 and CTS-2300, this is the total said about their electric tachometer in these three shop manuals:

" The electric tachometer is a two-unit combination consisting of transmitter and tachometer head. The head is mounted on the instrument panel and the transmitter on engine side of dash. The tachometer is equipped with a magnet, rugged double bridge construction, sensitive jeweled movement to assure longer life and greater accuracy (with 2% of full scale). The electric tachometer receives electrical impulses from the distributor through the transmitter and records the r.p.m. in this manner. "

My questions are the following:
-1- Is this the tachometer referred to in these shop manuals?
-2- Which IH applications used this tachometer?
-3- Does this tachometer require a transmitter between the distributor and gauge head? If so, what is the part number of that transmitter? And the part number of the gauge light sockets that go into it?
-4- How do I wire this tachometer (and transmitter)? What wire goes where? The tach has a pink, yellow, white and brown wire going to its connector.

It does have a circuit board in it that I don't want to fry by connecting the wires incorrectly. If necessary, I can take it apart and photograph the circuit board if that will help to answer this last question. I know electronics can fry in a fraction of a second so I especially want to get its hookup correct before applying any power.

Google searches have been no help with the four questions above. And I could not find it in any of the wiring diagrams in those 3 shop manuals.

Thanks.
Steve


.

.

That looks like a tach out of a 9670 or 9300 and is used with a mag pick-up on the flywheel ring gear. I don't think it was made by Motorola, but Prestolite, they have since merged (I think). Scott will better be able to shed some light with the parts numbers.
I don't think you can make it work off a coil (spark ign).
Duh, helps if I look at the sticker...says Motorola right on it. My Mototrola tach has a flat four blade connector (all 4 in a row) on the back, the later one in my '89 has the plug yours has. So I would say that is from at least '85 because my '84 is different.

The IH pn tells me might be from the "Necessories" catalog,so it would be an "add-on" item OR it's for a much later model than either of yours (the face tells me that,the box is pre Navistar too btw). Since it requires a transmitter it's likely for a diesel anyway.
It's not in the later Loadstar MT's,they used cable driven tachs,so did the Transtar. Looks like the one in the 9370 I drove for awhile.

A little Google'ing I found a transmitter with a very close IH pn,no application listed though.
http://www.ebay.com/itm/Navistar-Intern ... 1336931962

Yeah, that is 3/4x16 tpi and threads into the bellhouseing on heavy truck diesels.
it looks like it has a cover for access to dip switches to calibrate for different engine/ring gear combos. Which would make it a replacement or aftermarket install as all mine are fix calibration for original install, no way to re calibrate for a different engine or ring gear size.

Hi,
Thank you both for your replies. Your help is appreciated. Clearly this tach is not what I expected, but I'm learning. Fortunately I found someone on one of the diesel forums who wants this, so it's going to go to them.

But ... now I have another NOS IH tach, but it's mechanically driven. I also found someone with a nos cable to go from the distributor to this tach. So now I'm looking for the distributor itself. How would I find or what would the Delco part number be for a tach drive distributor that will work in a IH 304 V8? I think they were only used in the Loadstar and bigger trucks. And will 266, 345 and 392 tach drive distributors also work in a 304?

I can supply the IH part numbers if needed but the local auto parts store clerk's computer does not show any cross-over to a Delco part number.
Thanks.
Steve

I seriously doubt you'll find a Delco with a tach drive but,ya never know so post the pn's. I'm there's more than one # so be concise with the app. or post all the pages from the book including the index pertaining to the SV8 dists.The main difference with SV8 dists. is usually the vac. advance unit which I'd need to see the book for confirmation.
The only other option is to find a Holley dist. since they were used for a longer period and would likely be easier to find.
That isn't a bad thing,the Delco's are coveted (especially the cast iron ones) by many and would be easy to sell or trade/barter with. I have an idea there too.

I looked up the Holley w/tach drive in the 2 later LS books and at least one pn might be available thru the NSN system,one also shows on Machinery Trader.
I'll post the info if you want it.

I'd hold off on that cable,matter of fact you'd be better off buying a kit or having one made (I have sources) because they're not "one size fits all". If the guy has an IH pn for it,post it and I'll check it out. You may also need drive tip(s),which the kit I have in mind comes with.

I seriously doubt you'll find a Delco with a tach drive but,ya never know

I would have never guessed Delco distributors would be hard to get. I ass-umed they would be like alternators - every vehicle needs one of some type, so I expected one could order a remanufactured unit of any configuration from most any parts store.

so post the pn's. I'm there's more than one # so be concise with the app. or post all the pages from the book including the index pertaining to the SV8 dists.The main difference with SV8 dists. is usually the vac. advance unit which I'd need to see the book for confirmation.

Wow, thank you so much!
The first page of the pdf link below is the index page that pertains to 304 V8 distributors. The remaining 4 pages are the only two Delco distributors that have tach drive. The girl at the stationary store scanned the pages in reverse order, so you must start at the bottom page for Fig. 08-037, then the next page up continues the parts for that fig number, then the next page up is Fig 08-126 then the next page up, immediately below the index page, is the remainder of the parts for Fig. 08-126. The very bottom page of the pdf is blank.

The only other option is to find a Holley dist. since they were used for a longer period and would likely be easier to find.

I'm not a tune-up expert and prefer Delco's only because I'm more familiar with them. I will consider a Holley as a last resort after I feel every possible Delco source has been exhausted.

That isn't a bad thing,the Delco's are coveted (especially the cast iron ones) by many and would be easy to sell or trade/barter with. I have an idea there too.

Unbelievable - I never would have guessed there would be any demand for an old, cast iron points-type Delco distributor. Perhaps I need to start calling around and see if I can find any Loadstar-type truck/bus junk yards.

I looked up the Holley w/tach drive in the 2 later LS books and at least one pn might be available thru the NSN system,one also shows on Machinery Trader.
I'll post the info if you want it.

Don't post it yet, but keep that info handy as I might need it before I'm finished with this project.

I'd hold off on that cable,matter of fact you'd be better off buying a kit or having one made (I have sources) because they're not "one size fits all". If the guy has an IH pn for it,post it and I'll check it out. You may also need drive tip(s),which the kit I have in mind comes with.

Wow, I had no idea such a kit is or was ever available. Yes, I'd definitely prefer to make my own. What a learning experience all this is for me! Thank you!
Steve
.
http://www.ihpartsamerica.com/forums/at ... butors.pdf
.
(I still can't figure out the proper way to post a pdf file here)

Well Steve,just as I suspected the pn's for the dist. you'd like to find are obsolete. The only things I got search results for were the Remy site listing them as obsolete and as references for tune-up parts.
The only suggestion I have for finding a DR unit with tach drive is to contact Jeff Ismail at IH Parts America. Mike Maybem remans their dists. and may just have one,he put one in one of his trucks I saw when I read the entire thread below.
http://www.ihpartsamerica.com/forums/ig ... ation.html
This is worth reading!

If they have one,maybe you can strike a deal and use yours in the transaction? If you read that thread you have a better idea of why the DR units are so desirable(?).

As for the Holley units,at least one pn appears to be available NOS and is one of the #'s listed in the index for Fig.08-128 (359220C91). In the MT-127 that # is listed as a production pn and 291260C94 as the service pn. Can you post the pages for it? Would like to see 08-102 as well.

I have everything in a file,links included for the Holley units I looked up already.

Here are the links I have for speedo/tach cables.
http://www.texasindustrialelectric.com/speedo.asp

http://www.transmissioncenter.org/speedometer_cable.htm
The kit I mentioned is near the bottom, CA108. IH went to kits like it in the 70's,there were (are?) a few pn's depending on core diameter and OA cable length. The IH kit came with only one ferrule already crimped on the housing,the other was "screwed" on (LH thrd. IIRC) after everything was cut to length. I made quite a few for over the counter customers,not hard to do. One end of the core is squared,the other would get the needed tip crimped on (tool supplied). The square end is where the "floating" tip goes (see "Compensating Tips for .150 Inner Core" in 1st link) which "snap" into the retainer inside the ferrule for that end. As I recall tach drive tips are the tanged type on at least the dist. end and square? at the tach head.

I looked up and checked the old IH pn for the per made cable assy.,it is 54" long.
https://www.google.com/?gws_rd=ssl#q=59766R91+cable
It might be available? It's possible a floating tip would needed? I don't remember what they looked like end wise.

Another custom cable vendor;
http://www.speedometersolutions.com/spe ... _cable.htm

Btw, as far as I know PDF's always appear as links,which I believe is because you need a reader/viewer app. like Adobe to open them. I can't recall ever seeing a PDF being fully visible except as a screen shot and those are pretty useless.

Its a little bit different but I got my spedo cable for my Loadstar from Advanced Auto Parts. I went in with my old cable and they called their cable supplier matched up the ends and had me a brand new one in 3 days. Real reasonable as well, under $20 IIRC. So you local auto parts store may be able to help unless they are lazy or a clueless counter jockey. If not Scottso has mentioned several good options.