MountainBen

I'm in my second first gen vehicle. I have boost and pyro guages already installed and want a Tachometer. Any advice on best way to link to shaft revolutions? Perhaps some kind of external sensor with a magnet mounted on the front belt wheel? I don't think there is a mechanical option, like a worm drive for a true mechanical tach. Any tips would help. Thanks. Looks like a great site. I've done a bunch with KZrider, a motor cycle forum site. These forums have really changed my world.

OneBigDoofus

There are mechanical tachs but they may not clear the automotive style fan assemblys

Free89W350

The big question is what year are you working on. Fill out your sig to let us know what you have and aid us in the correct way to point you in. The early first gens, I believe 89 90 91 don't have a "factory" tach option but the later ones do and there is a plug under the column that you can use to operate a tach. There have been a couple of threads recently about the installation of a tach. Try to do a search for "tach" and also check out the sticky at the top of the page there might also be something in there about it but I'm not 100% sure.

Oh yeah WELCOME TO THE SITE!!!!!!!!!!

MountainBen

I have a '93 W 250 with just under 200K miles. If there is a factory set up on this motor for a tach, that would be ideal. I did check the sticky at the top and it looked like a description of a factory plug for a tach might exist in the cab compartment. Does that mean the connection to the motor revolutions (tach plug) is already within or about the motor and I might just need the instrument end? Thanks for the welcome and I will continue searching.

Chrisreyn

Ben, your 93 will have a factory tach wiring harness in place, ending at the tach plug under the dash. Basically, if you had a OEM tach, you would simply mount it, plug it in, and away you'd go...
Now, the problem with that is that the factory tachs are becoming increasingly rare and are very high $$$ if you find one...
There are several options for installing an aftermarket tach for a lot less $$ and there is a great "how-to" thread in the "Stickey" at the top of the forum page.

Hope this helps!
If you click on "USER CP" on the left side of the bar at the upper part of the page, you can fill your vehicle info into your signature. It will appear in your posts automatically, so folks can see what vehicle and mods you have.. makes it easier to answer questions for ya!
and Welcome Aboard!!!!

MountainBen

OK, but what I don't get is wether that stock harness is connected to a sensor in the motor and is already there delivering an rpm signal to the harness. I was planning on mounting an aftermarket tachometer on top of the dash, pedestal style, over near the pillar. Does the '93 come with a stock sensor built in which simply needs to be completed in one way or another in the chassis cab?

Free89W350

Should be a plug and go deal. I do believe that they are ready to go and you just need to hook the tach in.

Chrisreyn

Ben, I guess it would depend on thestyle of tach you buy as to wether you can just splice it into the factory harness.

these two threads should answer your question:

Factory Tachometer wiring diagram
https://www.dieseltruckresource.com/...d.php?t=185725
Tach Install
https://www.dieseltruckresource.com/...d.php?t=173561

whereswaldo250

What is that picture of?

OneBigDoofus

Skid mounted 6BT

MountainBen

Thanks everyone. I got the Isspro Tachometer, 3&3/8" #8530M with harness and cup stand. Mounted it to the dash and followed the instructions here to connect it as a plug and play. It works great!