4 cyl tach vs. 6 cyl?

[JayRamb]

I have a 4 cyl tach. Why wouldn't that fit in the gauges for the 258 6 cyl? I am thinkning the stamping is just for assembly line folks. Appears that the plug in is the same for the car

[GRONK]

A 4cyl tach won't read properly on a 6cyl engine unless it has a 4-6-8 switch on the back (some do)  Other than that, they all hook up the same way.

[Jurjen]

Here is some more info:
http://forums.amceaglenest.com/index.php?topic=36015.msg288381#msg288381

[JayRamb]

Thanks guys. I will need to put that aside.

[captspillane]

I have personally broken at least 6 factory tachometers that were barely working when I got them. I have six or eight other tacs that were already broken when I got the car. I don't have a single one that still works. They are total junk and a complete waste of time.  

I have figured out how to install a 4.0 Jeep Cherokee Tachometer into our dash. I will post pictures once I finish it. Those are reliable and I do think it will look nice and factory correct when I finish with it.

The gist is that the metal on the face of the tach has to be trimmed down to fit. The actual mechanism is considerably smaller than the entire face and it will fit our dash housing once properly trimmed. Right from the start you have to cut off the little lip that angles forward from the rest of the face. The scale itself does not need to be altered. I took an Eagle quartz clock out and seperated the front of the plastic from the rest of the unit. I scribed an arc using a lid from a jar, and then a straight line at the bottom, and then continued to scribe until the shape was removed from the plastic. The plastic got set over the trimmed aluminum tach face and holes drilled to match the holes for the alignment pins. The aluminum face was then trimmed further on the bottom and sides.  On the back of the unit are three screws that also serve as input connections. The input wires connect directly to those screws.

[El Matador]

I've looked at those Cherokee tachs numerous times while roaming the junkyard, and wondered if they could be adapted to our cars.  I'll have to pick up one or two next time I'm there, and experiment a bit.

As for the original tachs, I guess I'm one of the lucky ones.  After 25 years and 358,000 km (222,000 miles), the one in my '86 is still working fine.

[thereverendbill]

if you are intersted in selling the 4cyl tach please send me a PM.  best of luck with your project (I think there is a writeup around that someone used an aftermarket tach in the dash and used the factory face)

[JayRamb]

My buddy claimed the 4 cyl tach otherwise I would've offered it to you!

[thereverendbill]

My buddy claimed the 4 cyl tach otherwise I would've offered it to you!

not a problem as long as it gets some use

[mick]

There is always this option.  I still need to buy one for Rat Rod to go from the stock YJ 6cyl tach to the 500 Caddy.


http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=127/category_id=287/home_id=59/mode=prod/prd127.htm