Replacing the clock with a tach

[txjeeptx]

Excellent writeup with pics, captspillane. I have a car that has an aftemarket tach installed where the factory tach sat. I'll try to get a pic of it.

The pre-1991 XJ(or was it pre-1990?) dash cluster was not computer controlled, whereas the later ones got their driving information from the fuel injection ECU. That means pre-1991 XJ gauges can be used with direct feeds from sensors, like the signal to the tach from the ign coil, or a oil pressure signal from a sending unit.

[Zoro]

The pre-1991 XJ(or was it pre-1990?) dash cluster was not computer controlled, whereas the later ones got their driving information from the fuel injection ECU. That means pre-1991 XJ gauges can be used with direct feeds from sensors, like the signal to the tach from the ign coil, or a oil pressure signal from a sending unit.

Correct! I have a pre '91 tach sitting on my workbench. On the computer board for the tach are hookups for 3 wires like most after market tachs. IIRC ground, positive and the pulse line from the coil and you're good to go. I'll see if I can get a photo.

[captspillane]

The rear of this tach from a 1992 has three inputs as well. I'm installing it along with the entire 1992 fuel injection, so I'm not worried, but I did believe that those were the exact same inputs as the earlier tachs. I thought the only difference was that the pre-1991 speedometers had a mechanical cable and the later ones got their speedo feed after it already went to the computer. If the computer does look at the tach feed, I doubt it modifies it before it reaches the tach itself. Anyone scrutinize this before?

In a few months I'll be able to better describe what I had to do to make it work. If you guys have a picture of a pre-1991 unit and its backside, please post it here.

[GRONK]

Here's the Tach I'm using on Bucket (pronounced Bouquet)



Ignore the extra wires, The tach itself has the standard 3.  This is from a Jag 4.2 and is perfect for the Wag.  I'll do a nice writeup and take lots of pics.

[AMCKen]

Enough for the tach at least. IIRC there's quite a bit of room.  : )

Thanks! Is that a 2" tach?

More like 2.5 I think.

[vangremlin]

Has anyone ever considered a tach from a ford with a 300 inline 6?  Here is a picture of an instrument cluster for an 80-86 F150, its appealing because of the 0-6000 RPM range.  I'm not sure how the size of the tach compares with the Eagle, but you might be able to use the original Eagle face plate and the rpm's would be relatively close.  I think I'll go to the junkyards this weekend and see if I can find one.

[GRONK]

Very nice.  I may invest in one and find out.

[eagleman]

Hey Vangremlin that looks promising. You might be on to something there.

[mr.mindless]

a tach and trip meter sure would be nice, I'm going to keep an eye on this thread..