Anyone retro-fit a factory tach to their Mustang?

[zookeeper]

A freind has an original tach for a '67-'68 Mustang at a reasonable price. I'd like to buy it, but I'm a bit concerned about getting it to work on my car. I know that factory tachs are not wired like aftermarket tachs, but rather wired in series with the coil. My question is, if I use a Pertronix ignition, can I still use that tach? I don't want to go through the headache of buying a GT harness, since my original harness is in perfect shape, so any advice is appreciated.

 

[mr-fixit]

The factory harness for cars with the tach is totally different then a non tach car, along with the other guages and sending units. The biggest problem with this conversion is that the plug going into the instrument cluster is different for tach and non tach cars. I think Mustang Monthly once did an article on the conversion, but it is not a plug and go deal. I don't know about the factory tachs working with electronic ignitions, but I know it also can be made to work. Check out Tachman.com for info on making it work with the Pertronix.

 

[fvike]

I've done it on my '69 Mustang. I found a how-to at www.boss302.com. I don't know how similar the '69 wiring is to the '67-'68s...

 

[SNAKEPILOT]

The gauge cluster is different too. You will need to get a 67-68 tach dash to fit the tachometer. They are not easy to find and are not cheap.

 

[67CoupeDriva]

I'm in the process. There are three basic changes that you need (in addition to the actual hardware including the tach and the cluster back which is different as mentioned above).

1 - we'll start with the easy job. You lose the oil pressure gauge and get an idiot light. So you have to change the sending unit right by the oil filter. You will also have to hack the wiring on the back of the cluster to be sure that the oil press wiring gets to the light.

2 - The actual tach. This is a little more tricky but not too bad. It has two leads which are, in theory, wired in series to the coil wire coming out of the ignition switch. I have had a little trouble getting this right and I'm not sure if it's because of the resister wire (yes I cut the one that says do not cut) or if it's my Pertronix ignition.

3 - Hardest (most wiring). You also lose the ammeter. This requires a fair bit of rewiring from the alternator through the regulator, and includes wiring some resistors in on the back of the cluster (more cluster harness hacking). Of course you could just not use the idiot light but if I'm installing a factory tach, I want it to work like the factory.

There was an article about how to do all three of those things in Mustang Monthly a while back I think, but I can't remember which issue (I want to say 10/99 or 11/99, but that may not be right).

Good luck! If all else fails buy the tach and sell it on eBay for a profit then buy yourself a custom cluster or something.

 

[zookeeper]

Thanks for the info, guys. Since I'm building a Shelby clone, I plan to use a ammeter and oil pressure guage in a gauge pod like the '67 Shelbys used. The guage housing itself is available through Tony Branda, and Stewart Warner sells guages that look period-correct and use modern sending units, so hopefully that will help me avoid cutting my stock harness. Also, SnakePilot, I'm not sure what you mean by the cluster being different, all '67-'68 Mustangs use the same bezel, doesn't the tach attach to the rear of the bezel, or is there something else in the back I need? I think I'm going to buy it and worry about making it work later. After all I'm too far along money-wise in this car to worry about saving money now! Thanks again, everyone!

 

[Edbert]

I'm in the process.

Snip...

That's pretty much it, cut the pink one that says do not cut and you're done. Drove one like that for 15 years.