68 XR-7 with MSD tach help

Cougar Community Classic Cougar Maintenance Restoration and Repair
1

I’m helping another of our club members with problems with his 68 XR-7 X code cat. He’s not much interested in what makes it work, so, unfortunately, he has taken the car to various mechanics and shops and they haven’t done much to make the car better. So I’m going through it to figure out what was done and how to make it work.
The car ended up with a Holley Sniper EFI after he took it in for a tuneup. That’s not necessarily bad as the car starts right up cold and runs quite nice now. When they put in the EFI they also put in a MSD distributor and digital 6A (PN 6201) box, but of coarse they couldn’t get the tach to work, so they installed a MSD tach adapter. Problem is that the tach still doesn’t work. I believe that they hooked it up wrong, but I’m not exactly sure. In the tach adapter instructions it has a couple of ways to install it based on if the system is voltage triggered (tach Originally hooked to coil negative) or current triggered (tach originally hooked to coil positive). So is a 68 XR-7 voltage or current triggered?

2FE325A8-7A3C-4D6B-A3DB-AFC4500510B8.jpeg
2FE325A8-7A3C-4D6B-A3DB-AFC4500510B8.jpeg800×600 221 KB

Thanks for any and all help.

2

Current triggered.

3

Awesome, thanks Bill.
Nothing in the manual about that.

4

All FLM products of that era used current-sensing tachs; the tachs must be in-line between the ignition and the + side of the coil. Ford was the only one of the big 3 who used current-sensing tachs, IIRC.

5

Best way to fix is have Rocketman convert the tach to modern technology with three wires.

6

Thanks guys.
I was looking at the three wire tachs from Rocketman. I’ll have to consult with the car owner first. He previously paid for the other MSD items, so I’m sure his preference will be to get it operational with what is here rather than buying more parts.

7

They work fine with the MSD Tach adapter if it is wired per the MSD instructions. My GT-E was wired that way for 20+ years.

8

Now I just have to make sure that they did it right, or make it right.