86 tach with 88 driveline and EFI

[4eyedblind]

I've finished building my 86 coupe with all 88 GT underneath. I can't get the factory v6 tach to read right. It's wired directly off the negative side of the coil and it reads high on every setting. V6 is closest. 4 and 8 read even higher off. Is there something I am missing here in my understanding?

[ford pwr]

Hey from up north,
nice to see the 4 eye driving under it's own power after the transplant and to a person who is keeping it in its current glory.
I couldn't get mine to work either in my 86.

[4eyedblind]

Kinda wondering if I need a tach adapter or resistor inline or what to get reasonable accuracy? The tach worked fine on the v6 when I got the car....

[4-barrel Mike]

4-, 6-, and 8-cylinder tachs are not interchangeable. The exception is some(?) 6k tachs have a small rotary switch for 4-6-8. If you can't find one of those, you'll need to get an 8-cylinder tach.

Mike

[4eyedblind]

That's what I have, the original 4-6-8 tach. None of the settings result in a display even close to correct. My problem is how to fix that. It worked with the original V6 and I now have that tach wired directly to the switched, negative side of the coil.

[RazorbackGT]

What shape is your printed ribbon circuit in? I know after I replaced mine everything worked perfect.

[4eyedblind]

Excellent. The car only had 78,000 miles on it when I ripped it's original powertrain out and, it did work properly before, when the v6 was in.