I've searched, and found some old threads about wiring the MSD and tach, most are the non-digital version, and others that do have digital contradict each other, meaning it works for some and not for others, so I'd like a fresh opinion.

Using the example schematic that came in the install instructions seems to create a possible contradiction because it says the gray wire goes to the tach, but it says to connect both of the car's white wires together, and the white wire on the car is the tach signal to the cluster (correct me if that's wrong).

Here's the MSD schematic I am referencing.



So should I connect the car's (tach) white to the gray and only the distributor's white (signal) to the MSD white? Or should I connect the distributor, tach and MSD white wires together?

Some extra info that may or may not matter:
When I bought the car 4 years ago, it had an MSD (analog) box installed. It did not use the tach out spade terminal and while the tach worked, it was certainly inaccurate. So I don't know if it was ever wired correctly in regard to tach operation.

 

When I installed my MSD 6AL about 20 years ago, the tach would bounce all over the place. At that time MSD made a coiled piece that attached to the wire hookup (the tach) for that problem. Can't remember what it was called, but it did cure the tach needle bouncing problem.

 

Thanks. That's what I keep finding is what people did many years ago. That may be why mine wasn't working right with the old one. Did you connect the cluster tach white wire to the msd white wire or to the msd tach connection?

 

Sorry, no idea, since I paid an electrical shop to first install the MSD box and then correct the tach problem. The experts at MSD (at that time) knew of the problem and installing that part was the cure. The part is only 2"x 1 1/2" and I have it mounted on the firewall just behind the Blaster coil.