Year One Repro Tach Problem

sbbuick · Apr 4, 2005

Dan Healey said:

But the resistor and the Zenor should be in series connection between either the neg side of the coil, or the MSD tach connection, and the pos tach lead.

In other words, the pos tach lead connects to the bottom of the Z diode as drawn (or output), and the resistor connects to the Z diode as drawn, and for HEI, the other side of the resistor connects to the neg side of the coil (the input), and for MSD the connections, it goes to the tach connection on the MSD box. Correct me if I'm wrong on the connections guys. The Zenor should work just fine, it will block the a/c current being induced from the high engergy output of the spark plug wires, and it will clamp an output voltage. I assume you would want to purchase the diode with 12-15 DCv range. :bglasses:
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OK Thanks!

I think I've got you. I am using an HEI with an internal coil, though. I'll have to look at my set up and figure out which wire is the neg side of the coil.

LARRY70GS · Apr 4, 2005

sbbuick said:

OK Thanks!

I think I've got you. I am using an HEI with an internal coil, though. I'll have to look at my set up and figure out which wire is the neg side of the coil.
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If you have an original coil cover, it's labelled. C-, Grd, B+. The - side of the coil is on the same side as the tach connection. The + side is the main ignition feed.

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Year One Repro Tach Problem

sbbuick My driving scares people!

LARRY70GS a.k.a. "THE WIZARD" Staff Member

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