Wiring the tach to the coil?

[jwinkler]

Gentlemen -

While my Hyfire is under the microscope (hopefully) at Mallory, I want to drive the car. I can bypass the box just fine, but it leaves me without a tach signal.

Poking around online, it appears that I could connect the tach input to the negative side of the coil, but I couldn't find explicit instructions to that effect from either Mallory or VDO (I've got the CR factory gauge set).

Before I short something, will this work?

Thanks,

JLW

[dscott]

JLW, what ignition system do you have in the car (dist, control box, coil)? If it's a mallory distributor with the self contained module you can run the tach wire to the coil.
Don

[jwinkler]

Don -

It was Mallory all the way, now just the coil (ProMaster) and distributor (Unilite). With the Hyfire gone, I'm using the bypass plug that apparently lets the Unilite's optical module trigger the coil (is that right?).

Thanks,

JLW

[dscott]

JLW, yep, Unilite will trigger the tach signal. Should work ok.
Don