Mechanical 6CTA magnetic tach sender wiring

[1969Roamer46]

Hi.

The mechanical B/C  wiring diagram in Tony’s Tips doesn’t include the magnetic tach sender wiring. I’ve got cable-driven tachs on the 1969 Chris Craft Roamer 46 I’m doing a complete refit on, but I recently installed throttle cables in preparation for splashing the boat next month (first time since the PO hauled the boat and left it in Purgatory Row back in 1985!). I also installed an Accusync twin engine synchronizer, which needs a tach signal.

Fortunately, my 6CTAs came with both tach cable drives and the magnetic tach senders on the bellhousing that weren’t attached to the wiring harness when I got the engines. The Accusync schematic indicates there should be a common ground circuit for the mag senders and a signal wire from each.

My question is, which of the wires on these mag senders is ground and which is signal?

Thx

Q

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[1969Roamer46]

I tried to edit the post above but when I hit ‘submit’ I got a page telling me “Sorry, you have been blocked You are unable to access sbmar.com”

Anyway, the additional info I was going to provide is that my mag tach senders have three wires coming out of them–black, red, and green. Presumably black is ground and red and green are signal. If so, should I use the same wires from each sender? Does it matter which one I use?

Thx

Q

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