TOPIC: 67 Merc 650 4cyl-Aqua Meter tach wiring?

My Shell Lake Tempest has Aqua Meter gauges and the speedo checks out right on by GPS.

I'm trying to reprop and need a working tach, I do not trust the cheap micro tach I have.

The 65HP Merc has thunderbolt ignition, the tach has 1 red and 1 black coming out the back on one side and 1 larger grey wire (almost looks like coax) coming out the other.

It has the white merControl and the tach hook up looks some thing like this (1=) 3 female.

I was told to change the location of the brown wire on the motor but she runs good right now and I'm not sure I want to open a can of worms before the show on the 20th. The wires on the motor look to be behind a front cover and would need a bit of work to expose.

Any help would be greatly appreciated, Gene

I am no mechanic, but I could at least bring my Merc Manual to the show for you to look through the wiring diagrams.

Thanks Mark, Bob has the wiring schematics on his I pad. I just do not want to mess anything up and not have her running for the 20th.

Understandable. I have the same thing...tach in hand, but I have not studied enough to do the installation. I think the prop I have may be too small causing it to over-rev at WOT. I will need to just cruise it until I know more. I just have never run without a tach to best keep things in check and best prop for application.

you will need either a special tach for the lightning energizer or a tach that runs off the rectifier for the charging system which is better and cheaper and easier to find.

Dave, Are you saying I can not use the original Aqua meter tach? I realy like the look of those gauges.

Mark, My problem seems to be the opposite of yours. My prop is a 13 pitch and it's huge. She is very slow out of the hole and does not sound wound out at WOT. Gene

if your original was for a mag it wont work. if it was for a was for your ignition it will so I don't know what you have.
look on the back for a ## and look it up and see what it will work on.

OK I'll check it out tomorrow.
Thanks, Gene

Gene,
My tach has one of these on the back to work with the ignition on my '69 650. Its pretty easy to wire in.



-Brian

Thanks Brian, I have it ordered.