So I picked up one of these gauge panels years ago and never used it. Digging around my gauge collection for a project and the tach might useful… if I can figure out how to wire it. It has the light plug and one wire as seen in the picture. Now, I’m not a boat person but I’ve hooked up a lot of automotive tachs before and I’m failing to understand how this can work. Is this the signal lead? Is there no 12v on? Is this some outboard motor only deal that I've yet to learn about? Is there a way to make these work on a car or does everyone just set it away in a drawer to be forgotten about?
Similar one on eBay right now. eBay item number:364071657446 It shows only a one wire hook up but the back of the tach is marked 8 CYL. So my guess it should be made to work in an automotive application. The question still remains, how?
I'm an old boat guy, and I believe these work off a sensor that watches the flywheel? Pretty sure? Maybe? Lol.... I worked mostly on inboards so didn't deal with many mercs, but I'm pretty sure that's the deal. Sensor that counts off the flywheel....
I guess my question is why? Why not just use a car tach? Just cause ya can do something doesn't mean you should.
Well he has the tach, going to have to run some wires anyways, if it’s just a pickup sensor and bracket it might be less expensive ? I’ve no idea why a made in USA tach costs these days, I’m still recycling my Sun Super tachs. Lol
I already have it, I wouldn't have to spend money if I can use it, plus it looks cool. Seems like a few other people have them laying around, too.
When I wanted a tach for my stock flathead most of everything out there was 8 or 10 K. Took me a while to find a 4K VDO tach. That said I would have run the tach no questions asked if it would have worked with my flathead.
I'd call Autometer auto gauges to see if this would work to sense crank revolutions. https://www.autometer.com/magnetic-tach-probe.html
This may adapt to your situation: https://www.holley.com/blog/post/everything_you_need_to_know_about_msd_crank_trigger_systems/
Some info here that may be useful: https://www.forabodiesonly.com/mopar/threads/using-crank-position-sensor-for-tach-signal.219124/
I have several of those panels with gauges. They all came out of boats with Mercruiser 4cyl. Chev II engines in them. Somehow in you installation, you will probably need to determine what type engine it was hooked to. As someone else pointed out, the tach should be marked as to what engine it was fitted to. Good luck and have fun.
Lots of crank trigger parts here for various engines: https://innovatorswest.com/parts/crank-trigger/
I'm still trying to narrow down what years it what used so I can go hunt down a wiring diagram. I did find a parts list showing the panel being used 1963-1966 for the Merc 110, which was the Chevy 153 CI four banger. Curiously, it looks like Mercruiser was still putting Chevy 409s into boats as late as 1966 as the Mercruiser 310, at least according to their factory literature. They were replaced by the 396 in cars mid '65.
Mercruiser225 was a Chevy 327 from 1963-1966. Curiously the V8 tach has a different part number 33234 as opposed to the 4 banger part number 32831. The tach was probably different depending on the engine. Just guessing but maybe the single wire is the signal and it grounds through the gauge panel body? Would it need a separate 12v lead?
Rear view of similar tach head: https://autopartsobsolete.com/64691...ER-TACHOMETER-GAUGE-TACH-PRE-70-s-MARINE.html
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