Thread: boat tachometer in car?

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i found this thing at a yard sale.

after trying to research it on line it seems that it was used on 8 cylinder engines.

i don't have a sender (or whatever it is called)

i wonder if it would work in the 27 Chevy? ford 302 engine

in a worst case scenario would i just burn the tach up?

or would i cause damage to other electrical components of the car?

the problem is airguide made tachs for many types of engines and they all look the same.
2-4-6 and 8 cylinder
there is supposed to be a number on the back to tell what it is for.
mine has no number.
so i guess i will hook it up.
if it fries it will go on the wall of shame.

The number of cylinders is just the scale factor - it counts the pulses from the coil, and depending on how it's scaled it divides by 2, 4, 6 or 8 to equal one revolution. Ground one of the posts on your tach and hook a lead to your negative post on the coil and touch it to the other post with the engine running. It will either be right or off by a proportional scale factor, 1/4, 1/2 or 3/4 speed.

More importantly Billy-is do you trust that tach on your prized 302??.

If it's the type that take a sender chances are you WILL smoke it if you hook it up directly to the coil (ask me how I know )

I think that one needs the sender to work. If it didn't it would have at least 3 studs on the back......power, ground, and signal from the coil. I see only 2. Tachs are cheap enough (Super Tach II goes for about $ 40 new) so I see no reason to try to jury rig this one to work and maybe burn up a coil or ignition module that would cost more to replace.

Don

Originally Posted by Itoldyouso

I think that one needs the sender to work. If it didn't it would have at least 3 studs on the back......power, ground, and signal from the coil. I see only 2. Tachs are cheap enough (Super Tach II goes for about $ 40 new) so I see no reason to try to jury rig this one to work and maybe burn up a coil or ignition module that would cost more to replace.

Don

Don, I think you're right based on the old AirGuide wiring diagram. They seem to have two models, one for magneto and one for battery ignition, but both have matched senders.
http://www.classicboatwork.com/class...0Style%201.pdf

Originally Posted by Louey

That's the same link I posted rspears. Plus, it's called a transmitter, not a sender. It converts the signal into pulses. Anyway, there it is. The price on those old units are up there also.

Not sure why Louey, but your post did not appear before I started my reply even though the time tags show twenty one minutes between them. Had I read your reply I would not have bothered posting, but it doesn't really matter anyway, nor does the nomenclature for the device between the coil and the display - transmitter and sender are just different words for the same function, a transducer that receives a signal, massages it and then passes it on for use by another device. The important thing is that billy knows it won't work by itself, and like Mike P says, is it really worth it anyway??

I like calling it a sender better..........I can't spell transmitter.

Don

thats why i ask you guys.
you know and i dont!

thanks fellas
it looks great hanging on the wall in my living room.
too bad i cant use it.
such a cool looking tach....