Sun tach help

[phat rat]

I just bought this one and need some help in hooking it up as I've never seen one like this. It has two terminals on the back that say INPUT. Below are pics of it plus the box and part number.

[Fat Cat]

You need a transmitter for that tach. On a v-8 you would use part number EB-9A which is 12 volt, 8 cylinder. I can tell you from experience that on a car with electronic ignition a Sun transmitter and tach does not offer reliable readings. I had a factory Sun tach in my 63 GMC and at idle or high revs (above 4k) it was inaccurate.

[phat rat]

Frank, I'm beginning to wonder if someone switched boxes. I agree it doesn't hook up like a normal one piece. Which is what the box seems to be for. But why do both terminals say INPUT instead of one being + and the other -  like this one? I have the correct transmitter so I'll have to check it out I guess.

[Fat Cat]

Hard telling without knowing more about that particular unit. I seem to recall there being something wierd about the one that was in the factory dash for my 63.  It was quite a bit different than the one I ended up installing.

[39deluxe]

Here is an SST70 I have had since '64 or so. The EB-9A transmitter has 4 terminals marked (left to right) Grd, Dist, -, +. The back of the tack is like the 90 in the above picture with a + terminal and an unmarked terminal that I assume is the minus.

The transmitter runs off of an uncommon mercury battery, not 12v from the car. The big screw covers a small adjusting screw that steadies the needle. The black screw on the face of the meter adjusts the needle to zero.

I don't have any idea why your tach in the top picture has 2 + terminals. I seem to remember some oddball truck units from back in the early '60s. I'll bet there is someone around that specializes in repair of these old units that knows what the deal is.

Tom

[39deluxe]

Face

[39deluxe]

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