Reply With Quoteif it has a ignition box or msd multi-spark type system, the tach wire hooks to the ignition box not the coil.i've ran into tachs that don't work with msd ignitions but they were old p.o.s. tachs too.
So i put a new MSD ready to run distributor in my boat ('81 ford 460 engine) hooked straight up to the coil (Petronix Ignitor II). The motor runs fine, but the tach is reading low, it should be around 4500 rpm, but it shows 2900 when i'm floored. I believe the gauge is the original tach in the boat (Medallion Instruments) when the boat had points. There are 4 setting dial switch setting on the back of it (its set to 4), I don't know what any of them mean. Of course, there's no documentation and I haven't found any on the internet for it. The owner before me put a Pertronics Electronic Ignition Kit in the boat, the problem is that I don't know that tach was ever right. Is it possible the older tach might not be compatible with an electronic ignition?
if it has a ignition box or msd multi-spark type system, the tach wire hooks to the ignition box not the coil.i've ran into tachs that don't work with msd ignitions but they were old p.o.s. tachs too.
I'm not using an ignition box, just distributor hooked up the coil.. Tach on the neg (-) side of the coil..
So i put a new MSD ready to run distributor in my boat ('81 ford 460 engine) hooked straight up to the coil (Petronix Ignitor II). The motor runs fine, but the tach is reading low, it should be around 4500 rpm, but it shows 2900 when i'm floored. I believe the gauge is the original tach in the boat (Medallion Instruments) when the boat had points. There are 4 setting dial switch setting on the back of it (its set to 4), I don't know what any of them mean. Of course, there's no documentation and I haven't found any on the internet for it. The owner before me put a Pertronics Electronic Ignition Kit in the boat, the problem is that I don't know that tach was ever right. Is it possible the older tach might not be compatible with an electronic ignition?
The selector switch on the back is most likely there to set the number of cylinders in the motor that the tach is attached to.
A friend of mine recently tried to use the old tach in his boat after doing some ignition upgrades and couldn't get it to work right no matter what he did. Dropped a new one in and it worked right away.
Rob
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