These tach's can be restored with a little effort. A gentleman at SAOCA
published
an excellent "How To" article, published on their site.
Recently he calibrated mine; earlier he calibrated my Alpine tach and for
both
provided a report comparing actual vs gauge through the rpm band. Both were
set to dead on.
http://www.sunbeamalpine.org/index.php?categoryid=82&p2_articleid=28
On Aug 17, 2010, at 1:24 AM, Tod Brown wrote:
> There was a time, before there were the modern conversions for our
> tachs, that some folks in TE/AE (I believe one involved was Tom Ehrhart)
> made measurements on the accuracy of our "state of the art"
> transistorized tachs and found that they were quite questionable. This
> indicates that the normal deterioration of the old electronics in the
> tach is the main cause of the inaccuracy, not anything to do with the
> use of Pertronix ignitions. IIRC, you can often rehab an old tach by
> replacing the big capacitor on the circuit board or, if that failed,
> replacing the transistors which could be found very cheaply at Radio
> Shack. However, nowadays it is a Good Idea to convert to Pertronix or
> some other more reliable ignition system in our cars, for obvious
> reasons. You can also replace the coil with a new Pertronix and do away
> with the ballast resistor at the same time. It also makes sense to me
> to have the old electronics in the tach replaced with a new circuit
> board. Tom Hall and Theo Smit have designed such an improvement and can
> make the conversion for you. It cost me $165 a couple of years ago and
> I expect the calibration will outlive me. If you want to preserve the
> original tach for posterity, pack it up and put it away and use
> another. Most of the Smiths tachs are interchangeable as the mechanical
> parts are pretty standard. If you add a new circuit board, it can be
> calibrated for your setup. I am using a tach out of a Series IV Alpine
> with the new circuit board installed. The lettering is identical to the
> stock MkI/IA tach except for the notation (in small letters) that
> indicates "4 cyl, positive earth" which hardly anyone can read,
> especially Jim Armstrong. It has the added benefit of having a higher
> red line. Use the tach out of a Series V Alpine if you have a MkII
> Tiger. You can even have the face redone with new lettering by Paul
> Breuhan if you wish, so no one will be the wiser.
>
> Tod
> B382002384LRXFE
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