<VV> Tachometer

[Bill Elliott]

Without going into a full discussion of the history of tachometers, _most_ tachs do not require sending units (though some did).  Most modern tachs (mid-
60's forward) only require a single wire hooked up to the negative side of the coil. As long as the tach does not require a sending unit (like a Sun) or is 
inductive (like some Smiths), it will pretty much read with the single wire to the coil.

Now the other bit you need to know is that factory tachs (like the one from your Volvo) are set up for a specific number of cylinders while after market tachs 
generally have a switch for 4, 6, or 8 cylinders. It is difficult ($$) to modify a tach that was designed for a set numbers of cylinders to match another, so 
unless that Volvo was a 164 or a more modern one with the PRV6, it is likely not a good candidate for a Corvair. (In the earlier tachs with the sending unit, 
the tach was universal and the sending unit matched the number of cylinders...)

Corsa tachs are available for well under $100 (since you can buy a whole Corsa dash complete for less) Otherwise, an aftermarket tach (with the selector 
switch) is the next best way to go. It will not look as stock, but will work. (I have a large aftermarket tach new in the box I'll sell you for my cost if you want to 
go that route.... but these are readily available on Ebay or a number of sources.) If your car is really a Corsa, it should have the wire to the coil  already in 
the harness and you'd need only to attach the stock (or any aftermarket) tach to it... but I'm equally sure that somebody online here would have a decent 
stock tach for you as well... no need for a "rebuilt" as the units rarely have issues... they seem to work or not work....

Bill Elliott



>My '65 corsa was lacking a tachometer when I bought it, for reasons unknown 
>to the previous owner and me. I'd like to replace this gauge, but was a 
>little confused by the offerings of Clark's. The catalog lists three 
>tachometers that would be compatible with my car, one of them an original 
>rebuilt, the other two are aftermarket items, both the same size and from 
>the same company. The price for one of the after market units was about 140 
>dollars, the same as the price of the original rebuilt. However, the third 
>option was listed as "complete with sending unit" and was only seventy five 
>dollars. I was thinking of buying this third option, but then I found a 
>really good deal on a tach that was designed for a foreign car. I was 
>wondering if this tachometer (for a Volvo) would work with a corvair, and 
>whether I actually need to buy a sending unit. How can I tell if I have a 
>sending unit already in my car? Thanks.