Saturday, March 19, 2011

Stewart Warner Mechanical tach drive for a ford flathead

Sometimes you just get lucky.

I went to the Long Beach swap meet in January when I was in LA for the Grand National Roadster Show. I went with the purpose of finding a vintage SW mechanical tach drive for a flathead. Believe it or not, the first vendor I went to had exactly what I was looking for at a really low price! I bought it of course.

In case you aren't familar, flatheads are tough to hook a tachometer up to. GM cars had tachs driven off the backs of generators and companies like Mallory made tach drives off distributors for small block Chevies and other engines.

But, with a flathead you had to run an electric tach setup. In the 50's, that wasn't so hard. You went down to Western Auto or SoCal Speed shop and bought a tachometer setup with instructions and you just hooked it up.

Flash forward to today, you would have to find an electric tach, then find the correct sending unit, either one of which might not work and then figure out how to wire it up, or you could buy a SW mechanical drive which mounts on the front of the flathead using two bolts that screw into factory tapped holes in the engine block and then you run a cable to the tachometer on the dash. There is also a small cable that runs from the tach drive to the crank nut.

It's a simple setup and that's why I wanted it. That's why guys in the 40's had them at the dry lakes, it was the easiest way to set it up and at the lakes, it was necessary to know your RPM's for fear that you could blow up a flathead if you revved it to high.

But for some reason, either they didn't survive the constant beating of high RPM's or they got thrown away when OHV engines came in, these mechanical tach drives are rare and usually very expensive.

I'm glad I got this one and it has nice home on the '32. It just needs some more cleaning.

All I need now is SW tachometer, anyone got one for sale???


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