VDO tachometer question

[YerDugliness]

I just took possession of a fairly well built roadster kit car, and the tachometer is WAAAY off--it appears to be reading at twice the actual RPM's. My speed calculator says the engine should be turning 2050 RPM's at 70 MPH, but the tach reads 4100 RPM's.

I managed to crawl under the dash and get a look at the back of the tach, hoping for a "switch" that would change the calibration for 4, 6, or 8 cylinder engines, but no such luck. What I did find was 4 lugs for wires, one for a "hot", one for the lighting on the gauge, and what looks like TWO grounding lugs.

Is it possible that this tach might read correctly if I were to switch the ground connection from the current grounding lug to the other? It's the only thing I can figure out......anyone have any ideas?

Thanks in advance for whatever help you can provide!

Dugly

[Curt C.]

There should be some little pins that will recalibrate the tach to 4, 6, and 8. Go here

http://www.springfieldstreetrod.com/..._DIAGRAM_C.jpg