Gauge questions

[Steve HHI]

I sent the gauges for my ‘68 1600 out for some work. I spoke with the restoration people and they had the following questions for me;

What’s the ohm output ranges on the temp and fuel gauges?

The tac seems to be running 2X their bench gauge, is there some sort of reduction gearing in the system for the tac that would cause it to read twice as high as the “normal” tac?

Thanks in advance.

[todd lorber]

Regarding the tach, I believe the tack cable is driven off of the distributor. At least it is on the 2 liter. The dizzy turns at 1/2 the rpm of the crank, so maybe that is why?

[notoptoy]

^Ding Ding! That is correct of all Roadster Tachs, they run off the distributor which as Todd points out, turns at 1/2 the crank speed.

[Linda]

I wonder if they hooked up the speedo cable instead of the tach cable. Seems they were asking about the oil temp guages which run off the guage VR but does not affect the tach.....
Tell them to trace the cable from the dizzy to the tach.
Or are they just bench testing the tach somehow?
Linda

[redroadster]

I'd say they want the gauge ohms so they can rewind the coils and check when it reads the prescribed setting to cut the wire there ...some gauges have tiny marks showing the wire gauge and #of wraps
Usually you check with a 5000 k range , some where less than that ....they can carefully unwrap and measure the length they may want to know the sender ohms at the fuel level it is at to calibrate