We’ve had a bunch of requests from catalog customers in the past few weeks for a longer tach cable. Seems a bunch of folks are having trouble getting the tach cable to reach from the dashboard to the generator. We never had that problem before, so I thought this post might help explain how to properly set-up your tach so that the stock cable will reach.
First, the proper location for the tachometer is in the inboard (large instrument) hole in the dash. This effectively shortens the cable run. So start by making sure your speedo is outboard and tach inboard. If your tach is closest to the fuel gauge, your cable might not reach the generator.
Secondly, you need to make sure you have the tach cable coming through the correct hole in the firewall. In the photo above, you can see tach cable, wiper motor wires and windshield washer hose, from left to right, filling the three holes outboard of the battery. Make sure your tach cable is in the proper hole, or your cable might not reach.
In the photo below, the blue car has the wiper wires and tach cable reversed (the washer bottle is missing and that hole in the firewall is plugged). This routing will put undue kinks in the tach cable behind the instrument, and make it more likely that your gauge will be jumpy. Mr. cable likes a nice fair curve.
Speaking of a nice curve, the cable also needs to run aft of the heater box and forward of the battery. Note green “Boyd” below, where the cable makes a nice gradual “S” from the dashboard to the generator, to the eyelet at the solenoid, to the tach drive on the generator. The blue car (above) has the the cable routed incorrectly.
Now look at the blue car below which is done incorrectly, and you can see the cable running in front of the heater box and beneath the heater valve. To make the 90 degree bend to the tach drive, the cable has to make a much tighter radius, which stresses everything. You should be able to see the nice gradual curve made by the cable in the photo above.
The mechanical tach cable, drive and tachometer has to be set-up right if you want it to work reliably. Make sure you have the routing correct (or you can try one of our new electronic tachometers if you want to go with a more modern electronic system-click here to check those out).