Okey dokey, here’s the results! Took the old gal out for some exercise after finishing up the 12v Sunpro Super Tach II installation. I put the little 2 5/8” face model in, so it would fit in between the instrument clusters on the AD and not block out the view.
I made up a plate that bolts to a spare hole in the dash bracket above the mast jacket. Mounted on the plate is a 6v to 12v, 6amp booster cube, a four position terminal strip and a on/off spst toggle switch. I picked up 6v to the toggle off the rear Bat. buss on the light switch. From the toggle switch I’m wired to the booster through a fuse. Out of the booster comes my 12v to feed the terminal strip buss. I wired the power for the tack and its light to the 12v buss so the light is on all of the time. Signal wire goes directly to the distributor side terminal, which is the negative terminal of the coil. And that’s all there is to it.
I had already bought the booster cube because I am sliding a CD player under the dash that can be quickly remove when I want. The CD player will be wired to the remaining slots on the terminal strip and the booster will supply 12v to the Tach and the CD player.
Before I installed the tach I just had to see what made it tick so I opened it up for a look-see. With 12v applied I found a 1w resistor right off the power lead that was dropping a little over 7v, which tells me that the SS circuit probably runs off of 4.5 or 5volts. So, it is possible to change one of them into a 6v tach simply by changing a ten-cent resistor or two. Now what the value of the new resistor should be and how to recalibrate the unit, well, that’s going to take an engineer, I’m just a mechanic.
So for now, I have a Tach or Tunes at the flick of a switch and when she’s gonna have to sit a spell I’ll just flick the power supply to off.
Happy motoring
Denny Graham
Sandwich, IL
Last edited by Denny Graham; 04/28/2008 3:40 AM.
