Black on Black 1967 Camaro L78 124377N212598

[jbtech]

Originally Posted by scuncio

How were you able to adjust the tach needle?

Jason's advice and photo from post 270:

Originally Posted by SuperNovaSS

There is a potentiometer on the back of the tach behind this sticker to adjust the rpm reading. Just be careful, the potentiometer can be fragile after all these decades.


Jason

I used a very small flathead screwdriver and with the power off I ever so slightly turned the what I'm assuming is the potentiometer screw counter clockwise. I retested and repeated until it was accurate to my liking. I read that it's possible to cause a short if the screwdriver touches the housing during adjustment which is why I did mine with the power off. It was tricky and I couldn't even see inside the opening for the potentiometer but I as I gently turned the screwdriver with the tips of my fingers I waited for it to fall into the slot, Once in the slot I felt a resistance as I turned the screwdriver. Luckily it only needed 2 adjustments. After adjustment I replaced the painters tape that I used to cover the hole.
With all of that said the tach needle itself when the car is off rests about 100-200rpm too high, but since my readings were accurate from 2000-7000rpm after adjustment it was fine by me.