[tekheavy]

My hood tach on my '67 seems a bit off. Seems to be reading too low. Are there any adjustment on them? And if so, can it be adjusted while mounted on the car or will I have to take it off the hood?

[einstein]

I recall when Padgett was repairing tachs, he used a graphite pencil to apply some graphite to a spot on the circuit board to tune the resistance. He said the factory reading was generally 200 RPMs off to read higher than actual engine speed. I do not recall where or how exactly but he had a meter reading the resistance and I saw it change to his desired spec.

This was close to 40 years ago and he's been gone 3 + years already. I did not commit the technical details to memory, obviously.

Hopefully someone else here has this knowledge.

And maybe this question would get more engagement in the Electrical forum.

[70GS455]

Yes, the aftermarket ones usually include a potentiometer. You will have to remove the tach and unseal the top and bottom

[tekheavy]

Originally Posted by 70GS455

Yes, the aftermarket ones usually include a potentiometer. You will have to remove the tach and unseal the top and bottom

Ok, thanks. I will give it a shot before I put the car away for the season.