Anyone know how to calibrate a 1966 Vacuum gauge in the Oldsmobile to Chevy swap?

[msg]

Ive been doing custom swap and reached the point where the needle gets put on and the gauge. As I test with my refrigerant vacuum pump the needle will go as far as 10 and sometimes beyond. If it reaches close to 15 the needle gets stuck. I have to tap it to return it. Its not binding on the faceplate so I think the gauge needs calibrating because when I dismantled it and pulled the needle off there was slight movement of the coil/spring that had some tension on it originally with the old needle on.

I noticed that when the needle reaches 15 and sticks that the toothed silver arm has extended to the point where the central gear isnt on the toothed silver arm that pivots in the middle. So once the teeth arent on it and it reaches its end it sticks. Ill attach a pic of what i am seeing.

If anyone has dealt with this and has some pointers Id appreciate it.

[Tpo]

I’m bumping this because I have a similar question. I’m close to buying a beater Pontiac or olds gauge and installing it in my gauge panel on my 1960. However, the olds and Pontiac gauges read 0-24” while the correct Chevy truck gauge reads 0-30”. Plus they have different “sweeps” if that is the right term. Sooo, if I simply put a 0-30 overlay on the 0-24 gauge, what’s the deal? In his awesome thread, chevyrestoguy adjusted the needle and stops, but it was unclear if the gauge read and swept accurately afterwards.
I don’t mind keeping the stock Pontiac overlay on the gauge if it means it is more accurate, but those repro overlays sure do look nice.
Thoughts?
Thanks!

[61hawk]

[Tpo]

Thanks Hawk, that looks killer!