any one know how to calibrate speedo on 91 n/a 5 speed with out saying to switch tire size, is it possible, search engine hasn't been real helpful

 

Mechanical speedos such as ours can be easily- if not necessarily cheaply- calibrated.

The process involves determining exactly how far off the device is and then building a gear box that is interposed between the transmission and the gauge. This gearset corrects the gauge reading.

Here in Denver is a speedo repair/calibration shop that can do this, there might be one near you.

 

thank you for a real answer i will check around do you know what that might cost

 

I've only done it once, and that was a while ago...seems like it was somewhat north of $200.
This was the same place that calibrated the State Patrol cars, so they may have been more expensive, I really don't know.

You may have other options though.
Ofttimes, the same transmission is used in many different applications and different speedo drive gears are available.
If you know how far off your current setup is, it might be possible to just change the drive gear and get in the ballpark.