1991 Peterbilt calibration 700 series speedometer

Didn't you go through this @blairandgretchen?

 

Try this. Always write down where you started in case it all goes wrong.

 

Try calling Powl's 717-898-2552. They are in Lancaster, PA they might be able to help you.

 

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Hey @Bulldog trucker -

Click that link above to take you to a previous thread - read what @mtoo posted, and go from there.

Read whatever I had said about it, I think I started somewhere close and went 6-7 numbers up at a time, drove to the next exit, had the dash half apart, pulled the speedo, clicked the switches and took off again - set cruise at 60 on a GPS and matched it.

Took me couple of times but now its dead nuts.

I went from 3.70 to 3.55 with 24.5 LP - 1995 379 Pete.

Hope it helps and good luck.

 

Here is the chart for 700 series

https://www.ametekvis.com/-/media/ametekvis/download/technical-support/700_series_speedometer_caibration_switch_settings.pdf

 

Yup.
Without any tricky math - the chart @mtoo has will work with the magnetic speed sensor you have.

Post your findings here to help others.

Cheers.