Speed gauge calibration?

[MHunter]

Does the speedometer need to be calibrated? I did my first drive on a highway and the speed showing was definitely wrong, by half.

[Steve_D]

If it is the standard factory speedo then you should have a setting to dial into the gauge. In my build manual (which may be out of date) the figure is 6400 if you have the sender and trigger wheel on the drive shaft. I have no idea how you input the setting as I've not used those gauges.

Any other make of gauge will also have some form of setting system so see the makers instruction.

Final setting is easy to do these days by just comparing against a satnav.

Steve

[SchimmS]

If everything`s set up correctly it could also be a wrong dip switch setting in the instrument. I think the switches have to be set for a 4 cylinder engine.
It all depends on what type of setup you`re running - if it`s an LS series engine the speed output from the ECU gives 4000 ppm (pulses per mile) with a 40 tooth ring.