Thread: Dumb question...tachos and timing lights

Hi
You will have no problem calibrating the tacho with the optical tachometer from Ebay. you will need two people though. basically you run engine to say 2000 rpm on the VDO and have friend take reading on Crankshaft then tweak the adjustment in the side of the VDO up or down till it reads OK Some tachos have two adjustments, one for gain and one for slope. it is best to choose 2 speeds for testing and average the error. ie it is probably not linear so set for say 2500 rpm so it is a bit out at 1000 and 3000 but as close as possible in the working section of the guage. i got mine within 50rpm from 700 up to 3200.

Tachos on dashboards are never calibrated in the true sense of the word and really offer a good guide at best. But I am very happy to have it instead of the clock!

See my post in this thread for more info.
http://www.aulro.com/afvb/showthread...ght=tachometer

james

If you have an ordinary timing light and a petrol engine car with a tacho, you can use that to calibrate your tdi's tacho. Mark a white line on your tdi crankshaft pulley, then park the two vehicles close together. Connect the timing light to the petrol engine and raise the rpm on that to say, 1000rpm. Aim the timing light at the tdi's pulley and progressively increse the idle until the white line appears stationary. At that point the rpm on the tdi and the petrol engine match, so you can adjust the tacho accordingly.

It works, but life's a lot easier with an optical tacho.

Paul