Hey guys i bought a 2888 autometer tach today and plan to install it on my 82 chevette 1.8L n/a engine. Thus far ive found that its got 12 poles (from what i can tell in the GM service manual pictures) on the alternator and plan to measure the circumfrence of the crank and alt pulleys to get the drive ratio.
What im wondering is how all this would come into play when calibrating the tach. As far as i can tell all i have to do is turn a screw left or right to get the proper reading.

Heres a copy of instructions. http://www.autometer.com/productPDF/608.pdf

Any help would be graeatly apperciated :)

i have a diesel tach too on my truck but strangly it dont work. anyways, from the instructions that mine had it said :rev the truck to redline and line up the tach reading with the underhood sticker. So im guessing thats how you do it. on your instructions it says do it at highway cruising speed whatever that might be