Tachometer Question

I just purchased a tachometer for my 1975 15hp Evinrude. It is an aftermarket tach that works by sensing the spark through a wire wrapped around the spark plug wire and then runs back to the unit. My question is can I shorten the wire that runs from the tach to the spark plug wire. I have about 18 inches more then I need. I could always bundle and tie it but like to limit the clutter under the cowl if possible.
Thanks for any help.

You can but it will throw of the reading a little(depending on model, probably negligible). They are calibrated for a certain length wire. Instead of bundling under the cowl, bundle it on the back side of the tach. You are under the dash less often than under the cowl.

Thank you!!