Dizzy without notch on the rim

yeah i dont have a notch on my dizzy for timing, so how do i go about getting my tune right.
this is a right pain in the arse.
cant use a test light as i need voltage from the alt for the compufire (dis ix) to work.

anyone help out please😠

Hi

Number 3 will be retarded, you will be able to find which one is number 3 by using a timing light, then its easy to find number 1. Remember the firing order is 1 4 3 2 or 1 2 3 4 backwards.

Steve