Weird, My 87 sunbird GT NON turbo (2.0L engine) has 2 notches engraved onto both sides of the distrubutor- one notch on the outer esction , the section you turn clockwise/couterclockwise to set the timing) and one notch on the base. One could line them up and they would touch/when lined up. Is this a factory notch? has to be- I doubt some mechanic from many years past would have engraved these quite deep notches on my car. Why did GM do this?
BTW, currently, the timing is set where the notches do NOT meet. I could change it but I believe the car would run sloppier if they matched.
The factory distributors did not come with any markings for timing the distributor.Our 1st gens use what is called the averageing method.On the RHS is a tan and white line colored wire for timing.You unhook this when timing the car rotating the distributor to set it and then rehook this single terminal round plug.It is close to the strut tower going towards the blower motor.It has been couple of years since I had to retime my ride because I removed my distributor on a intake manifold gasket replacement.I may have to reread my manuals to be super specific.I will say it indicated in my manuals to unhook the 4 plug wire to the distributor when timing but I did not do this.I know that while I know how to do it,and John masson on our 1st gen board knows this as well I do not want to over information you too much.