[v2rocket_aka944]

They do exist but they are rare - I have one such piece for the 16v engine, brand was "Dial a Cam".
It seems they were produced many years ago and then the supply ran out.

It has drilled/tapped holes for 0/1/2/3/4 degrees advanced or retarded and can be adjusted to a new position in about 10 minutes.

I have one of their gears on my 8v engine as well.

If there were a lot of interest it might be worth sending mine off for "reproduction" but I doubt that we could make it very economical.

The stock gear does have some adjustability but I haven't taken the time to measure the range. I think the 928 guys say it might allow 3 degrees in either direction.