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Yes I'd want someone who has physically seen the # on a VC187 like my parts house saw 10L on a VC 188 since the printed material seems to be so bogus/inconsistant. I think the ones (Prestolite?) with the hex nipple can be unscrewed & washers added to slow the start of the curve, not sure how to bring it in earlier (weaker spring?). All the ones with the regular nipple I've ever checked the slope (not the total which is the # on the arm)) can be adjusted with a 3/32" allen wrench.


Yes the older style can, like those used on dual point dist used shims to adjust the rate. The ones like the VC187 adjust with an allen key.

I actually bought on today. It is stamped 9L meaning it has 18 degrees crank advance. I actually have a Sun 400 distributor machine that I just rebuilt. It has a vacuum pump with a regulator and I mapped the curve from 10" hg to 20" hg. This was done with two and a half turns counter clockwise on the adjuster. I'll try to post it shortly. As I recall it was about 7 degrees advance at 17"



Here is the graph of the advance VS vacuum