I would suggest: (1) setting the initial with "the vac gauge method" (2) get 34-36 total (initial+slots) useing the right slot pair on the FBO plates (I was not aware there is a prob with em). (3) mix/match spring combo so you are just under the pinging point at WOT up thru the gears on your hottest/driest(most likely to ping) day then (4) plug in the can (if used) & adj it with a 3/32 allen so you are just under the ping point under varying RPM/load conditions in everyday driving on your hottest/driest day & there are differenct cans available that the curve starts at different in hg levels (do your homework there) & you can shorten the total as needed (strips of epoxied feeler gauge) & increase it slightly (file notch wider) as needed. Peoples' hearing varies & there is silent ping so give it a slight cushion & you want to be "reasonably" close to that "pinging" line but never over it. & check that it will crank over when hot & if balky use an ign cutout to get it cranking then switch on the ign or retard the initial (1) deg & retry. Those guys who mod dists can get em in the ballpark or even close but every eng is different & dead on needs alot of adjusting/tweaking.
the FBO plates I have are totally screwed up. near as I can figure the slots are set up for .010" movement equaling a degree. this wrong. .0154" is a degree. .010" is close for the vacuum advance degrees. I measured and checked every way from sunday and they're just plain wrong. I did do some measuring and found a way to use some of the slots , but the plate shifts position at full advance that screws up the desired total. first time I got anything with FBO on it that was wrong. waste of $50.
