My 91 idles a bit choppy but drives good and has no ping on wot - i have owned it for a year and daily drive often . I use 87 gas . I noticed a mark scratched at base of distributor and another mark scratched on the manifold area - I am guessing this is a reference point on where the other owner set the timing . The damper marker is dirty so I would have to clean that off to read dashes . I do not have a timing light either . My engine runs hot in summer heat ( could be many things , but I made sure flow thru rad is good , coolant circulates strong , and fan , clutch and shrowd work good ) this summer I plan to run only water and maybe a wetting agent with corrosion protection . My question is if I pull spout connector off and loosen the bolt and rotate distributor ccw - how much do you actually move it to drop 2 degrees - is it about a 1/4” ? I figure i could always go back to original scratch marks where it was. I know the proper way would be to mark the damper with time light process , but ultimately I will be turning the distributor anyway and I am curious how much do you turn it to get a small change ?