OK, it's right at 18-19" "now" and no dropping. Engine rebuilt in 2009 with all new components but we've persistently had problems with the timing along with a multitude of other problems including carburetors, fuel pumps, what have you. Everything new or refurbished including all the basics like tanks, lines, fittings, electricals, etc. I don't know how it is possible, but in checking through the many notes over the past two years, I see where I have had the timing set at 4 BTDC at least two or three times to only come back later (as the case this week) and find that it has changed. Some kind of a gremlin. This week I found the timing mark to be above the pointer maybe 10+ degrees when viewed with the timing light (cannot recall at the moment if that's advanced or retarded). But oddly enough it fired up and idled very smoothly but would choke down and back fire under load (I think that's characteristic of retarded but not sure). That's when one more time again I had to play with the adjustment slot holes.