Well time to find some expert advice. I have a 1986 Chaparral with a Alpha One Mercruiser 200 V8 small block in it. Thunderbolt ignition system. I went to do a tune up as I was missing on two cylinders and plugs were 10 years old.....NEW plugs, cap, & rotor were in order. The screws for the old cap would not come off in the boat......so, I had to remove distributor. On the workbench, 3 of the 4 screws snapped off. Decided it would be easier just to update to a newer distributor with an electronic sensor instead of the older style (87-91019A3) ignition sensor. Found a working one on ebay for reasonable price. Installed distributor in engine lining up timing marks and rotor to #1 position of cap. New cap, rotor, & plugs installed. Fired boat up, idles great but no power at throttle up....... almost like no spark advance at all. Is it possible the newer version sensor is not compatible with my ignition module?? I moved timing 10-15 degrees either way by rotating distributor thinking it might be an initial timing set point issue......but don't really see much difference except if you go too far either direction with timing, even the idle dies....which one would expect. I am at a loss.....please HELP. Thanks! Jeff