So, I know it's many years later, (it's a long story). but here is how it turned (or tuned) out,
I kept the new dist. in the boat with the vacuum and mechanical advance. I was able to pull a load of people and skiiers and it worked just like a car. i could "floor/ wrist" it wot. and...
I have a 350 mercruiser 1989 Marlin inboard skier. 19 ft. 260 hp. Everything runs fine. I've down loaded the stock timing curve, and I can see why my gas time is bad. I do not use wot., I don't go past 27mph. I'm 51 and this is the year for wakeboarding. RPM'S at 2100. Manifolds warm...
