260hp I/o expectations

[spareparts]

start by checking the engine over good. Check the engine compression, look at or change the plugs, check the wires, cap and rotor. Once you feel the engine is sound, check the ration of the drive(should be on the side of the upper unit). It should be a 1.5-1. I'd say you should be running a 19 pitch prop, or even a 21p prop. A 350 should make that V fly, I'd guess in the 50 mph range turning a 21 p 4600 rpm

[smokeonthewater]

the FIRST step is to get rid of the old gas.... it won't run at full potential... with less energy per gallon you can be running lean as it won't be able to use up the oxygen available which can cause high cylinder temps and detonation and also it can cause a buildup in the engine which is most often noticed by sticking a valve open and smacking it with a piston

Notice I said GET RID OF and not MIX FRESH WITH... 10 gallons of bad gas plus 50 gallons of fresh gas equals 60 gallons of bad gas..... Kick the dirt, cry a little, and pump it all out..... Abuse a $100 lawn mower engine with it instead of a $2000 boat motor