Re: tips on getting more horsepower on 4.3 merc
Simple cheap easy mods, for a bit more HP:
1) Put "Mobil one" full synthetic oil in, of the recommended weight (maybe 10-30W?) I have yet to find an over the counter oil that is slicker, I now use it in All my vehicles, (but I haven't yet tried Royal Purple, or Redline racing oil due to their price).
2) Put synthetic marine gear oil in your drive (the proper consistancy)
3) With the engine warmed up, & idling, adjust your idle mixture screws out usually counterclockwise to the highest idle speed you can get, and leave it there, you might use a bit more gas this way, but it's the best setting for power.
4) Make sure your flame arrestor is clean, I'd take it off, & clean it with a good spray carb cleaner, then let it dry & put it back on. I think K&N makes a low restriction flame arrestor if you want to go that way.
5) Make sure you have good metallic core suppression spark plug wires on there, and new spark plugs for a healthy spark, a new high perf coil would help (MSD/Accel).
6) Make sure you have the right prop for the load, under, or overpropping, will defeat any mods, and wear your engine out fast.
6) wax, or polish your boat bottom if you can, this always worked for me, despite some naysayers here
Aside from these, you'll need to get into the engine mechanically if you need more HP, Bond-O had the best suggestion!
