[McGillicuddy]

ESD, it is an '83 inline-6, and I appreciate the the insight because this is my first Merc. Right now the bottom of my anti-cav. plate is at 1-1/4" above the keel so I think that's about right. I'm not cavitating or ventilating. Not sure what you mean about the motor not liking too much rpm...

Here's Fr. Franks earlier comment regarding this motor.

"The inline 6 "Tower of Power" Mercury motors are fantastic motors and nearly bulletproof when cared for, but there are some idiosyncrasies to worry about. Never, Never run these motors between 6200 and 6900 rpms - they'll self-destruct quickly from engine harmonics. (Believe it or not, running higher rpms than that is okay up to about 9000 rpms, as long as you run the right fuel-oil mix. Mercury Marine used to race these motors turning 8000 to 9000 rpms, making over 225 hp out of the 115/125 hp motors, and over 250 out of the inline 150 motors.) But these motors love to run at 5400 to 6000 rpms. I have owned no less than 9 inline 6 Mercury motors in my life, and still have an '86 115 in the shed.

I suggest you be very careful with the fuel/oil mixture, based upon your average rpms. If you run mostly over 4800, I suggest a 40:1 mix rather than 50:1 mix, that'll keep your top cylinder better lubed. However, if you run mostly below 4800, stay with the 50:1, or your spark plugs will need periodic cleaning."

Are you in agreement with this, or what do you consider "a lot of rpm"? Merc manual's range is 5000-5500 for the 115 hp.

I'm at 5000 rpm WOT now with an avg. fishing load. I think that a 15" pitch will get me to 5300 rpm and hopefully 5500 rpm, but I doubt the 5500, based on the fact I only increased 150 rpms per inch of decreased pitch.

Am I OK running this 17 pitch for a while or is it putting undue stress on my motor?