rpm questions in and out of water.

[8up]

Hey everyone,<br /><br />It has been awhile since I have posted. My boat is running great. My questions are....we set the idle at 700/800 rpm in the water, in gear. When I flush it at home on the muffs, it idles at 2000 rpm in nuetral. My WOT rpm is about 5600 rpm running 39.4 mph (gps). What rpm should I "cruise" at? My motor is a 1985 140 hp evinrude on a 1976 Wellcraft V-20. Does this all sound Okay? Thanks, you guys have helped me learn alot about my engine and enabled me to get out and enjoy the Chesapeake Bay with confidence.

 

[rickdb1boat]

Re: rpm questions in and out of water.

It all sounds OK, except for the 2000 RPM idle on the muffs. Should be a little higher(1000)in neutral, but not 2000. Check to make sure your linkage is adjusted corectly and returning to the idle stop. Also, make sure that the timer base is fully retarding at idle. cruising at about 4000 RPM's will save some gas, but whatever you are comfortable with is fine as long as you are on plane..

 

[reeldutch]

Re: rpm questions in and out of water.

my 110 evi idles 1500 on muffs sometimes 1700 bud not 2000. check the tach.<br /><br />reeldutch

 

[Solittle]

Re: rpm questions in and out of water.

Your most efficient cruise will be around 5000 rpm (WOT less %10). However most motors have a sweet spot that you can hear - and that may vary depending on load & trim. That is what I go for.

 

[Jack Shellac]

Re: rpm questions in and out of water.

The back pressure when the motor is submerged will cause a different idle than when on muffs, but yours seems a little excessive. My OMC V-4 is 800 in the water and 1200 on muffs. Most of the data I've seen shows these motors to be most fuel efficient at around 4000RPM's, but there are a lot of variables to make a definite statement.