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#11
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I ain't got no idea what the correct compression should be but I'd tend to believe 90psi and above should be good. And hope for less than 10% difference between the cylinders.
Have you tried to reposition the engine up a hole or two? I'm guessing about 3/4" above the bottom of the boat (cavitation plate) should be close.
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 '75 Cuddy with '00 Johnson Ocean Pro 150 horse Benny 
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#12
07-28-2011, 06:37 PM
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Right now my cavitation plate is level, maybe a hair lower, than the keel. I will set up a scaffold frame tomorrow and lift her up. How many holes? Right now the top bolt is in the 2nd hole from the top.
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1983 V-20 capsized. . . . in the garage.
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#13
07-28-2011, 07:26 PM
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You can do it easier by using the skeg of the motor (with a board under it)
and the trailer tongue jack. With the engine tilted down, place the board under the skeg and then crank the tongue jack till the skeg contacts the board. Loosen the bottom engine mounting bolts then remove the upper bolts. Crank the tongue jack up till the desired hole is reached. Reseal and rebolt the engine. I'd level the cavitation plate with the bottom of the boat. Then measure to find out how much or many holes to be about 3/4" above the bottom of the boat with the cavitation plate. That should give you a good starting point. Keep in mind, on most boats the cavitation plate being level with the bottom of the boat is the normal starting point to see where the best location is. These V's have a pretty steep angle and may need to be a little higher than others. There are other factors that will contradict this method but it's a starting point.
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'75 Cuddy with '00 Johnson Ocean Pro 150 horse Benny Last edited by tsubaki; 07-28-2011 at 07:32 PM.
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#14
07-28-2011, 07:47 PM
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When running it the other day, i noticed the water was 2-3 inches above the cavitation plate. But that was with the doel-fins on. I took them off for another run and forgot to check how the water was coming out.
I like your idea tsubaki. That is probably how i will do it. FYI top end and rpms didn't change with the doel fins on or off. The only thing i noticed was in turns the boat was more stable with the doel fins.
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1983 V-20 capsized. . . . in the garage.
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#15
07-28-2011, 07:50 PM
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Every engine we ever came across that had those things on them we took them off.
I'd say 90% of the time most of the problems can be fixed without them by proper weight balance in the boat and correct engine height. Why don't they come on engines to begin with? Remember, loosen the bottom bolts. Don't remove them. Just enough to let the engine slide on the transom.
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'75 Cuddy with '00 Johnson Ocean Pro 150 horse Benny
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#16
07-28-2011, 10:08 PM
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I run with Doel Fins on. They came with the boat when I bought it, and since they were there I said what the hell and they've been there ever since. They do help (or so it seems to me at least) in higher speed turns... keeps my stern from wagging out as much. But again, it's a subjective thing and what I like others might find unacceptable.
__________________
1987 V20 w/1987 150HP Yamaha on a Shoreland'r Trailer 1978 16.5 Airslot w/1996 120HP Force on a Four Winns trailer 1996 V21 w/1993 200HP Mercury on a Shoreline Trailer All towed by a 5.7L Hemi Durango. If God didn't have a purpose for us we wouldn't be here, so Live simply, Love generously, Care deeply, Speak kindly. (Leave the rest to God)  Silence, in the face of evil, is itself evil. Not to speak is to speak, not to act is to act. God will not hold us guiltless.
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