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Unread 03-31-2008, 09:50 PM
nymack66 nymack66 is offline
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Join Date: Jul 2007
Location: Orlando Florida
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Quote:
Originally Posted by THEFERMANATOR View Post
Your pictures and your model number comes out to a 20" shaft, and your certain you have a 15 spline shaft. So this means like LORD SKOOLS said, you got the wrong lower most likely. The 15 spline 20" leg lower is one RARE bird to find, so somebody probably swapped in a V6 leg. Problem being that the V4 don't have the power to spin a 1.86:1 ratio and make any power. Sounds like your gonna need another lower unit. The first thing I would do at this point is get a rough idea of your gear ratio. Take the cowling of the engine off and remove the spark splugs from the engine. Rotate the flywheel by hand until the #1 top dead center mark is lined up with the timing marker on the front of the engine and mark the 2 points. Now put the engine in forward and mark where the propeller is at. Now rotate the flywheel by hand counting the revolutions of the flywheel and propshaft until the prop makes 1 full revolution. If you rotate the flywheel just shy of 2 full turns to one rotation of the prop you have a V6 lower unit. If you get 2 and 1/4 turns of the flywheel to one revolution of the prop, you have the V4 lower.

If you have a V6 lower your engine will NEVER run right. LAND N SEA did a nice write up on prop curves vs engine power curves and how you have to match the 2. If your engine isn't at it's peak power point when the prop is at it's peak efficiency point, then it runs like crap. Simply changing your prop pitch won't give the desired effect as changing the gear ratio will. Make sure your of what your ratio is first, and then go from there.
You were right on, Its a V6 gearcase base on the instructions ,just like you said shy of full turns I have one complete rotation !!Thanks man , Like it sys many will be called ,few will be chosen , you are the chosen one !! The best of the bes looked at this and could not have figured this out ..Once again thanks , I will prep the spare v4 unit and bolt up ..Will keep you posted . Thanks guys keep up the good work ..
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