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1967 6 hp evinrude fisherman prop size

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Ruslmo

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I have a 3 blade 8 ¼ diameter by 8 inch pitch prop on a 1967 evinrude fisherman 6 hp. Factory is a 2 blade 8 inch diameter by 7 ¼ pitch. Is that a big enough difference to bog the engine when its turning the prop in water?
 
Define bog. Yes, it probably will reduce the wide-open-throttle RPM a bit, but I wouldn't expect a huge difference. If you are experiencing a big loss of power, you might consider looking for another cause.
 
Well it definitely doesn't seem to ever get to wide open throttle in the water. Without being in gear it gets there fine. I just replaced the rings in it this week. But seems to still lack power if you will, when it turns the prop in water. I rebuilt the lower end a few years back. Carb is clean I took it apart new kit etc.
 
That's a 9.5 prop - too much. My 12' empty jon boat will plane with the 6hp motor and stock prop. It will not plane with the 9.5 prop.
 
Okay latetest update. It turns prop in gear not in water fast fine and normal reaches peak rpm. Put it in water turn the prop it bogs to 3000 at the best but fluctuates 3000 to 2500 pretty up and down. Doesn't stay steady, checked spark and when jts running under a load with throttle wide open the tester looks like a light bulb no misses on fire. Carb has been gone through with new carb kit jet etc. What else could it be?
 
Okay latetest update. It turns prop in gear not in water fast fine and normal reaches peak rpm. Put it in water turn the prop it bogs to 3000 at the best but fluctuates 3000 to 2500 pretty up and down. Doesn't stay steady, checked spark and when jts running under a load with throttle wide open the tester looks like a light bulb no misses on fire. Carb has been gone through with new carb kit jet etc. What else could it be? I wonder if the fluctuating in the rpm is from the water sloshing in the barrel.
 
In gear and not in the water ?-----Hopefully you are suppling cooling water to the impeller.----Yes it will rev up fine with no load.---It will do that running on 1 cylinder.----Means nothing to me.
 
I noticed a small leak at the crankcase crack around an Inch from the top below the flywheel.
It seems to leak more when at full throttle. Its a decent little drip. Could this cause a power loss under a load?
 
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