1963 evinrude 18hp

valvebounce

Petty Officer 2nd Class
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Mar 18, 2014
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I bought this engine used,I have brought it back to good running order.
On a test run my 14ft fibregass boat would not get on the plane,the boat has remotes and steering and two seats,and isn't a heavy boat.
I think the prop is the wrong pitch.I can't find any Id numbers on the prop.
I suspect the prop that is on at present was for a heavier boat.
Anybody know what the standard prop part numbers are?
The prop is at the right height on the transom,and the wake is huge,but the boat won't plane.
I intend using the boat for close inshore fishing,but with the hull not getting on the plane I am only getting 8mph at best.Probably because the hull is in dispacement mode.
Any help will be much appreciated.
 

Sea Rider

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Sep 20, 2008
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12,345
Welcome to Iboats,

Before venturing going for a new prop, need to know if current one has alredy a spun hub, need to perform a hub slip water test to check that out. Does combo counts with a installed tach ?

Happy Boating
 

valvebounce

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Mar 18, 2014
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The combo doesn't have a tachometer,you have lost me,what is a spun hub?How is a hub slip water test performed.I'm pretty new to boats,and 71yrs.
I'm from Manchester in the uk,I have to trailer the boat to the nearest water 35-40 miles away.
 

82rude

Rear Admiral
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May 8, 2012
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Inside your prop there is a rubber hub which is pressed in there under fair pressure.Mark the rubber hub with a permant marker then mark the metal hub in the exact same spot.If after using the marks don't line up anymore you have a spun hub which means you need a new hub or new prop.Do you have a prop shop close by they can tell you if its shot easily.This may help http://marineenginedigest.com/diy/spunprophub.htm
 

Sea Rider

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If spun will need a new same one or one with less pitch to pull wot revs up.

Are there in UK many Evi prop pitches to play with. Which diam/pitch is current one ? WOT rpm can only be checked with a induction tach, if wanting to get the max out of that 18 will need to get one, are cheap for the work they do.

Happy Boating
 
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82rude

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P.S you have a motor that was produced from 57 to 1973 in the hundreds of thousands if not more .parts are abundant and reasonable and that motor was tuff,reliable and easy to work on.YOU have 4 prop sizes to chose from 7p 9p 10 and 11 p.7p is for heavy loads and 11 is for light loads most likely you have either a 9 or 10 p.Can you post a picture of your boat and motor?expecially from the side showing the motor and transom .I also wonder if maybe you have a shortshart motor on a longshaft boat?Ask lots of questions that's what were here for.
 

valvebounce

Petty Officer 2nd Class
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Mar 18, 2014
Messages
102
Inside your prop there is a rubber hub which is pressed in there under fair pressure.Mark the rubber hub with a permant marker then mark the metal hub in the exact same spot.If after using the marks don't line up anymore you have a spun hub which means you need a new hub or new prop.Do you have a prop shop close by they can tell you if its shot easily.This may help http://marineenginedigest.com/diy/spunprophub.htm

Hi,thanks for your interest,
there is no rubber hub in the prop,the prop is pin drive,the drive slot is like new,and the pin is straight and there is no play in the drive shaft pin drilling.
The gears are positive and there is no thump when they are engaged.
So I am assuming there is no prop slip.What do you think?
 

valvebounce

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Mar 18, 2014
Messages
102
If spun will need a new same one or one with less pitch to pull wot revs up.

Are there in UK many Evi prop pitches to play with. Which diam/pitch is current one ? WOT rpm can only be checked with a induction tach, if wanting to get the max out of that 18 will need to get one, are cheap for the work they do.

Happy Boating

The present prop is a 9.25" X 11" pitch.The WOT for this engine is 4500rpm.
I have laser tacho on order.
The prop I am thinking of getting is a 9" X9"pitch (012109)
 

valvebounce

Petty Officer 2nd Class
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Mar 18, 2014
Messages
102
P.S you have a motor that was produced from 57 to 1973 in the hundreds of thousands if not more .parts are abundant and reasonable and that motor was tuff,reliable and easy to work on.YOU have 4 prop sizes to chose from 7p 9p 10 and 11 p.7p is for heavy loads and 11 is for light loads most likely you have either a 9 or 10 p.Can you post a picture of your boat and motor?expecially from the side showing the motor and transom .I also wonder if maybe you have a shortshart motor on a longshaft boat?Ask lots of questions that's what were here for.

The cavity plate is 1" below the lowest part of the hull,it has a 15" to 16" leg.
I am having a little trouble posting a picture at the moment.
The present prop moves a lot of water,and lifts the bow somewhat,but fails to get out of the hole.It seems to be on the edge of planing.
At full throttle the speed is the same as at half throttle.I tried a 5hp yamaha engine that I have for the spare engine,the speed was more or less the same.
I think the 9" X 10" prop could be borderline,so I am considering the 9" X 9" prop (which has more cupping)
 

flyingscott

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Hi,thanks for your interest,
there is no rubber hub in the prop,the prop is pin drive,the drive slot is like new,and the pin is straight and there is no play in the drive shaft pin drilling.
The gears are positive and there is no thump when they are engaged.
So I am assuming there is no prop slip.What do you think?

There is absolutely a rubber hub in that prop. It sounds more like your motor is running on one cylinder. I would double check the health of the motor with a spark test and compression test.
 
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steelespike

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Apr 26, 2002
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19,069
I have to agree the prop has a rubber hub. The 18 on that boat could run close to 27 mph. When new, now somewhat slower.
We had a 18 on a big relatively heavy kit boat.It ran close to that speed.
 

82rude

Rear Admiral
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May 8, 2012
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Yes theres a rubber hub in there you just cant see it.I had a 14 foot wood boat with a 76 15 hp on it and it didn't want to plane,but my 57 18hp Johnson would easily pop up on plane.Spun hub or maybe like said earlier failing cylinder .You might also try to adjust the high speed jet when your close to planning ,I had to do that and the motor took off like a banshee.Sometimes just a 1/4 turn can make a huge diff.
 

valvebounce

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Mar 18, 2014
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102
Many thanks for your input gentlemen.
The prop is a pin drive,with no splines,I've got a 9 x9 on order.
There is no misfire on the engine,under load or otherwise.
I have fitted new coils and plugs and an impeller,replaced the gear oil,(the old oil was pretty clean)
At either full throttle or half throttle the boat does the same speed,the wake reduces at half throttle and the bow drops.I think the 9.25 X 11 prop that is on it
is the culprit,hence getting a 9 X 9.
My idea is to get on the plane and maintain the planing at a low speed.
 

flyingscott

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That motor will run incredibly smooth on one cylinder. Have you done a spark check? That is a free test. Have you replaced the points and condensers. Pin drive props have hubs in them
 
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valvebounce

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Mar 18, 2014
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There is a healthy spark on both plugs,the condensors are ok,The points were as new,I polished them up and reset them.
When I have tested the 9x9 prop I will let you know the results.
 

valvebounce

Petty Officer 2nd Class
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Mar 18, 2014
Messages
102
I have come to the conclusion that the 9.25 x 11 prop is slowing the engine down,similar to needing to change down a gear on a hill in a car.
The wake,although huge,has no trough in it,so the boat isn't moving along enough fast enough to enable the prop to reach the water in front of it,hence,no trough.
With the 9x9 prop the prop to water torque should decrease,and enable the engine to reach higher revs and get on the plane.
 
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