1962 evinrude fastwin on a 1236 aluminum john boat motor height.

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Chrisham

Petty Officer 3rd Class
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Mar 20, 2015
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87
The cavitation plate sets 2 inches below the boat bottom
It seems to take to long to plane out .It has a 2 blade brass prop.Does the motor need raising
 
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racerone

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Dec 28, 2013
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The 18 HP motor should make a 12' boat fly at 25 MPH.-----Are you sure motor is in good condition ? ----Properly adjusted carburetor ?----Running on both cylinders?
 
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Chrisham

Petty Officer 3rd Class
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Mar 20, 2015
Messages
87
2 inches?
racerone said:
The 18 HP motor should make a 12' boat fly at 25 MPH.-----Are you sure motor is in good condition ? ----Properly adjusted carburetor ?----Running on both cylinders?
Click to expand...
Yes sir runs fantastic .cranks first pull and idles fantastic.Just got her running with your help.It will get fast but takes a while to get there.I was wondering if the low cav plate is plowing making it hard to get planed out
 
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airshot

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Jul 22, 2008
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Raise motor until cav plate is same height as boat hull....is cav plate level to boat hull, use long straight edge to check. How is motor trimmed ?
What is compression on both cylinders ? Why a two blade prop ? You need a tach to get real readings in motor performance.
 
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Chrisham

Petty Officer 3rd Class
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Mar 20, 2015
Messages
87
airshot said:
Raise motor until cav plate is same height as boat hull....is cav plate level to boat hull, use long straight edge to check. How is motor trimmed ?
What is compression on both cylinders ? Why a two blade prop ? You need a tach to get real readings in motor performance.
Click to expand...
The cav plate is 2 1/4 inches below the hull.Compression 112 both cylinders cold.Motor was trimmed all the way down
 
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racerone

Supreme Mariner
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Dec 28, 2013
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If your " cool looking " prop has too much pitch , then acceleration will be slow.-----Have you adjusted carburetor mixture screws for proper performance , yes , no or no idea how?
 
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Chrisham

Petty Officer 3rd Class
Joined
Mar 20, 2015
Messages
87
racerone said:
If your " cool looking " prop has too much pitch , then acceleration will be slow.-----Have you adjusted carburetor mixture screws for proper performance , yes , no or no idea how?
Click to expand...
I set them at the factory settings .No I have not reset them.seems like motor is doing good great starting and idling for sure
 
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Chrisham

Petty Officer 3rd Class
Joined
Mar 20, 2015
Messages
87
airshot said:
Is the motor a long shaft mounted on a short 15" transom ? Pics may help us figure your issues...
Click to expand...
The boat transom is 16 inches.on the motor bottom of the mounting bracket to the top of the cavitation plate is 18.I also measured a 72 25hp johnson a 15 hp johnson and a9.5 hp johnson all appear to be 18 inches.I also measured a 30 hp johnson and it's 22.So I assume it is a short shaft
 
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