OMC Gear Ratio Help??

[moomba]

I have a Evinrude E40ECUD serial number C1417092 that I am trying to find out what the gear ratio it is. I have a 60HP on this mid and lower and trying to do some research on proping the boat without buying to many props..

Thanks Steve

[Fast Fred]

two cyl? about what year? Nitro case?:cool:

[Mark75H]

You can always turn and count and not have to guess

[moomba]

two cyl? about what year? Nitro case?:cool:

Here is a photo of the motor. I think its mid to late 80's. It is a 40HP Mid and lower with a 60 HP powerhead twin. Also is a photo of the boat. It is now ready to prime and paint. It is around 200 lbs going to be center steer 4" jack plate and power trim. I am also going to put a low water pu and nose cone so it can be run high.

http://i289.photobucket.com/albums/ll213/1moomba/150HP%20and%20Misc%20used%20parts/046.jpg
http://i289.photobucket.com/albums/ll213/1moomba/150HP%20and%20Misc%20used%20parts/sept20200920328.jpg

[Mark75H]

That looks like real fun

Since it is mixed parts, I would absolutely suggest turning and counting to determine the ratio

[moomba]

That looks like real fun

Since it is mixed parts, I would absolutely suggest turning and counting to determine the ratio

Thanks will do tonight.

[thornl01]

stock ratio is 2.42, or 12/29.


serial # says 1987

I N T R O D U C E S

1 2 3 4 5 6 7 8 9 0

[moomba]

stock ratio is 2.42, or 12/29.


serial # says 1987

I N T R O D U C E S

1 2 3 4 5 6 7 8 9 0

Checked it out 2.42 I guess I should have done this from the start.

Any Idea what prop I will be able to turn on this boat?? and how many RPM's these 60 HP twins will turn??

[thornl01]

Biggest issue w/ these motors has been to NOT 'LUG',

ie... DO NOT OVER PROP !

Let the motor breath.

[JohnsonM50]

Biggest issue w/ these motors has been to NOT 'LUG',

ie... DO NOT OVER PROP !

Let the motor breath.
Ive heard that too, best not to hammer it at low Rs. Over proping also can dump performance.. losing both pickup & top end.