would changing props prevent/allow me from getting on plane?

[kfa4303]

Hi all. I was changing a shear pin today when I noticed that the prop on my motor was smaller than props on the same hp motor of the same era. I looked up the stock prop number and compared it to the one on the part and they were slightly different. The motor is a '61 OMC 10hp with a 8" x 7" prop, but I seem to remember reading about folks with the same motor running 9" x 11", or so. If I got the larger prop would it help me to get my boat on plane, or should I stick with the smaller one that's on there even though it doesn't exactly match the part number listed in the manual? Thanks.

 

[steelespike]

Re: would changing props prevent/allow me from getting on plane?

The motor came with am 8 1/4 X 8 1/2 That presently on iboats is the biggest prop.
If a 9 X 11 existed it would be intended for a very light application.
Higher number pitch offers more speed but less power. Lower number pitch more power but less speed This all depends on the application.The lower number would likely offer more speed on a heavy boat that has too high a number on it.
What size you need depends on your boat size and type.A tach and gps or speedo is necessary to tell if an application is working right.
The idea is to prop toward the max rpm with a light load.The 61 10 hp has a wot rpm range of 4500 to 5,000.