1958 (qd19)Johnson 10 hp propeller

[Greg O.]

I just purchased a 1958 10 hp Johnson (qd19) with a spun propeller hub. I have a dinged prop off my 57 qd18 10 hp Johnson I thought I would through on it just for testing. I did not realize the older motors turned a larger prop, and there is no clearance between the cavitation plate and the prop on the 58. The prop off the 57 is a 9x10. The largest prop I find for the 58 is a 8.25 x 8 1/2. I am thinking the prop shaft on the 58 must be turning faster then the 57. Is this a correct assumption?

I will be putting this motor on a 14 foot Starcraft aluminum boat and would like as much speed as possible. Michigan wheel makes an 8 1/2 pitch, but Solas has a much cheaper 8 inch pitch. Will there be any noticeable difference in top end speed between the two ?

 

[steelespike]

According to brochures from that era. The 55, 56 and 57 had a 9" x 8" With a 8 1/4 X 81/2 beginning in 58 Gear ratios remained the same 1.73 changing to 1.76 in 61 still 8 1/4 X 8 1/2" I'm surprised they apparently changed the gear case in 58.

 

[Greg O.]

Defiantly a different gear case between the two years, even in the parts diagrams, numbers are different. Thanks for the info.