Re: 1954 Evinrude 7.5hp increase power?

[Don]

Well, not quite…The 5.5/7.5 uses a different style of propeller and drive pin location than the 1958 and newer 9.5/10hp models. The 50s model 5.5/7.5s use a solid prop (no rubber hub) with a drive pin near the outer end of the prop shaft, there is a rubber cap that snaps in place over the drive and cotter pins….The early 6hp models used this same style prop…
The 1958 and newer 9.5/10hps (along with later model 6hps) used a propeller with a rubber hub and a drive pin located right near the prop shaft seal, the prop shaft is threaded on the outer end to receive and plastic threaded cap and cotter pin.
So, I would say that propco’s grouping of a single propeller style from 1954-1981 is a mistake.
And yes, the 5.5/7.5 models used the same style prop shaft/prop setup with different pitch props. The early 6hp models used this same setup, the later models used the same setup as found on the 1958 and newer 9.5-10hp models, just different pitch props.
I will look on the propco website, perhaps I can get a better idea of what is needed for your engine…

OK, I looked at the Propco website. I don’t understand how one hub can be made to fit the two different style setups, you should contact Propco, perhaps it is some of universal hub that can be made to fit both styles….