Re: Differences between ’50’s era 30, 35 and 40 hp big twins?

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February 4, 2016 at 12:11 am #31311
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    quote Pappy:

    quote Chris_P:

    You CAN bolt a 40hp powerhead, onto a 35hp Super Quiet from ’58/’59 and have a sleeper. As stated, you cannot bolt a 40hp powerhead onto a 25/30/35hp single wall exhaust motor though.

    Wanna’ bet?
    I bolted up a ’74 40hp single wall exhaust to a 1957 35hp. single wall exhaust engine. Have to cut an eyebrow at the forward end of the lower bearing housing on the crank and match it on the mid section and use the later model gearcase……… Been there done that!
    Getting the clamshells to fit was the fun part (Ignition is different) plus a couple other smaller issues. If you cut the late model ventilation plate to match the 1957 profile and paint it nobody is the wiser!

    GREAT post!

    Typically I listen to all the experts then try it anyway 😆

    I mounted a Mercury gear case (for alternate gear ratios) to a couple of hot rod OMC’s so most issues can be tackled.