You guys got to be kidding! Lots of guys built these things and ran them for years--me, for example.
What's a Dirty Thirty and how do you build one? Take a 44 cube power head, put a Mark 30 crank in it (it fits and works fine), then mount it on a Mark 30 tower. The tiny impeller is up to the task--mine never overheated--but finding a prop with enough pitch is a problem. (The LU has a steep gear ratio--1.86:1 as I recall.) My buddy Dingy Bob scored a 17 pitch brass racing prop and fitted a 6 spline hub to her. That was the ticket for my 9 foot dink boat, and it ran great for years. I eventually went to a conventional Mark 55/ Merc 400 tower and LU simply because used props were easier to find.
Jeff
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