I/O (Sterndrive) Conversion to Outboards

[flashback]

Way I see it, your bolt threads will be coated with putty, may as well just run the nuts up and call it good. I've mostly experienced galling when removing the nuts not so much on installation.
I also think you may want to put a spacer type border, a tad less thick than the spacers, around the big access holes so the putty doesn't get squeegeed out too much.

 

[tpenfield]

If it's not grinding, it's drilling . . .

I went through several cobalt bits . . . amazing what a sharp drill can do . . .

It reminds be of way back, when I was a young engineer in an electronics manufacturing company. The VP said "the printed circuit board fabrication line was having problems . . . go check it out" . . . A couple of weeks later things were running smoother. He asked what the solution was . . . I said "drill bit sharpening. . . . "

Anyway, I digress. After several days . . . here are the bolt holes.
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34 bolts on the transom faces and 10 bolts overhead . . . 44 total. I may add a few more once the extension bracket is installed. When I had 80 bolts in the plans, the naval architect told me I could go with about half that number. So it is . . .

I have installed/removed the extension bracket a several times over the past few days. Each time I check the alignment to make sure the thing is not 'walking around' on me. Looks good and repeatable.
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That will be important when I install the E-B for real, but I will check it then anyway.