Fd-10 bored out to 18hp

[jacksboat]

I have been restoring my grandfather’s 1956 johnson fd-10 15hp. Just wondering if anyone has tried boring it out to get the 18hp that the next year’s model has.

[frankr]

Don’t do that. Get a ’57 powerhead. It’s better.

[1946zephyr]

Exactly. Both have the same exhaust housing and everything bolts up. No need for boring.

[chinewalker]

Agreed. To get the bore right, you’d be removing a LOT of material from the sleeve, possibly leaving it too thin to hold up. And then, your cylinder head wouldn’t fit, as the larger pistons would hit it. So then you’d need an 18hp cylinder head. Much easier to find an 18hp powerhead and run with it…

[garry-in-michigan]

If you (or if you know someone who) could weld the motor cover brackets on the cylinder head, a 25 horse powerhead would be a lot of fun. . . 😆

[1946zephyr]

quote Garry in Tampa:

If you (or if you know someone who) could weld the motor cover brackets on the cylinder head, a 25 horse powerhead would be a lot of fun. . . 😆

That’s right. I forgot about the 1969 -73 25’s. Good idea Garry 😎

[jacksboat]

Thanks all. I’m def gonna leave jack’s motor stock. I’d love a bigger one but have to be true to the old boat.

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