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Old 12-30-2014, 06:11 AM   #205
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Join Date: Jul 2010
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Default Re: Boring a flathead

Originally Posted by 31pickemup View Post
I just pulled my flathead and it ended up being a 1941-42 that has a 3 3/16 bore but it's not a mercury. Is there still life in her? How much can you go on that year a motor and be safe?
If I recall correctly they will generaly go 0.060" over 3 3/16". I think Walt has taken some of these out to 3 5/16".
Just to clarify, were talking 21A here, no round water hole in the middle?
I'd have thought, if you bore just enough necessary for a good bore, you should be fine. Have you measured to see whats needed?
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