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How big can you bore an "80 inch shovel?

Post Wed Jan 18, 2017 1:02 pm

Posts: 1708
Location: Interlaken, NY USA

To be exact, a customer has a pair of 78 casting number cylinders that are at .020" over 3 7/16" bore. I presume that they are from a late 74 inch shovel that was put together with late casting cylinders at the earlier bore size. Anyway, he's already got a pair of .040" over EIGHTY pistons that he wants to use in these cylinders. A cursory cruise of the internet seems to say don't take 80" cylinders more than .030 over 3 1/2.
The internet being what it is, I thought I'd ask here where I can get an opinion I can trust!
By the by, this is supposed to be an 80 shovel when I'm finished, I've redone the rods and am waiting for the pistons to balance the bottom end.
Thanks in advance

Posts: 20
the 74 and 80 cylinders are different , 10 fins on 74 , 9 fins on 80 . theres height also . look at S&S info .
keen to see what happens here

Posts: 654
Location: Wisconsin, USA
No sense in boring those cylinder out that much. 80" cylinders are available and cheap. I had a couple of crates full of low bore cylinders left over from the S$S Sidewinder days and had a hard time getting a hundred a pair when I decided to lose the weight recently. Lots of 3.5 plus 040 bore machines out there staying together. I probably have a pair left if you haven't found a solution.


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