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I have a 340 block. It has nice bores, but what size should they be? I also heard 360 rods crank and 080 over pistons in my 340 block make 372 ci? Can this be done with the crank spun down?
The stock bore size for a 340 is 4.040" and if you bore it +.040" (4.080") over and use the 360 stroke of 3.58" you get a cubic inch of 374. My main concern is that the 360 cranks have larger main bearing sizes then the 340 (2.81" vs. 2.50") which means you would be grinding away the heat treated surface of the bearing journal to get to the 340 size, if you had the crank heat treated after you ground it down this should not be a problem. Rather then going through the expense and hassle of grinding and heat treating the 360 crank you might want to consider getting a 4.00" stroker kit for the 340, it would probably be cheaper in the long run and with a .030" overbore and a 4.00" stroke you get 416 cubic inches.
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