You need to get on a compression calculator. If you plan on using pump gas an increase in stroke greatly affects your compression ratio. So figure out what heads your going to use and the size of the combustion chamber and your bore and stroke. If using aluminum heads you will want to keep your compression below 11:1 preferable 10.5: to be on the safe side. You will need to figure how far the piston will be in the hole, the size of the valve reliefs etc. A forged crank is a good choice if it will be driven a lot and driven hard or raced. A 4.25 stroke will give you more torque and HP but you need to make sure your target compression ratio is in order.
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Tim Corcoran
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