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Old 03-22-2010, 08:27 AM
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Originally Posted by My79Ford400ciF1504x4
Hey, so if i bought a set of flat top pistons to replace my dished ones for my 400m, would there have to be any other changes made? I wouldn't have to change anything like rods I believe, but would i have to have the crank rebalanced to accommodate the new pistons?
First off- often the weight of an aftermarket piston will be similar to the OEM piston it replaces. Not always, and not exactly- but should be close. It's easy enough to weigh them both to see how they compare.

If the piston set is weight matched- or you do this op yourself- a rebalance isn't absolutely necessary, IMO. What will change is the balance factor (percentage of reciprocating weight to rotating weight), but only by a small amount. Since this factor is a compromise in the first place, if the OEM balance was good (which it often isn't), changing to a weight-matched set of pistons can be considered w/o rebalancing.

If you were swapping rods and pistons or swapping cranks, I'd have to advise you to rebalance it. But like Stroker_SS hinted at- if you can afford it- do it!
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