Posted by Matt Wilson [108.162.221.211] on Tuesday, June 27, 2017 at 15:13:43 :
I bought a set of new Sealed Power pistons for my long block flathead, and I discovered that the pins just slide right out of them if I tip them sideways just a little. This seems contrary to what my rebuild manuals say, which is that the fit should be such that it requires firm thumb pressure to move the pins in the bores of the pistons at 70 deg F (room temperature).
I contacted Sealed Power and they responded by saying that the clearance between the piston and the pin is 0.0004 to 0.0007" and they added that with honing oil as the only lube, the pins should slowly slide out if their bores under gravity. As I said, mine slide out without any lube, but with any amount of clearance, I believe this would be the case. So I doubt the parts are mis-manufactured, but they are certainly different in this regard than what's described in the manuals.
I imagine the fit of the pins in my pistons is probably just fine, but I was wondering if you guys had noticed the kind of thing I'm talking about with new Sealed Power pistons, or any new pistons, for that matter.
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