Pelican Parts Forums - Piston pin offset

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Would not hurt at all, probably will not help much either. At this point, the biggest benefit is to you feeling more confident (which does count for a lot, not trying to be facetious) about that part of your engine assembly. But, did you mean half a thousands, or 5 thousands?

Half a thou. .0005".

Piston orientation

Quote:

Originally Posted by reclino (Post 11045067)

I was not proposing doing this for a hp benefit. If reducing slap reduces the shock load on the pistons by a small amount. Then why not reverse 3 pistons so all of them see the benefit. I have had the stock cylinders re-plated, the rings are total seal with Napier profile on the 2nd ring. The stock pistons at 68k miles had about .0005" of wear on the skirts. They are going to have to wear into their "new" cylinders anyway, what would it hurt putting 3 in backwards.

If the pistons have any dome, there should be valve pockets machined into the piston, a large one for the intake and a smaller one for the exhaust valve. They can only go in one way so you would need 3 with the pin offset for the left side and 3 with the pin offset for the right side. If the pistons have no dome or a dished top then you theoretically could turn them over. You will have to measure carefully to find the offset side!

Stock pistons, there is no dome, there are no valve relief cuts.

With .0005" wear on the pistons, why bother with cylinder replating? By memory that would leave another .003" before considered worn out. Did the bores distort dramatically or have very serious scuff marks in them?

The cylinders were not round enough. Common problem for the 930 cylinders.

Tell me about it, not the most stable design not having fins all the way around on a very thin casting. That is why I ended up going with JB Racing fully finned cylinders with steel liners.