4.320" pistons?

Just got a free set of pistons, Speed-Pro hypereutectic H535CP "STD". Compression height and pin diameter equate to 460 Ford, but the bore size is only 4.320". What engine would have the ~1.752" CH and ~1.043" pin, but the tiny little bore? Guy I got 'em from claims he used them in his 500" Caddy, but the pistons were too far down in the hole.

Just wonderin'.

You measuring right?

dfree383 wrote:You measuring right?

..Like possibly measuring the very top of the piston?  Google came up with Summit which says stock 460 bore (4.360):

https://www.summitracing.com/parts/slp-h535cp

Yeah, above the top ring land. Is that not the best spot? Please go easy on the flaming if I did it wrong.......also, using a cheap digital caliper so it's not TOO accurate..........

Thanks!!
Pete

Wrong place to measure, measure the skirts

Aha!! 4.357" with my crappy digital caliper on the skirt. Sounds better for an "STD" piston.

Thanks for the lesson!!
Pete

Galaxie427 wrote:Aha!!  4.357" with my crappy digital caliper on the skirt.  Sounds better for an "STD" piston.

Thanks for the lesson!!
Pete

Pete,
As an FYI , the ring land area is undercut from .030-.040 ( manufacturer and bore size dependent) because that area has the highest temperature and therefore most expansion. The skirts are turned "slightly" smaller than the bore because they are flexible and run at much cooler temperatures than the top. this can be as small as .0015 or as big as .010 , again material and manufacturer dependent.

Thanks! Makes sense to me, now.