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Author Topic:   JE pistons
Dirt Maniac

Total posts: 113
posted November 26, 2001 05:52 PM
Where can I find info out about what stroke and connecting rod a set of pistons was made.
I acquired a set of flat top JE pistons from a sprint car team, but don't know their combination. I checked and JE's website is currently down for maintence. Measuring the piston with a dial calipers, what should the piston measure for a 4.155" bore???

Dirt Full Roller

Total posts: 58
posted November 26, 2001 10:18 PM
Small block 400 .030 over is 4.155.

Dirt Maniac

Total posts: 113
posted November 26, 2001 11:42 PM
I know the bore size, what I'm looking for is the diameter measurement of a piston for a 4.155" bore. What amount is the piston diameter undersized in relation to the 4.155" bore??? I have some bare pistons and I'm trying to figure out what bore they are made for. I know they're made for a +400 cubic inch motor. Sounds easy, but not sure if they are 10, 15, 20, or 30 over pistons. Need some technical measurement guidance. I know someone has to have a JE Piston catalogue with these measurements. I also would like to know the compression and pin height for 5.7, 5.85, and 6 rod lengths, so I can figure that out too. All help is appreciated.

Dirt Freak

Total posts: 247
posted November 27, 2001 11:26 AM
As for the piston diameter, JE does not list it in their catalog, they only put it on the box the pistons came in. For a 4.155" bore the piston would problably measure between 4.149" - 4.152". You need to take this measurement 1.300" below the oil ring.

As for what rod the pistons use it would depend on what crank stroke they where designed for. ( Compression Height is measured from top of piston to center of wrist pin ) So you will have to measure compression height or pin height of the piston. You do this by measuring from the top of the piston to the bottom of the wrist pin, then measure the diameter of the pin, divide the pin diameter by 2, subtract that measurement from the pin height measurement, this will be your compression height. From that I can tell you what rod and crank stroke combinations will work with the pistons you have.

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