replacement pistons end gap

[rebelrouser]

I am assembling a mild 350 Chevy, with a set of sealed power stock replacement pistons. There are no assembly notes in the box, but when I look up the part number it shows that they are hypereutectic type pistons. I have always used .065 per inch of cylinder bore for end gap for these type pistons, as opposed to .004 for cast style pistons. My question is that I see more and more engines that were built with cast pistons having hypereutectic style pistons as the OEM replacement when you order parts. I like hypereutectic style pistons no issues with that, just asking if you guys still use the wider end gaps for these style pistons, and the reduction in total ignition advance, when nothing comes in the box to tell you what to do?

[engineguyBill]

If the pistons do not specify ring end gap, then you can use typical gap dimensions. For a mild 350 engine .0045" per inch of cylinder bore for top ring and .0055" per inch for the second ring will be sufficient.
Icon recommends larger gaps for their Keith Black pistons, mainly due to the location of the top ring in relation to the piston crown. Remember, one of the primary functions of the piston rings, especially the top ring is to transfer combustion/piston crown heat to the cylinder walls and ultimately to the cooling system.