Dan, check the Silvolite webstie (assuming they have one!). The piston number looks like a Silvolite number anyway. Could be an old number though. Check with machine shops and/or auto parts stores, especially if you have a good raport with a counter person. They might be able to look it up for you. Are you sure this is a 401 bore block? Slightly over 4" (4.08, I believe), whereas the 360 bore is just under 4" (don't recall bore). On January 2, 2005 Dan Curtis wrote: > After doing quite a bit of research to see if I could find a picture of > pistons that looked like the ones in the freshly rebuilt balanced and > blueprinted engine that I bought a couple of years ago with the number 2381P > stamped on them, I discovered that the pistons look identical to 28cc valve > relief pistons for a 360 rather than the deep dish 401 pistons with an 8.5 > compression ratio as was suggested on this list so I suspect these are also > 28cc valve relief 401 pistons. The single most significant difference was > that the valve relief on the pistons in my motor are completely within the > dish area rather than more toward the angled sides of dish that the 8.5 > compression pistons have. Additionally, the pistons in my motor have a much > shallower dish depth than the low compression 8.5 compression 401 pistons > and in fact look like exactly like the 360 pistons rather than the 401 8.5 > compression pistons. ============================================================= Posted by wixList Archiver -- http://www.amxfiles.com/wixlist