I bought a 360 engine with high compression pistons with L2426 on them. Anyone know what compression ratio they might be? Thanks

I would measure how far below the deck they are and then cc them and your heads...thats really the only way to know

These are TRW (now Speed Pro) high compression pistons with a pretty good dome on them. I tried to Google the number but found nothing. I was hoping someone on here might have a book with the number in it. They have to be 12.5 or 13-1 pistons. Just trying to find out what the advertised rating is.

My original 360 build was with a highly massaged set of those. Trimmed the dome and milled the underside of the dome to the tune of 30 or so grams. Overall, between pistons and rods I took 800 grams out of the rotating assembly. After I blew that up, my new KB forged 12.5's with Eagle h-beam rods were an additional 37 grams lighter per hole. I'm pretty sure that old TRW piston can't be used without a lot of checking and massaging of the dome.

This was a running dirt track engine. It was built by a chevy engine builder that left a wrist pin lock out, the pin rubbed the wall putting a nice gouge in it. One dead cylinder pumping lots of smoke.