This listing is for a set of (8) +.030 over size Flat head w/2-valve relief Coated skirt piston from Silvolite Pistons. Silvolite has been making pistons since 1922. This set is +.030" Over Bore and are Compatible replacements for early model 1972-1990 Ford 460 V-8 - 4.390" bore diameter. These can be used in Mercruiser boat engines equipped with the Ford 460 engine. These are Not OE duplicate pistons. These replace the Oblong Oval recessed OE pistons. Use these as a performance upgrade. Use in sets only. Compression distance: 1.752". Ring grooves 5/64" 5/64" 3/16". Pins included 1.040" pin diameter-Press-fit only. For stock 6.605" length rods. Stock 3.850" stroke.