Small Block Chevy 400 Speed Pro Pistons This auction is for a new set (8) of Speed Pro hypereutectic Chevy 400 pistons - H616CP. +40 bore. Flat top piston with 4 valve reliefs. Anti-friction coated skirts. For use with 5.7" connecting rods. Includes pins and wire locks. Can be used with either pressed fit or bushed rods.