Fitment：For Predator 420cc Engine Hemi For Honda GX390 Engines Package include：1*Piston 1*Pin 2*Clamp Spring 5*Piston Rings 1*Connecting Rod 2*Bearings. 4.450" center to center for a 1.416" crank pin and a . 788" wrist bore. Note that the minimum clearance between piston and head is 0.030".Piston measures 660 from top of piston to top of wrist pin. Strength improvement: Use more durable materials to improve bolt strength and avoid bolt breakage. Bolts can reach 170 inches/lb. Uses 5/16" rod bolts. Use an inch pound torque wrench with a 1/4″ 12 point socket. 407cc using Stock Crank ,433 with +.160 Stroker Cranks , 440cc with .200 Crank.