The CL4 is specifically designed for the NKA rule package. With no minimum duration requirements, we were able to smooth the nose of the cam allowing it to rev well into the 7000 RPM range. The CL4 shows gains in the 6600 RPM range over our current CL3. This cam comes buffed, further smoothing the nose, to take max advantage of the 10.8 springs. The CL4 is not legal for AKRA. The lobes are hardened for extra durability, extending the life of this cam. Specs: Engine: 196cc OHV Clone, Predator 212cc Hemi Recommended Class: NKA Unrestricted Stock Classes Target (MAX) RPM: 6900-7100 Spring Pressure (In / Ex): 10.8 lbs Valve Lash (In/Ex): .001" Ignition Timining: 34-36 Deg BTDC Profile: Intake Exhaust Open 28.75 BTDC 66.30 BBDC Close 75.25 ABDC 40.52 ATDC Lift .224" .231" C/L 114.0 ATDC 103.5 BTDC DUR @50 220.1 Deg 223.5 Deg DUR @200 79.90 Deg 89.45 Deg