Specifications include, but are not limited to: 1 set Custom Cylinder heads Matched set of custom cylinder heads specifically for late model stock car racing per the rules implied by NASCAR. The heads must meet all rules and tolerances to be deemed legal. The heads are FLOWED to match the specific motor and intake along with the carb used. Each head goes through a rigorous test to match each valve, lifter and rocker arm to match our motor that it will be assembled on. Each head must have the correct valve angle job. These are the specs before machining and matching: 227 CC intake 66 CC combustion chambers Angle Plugs 2.08 intakes 1.60 Exhaust Quote needed for completed heads, machine work, Flow bench time, fitment , assembly and dyno.