This is a used matched set of NASCAR Chevy R07 aluminum cylinder heads from Hendrick Motorsports with used titanium valves. They are open race heads not restrictor plate heads. These have been CNC ported and have beryllium copper intake and exhaust seats, bronze valve guides and have titanium 2.200 6mm intake valves and 1.610 7mm exhaust valves. These are just like they were removed from the engine at Hendricks and cleaned. The combustion chambers are approx. 45cc's, rocker arm stand studs are included. These heads will make 850-900 HP on a 358 CID engine with 850cfm carburetor. 16- T&D rocker arms 2.10 and 2.20 ratio are on another auction. All looks good ready to be used again. The NASCAR teams have about $10000 in a set of these heads, so take advantage of this Ebay blowout price now!