Enthusiasts wanting to build a high performance 265-307 small block Chevy traditionally had two choices for a bolt-on cylinder head – a set of refurbished factory cast iron heads or aftermarket heads made for large-bore (350ci and above) engines.

The first option was expensive and didn’t make all that much more power, while the second left horsepower on the workbench because the valves in the large-bore heads were shrouded by the smaller cylinder bores.

Now Summit Racing has a better choice made just for small-bore Chevy owners. Edelbrock’s Performer RPM Small-Bore Cylinder Heads are engineered for use with small blocks that have 3.736 to 4.000in bores.

The secret is in the valve spacing, which is reduced to 1.817in to accommodate the smaller cylinder bores. The Performer RPM Small-Bore heads feature compact combustion chambers and highly efficient ports for improved performance and great throttle response throughout the RPM range.

The Performer RPM Small-Bore Cylinder Heads are available fully-assembled with stainless steel valves; valve springs; locks and retainers; 3/8in rocker arm studs; and hardened guide-plates for use with 5/16in pushrods. Your choice of cylinder heads for use with hydraulic flat tappet or hydraulic roller camshafts. The head is also available as a bare casting.