Engine - Cylinder Heads - 18 degree Cylinder Head

From GM Performance - This cylinder head for competition small-block V8's represents significant performance improvement over the phase 6 head. The design moves the valve angle to 18 degree from its previous 23 degree. The valve centerlines are relocated .275 inch toward the intake manifold which positions the intake and exhaust valves on the centerline of the cylinder bore.

From GM Performance - These aluminum 18 degree cylinder heads were released for Chevrolet 350, 9.1 compression NASCAR racing engines. These heads are similar to P/N 10134364, except they have an additional .080 inch on the deck and an added .055 inch to the intake manifold flange to maintain port alignment. To raise the compression to meet your need, you can machine the deck surface.

From GM Performance - Designed for 9:1 compression racing engines. Same as P/N 10134364 except it has extra .080 inch material added to deck to increase combustion chamber volume. It also has .055 inch material added to intake manifold flange to maintain port alignment. Technical Note: This part uses casting P/N 10134363 and has semi-finished casting without seats and guides.

From GM Performance - This 18 degree V8 head is the same as P/N 24502580 except it is X-ray inspected to insure quality, then hot isostactic pressed (hipped) to remove porosity, and it then receives special low volume heat treatment. This head was designed for 9.1 NASCAR engines.

From GM Performance - Fully ported CNC head for 9:1 applications similar to P/N 24502569, except with intake runners configured for 9:1 compression and 390 cfm carburetor. This hed has beryllium copper intake valve seats and exhaust valve seats, and bronze valve guides. Fully CNC ported. Technical Note: This part uses casting P/N 10134363.