The principal power gains in Jon Kaase’s new P38 cylinder heads for Ford 302 (5 liter) and 351 small-block engines are derived from canted, larger diameter inlet and exhaust valves; improved port velocities; and deeper bowls with sweeping short turns in the intake and exhaust tracts.
To accommodate the original equipment intake manifolds and exhaust headers, Kaase’s P38 aluminum cylinder heads retain the outer appearance of the original Windsor heads. But the inner surfaces reveal modern-style combustion chambers and much more. To increase air flow to the cylinders, Kaase’s P38 concept features reworked ports and canted valves, their angles altered to 8 x 4.5 degrees and 10 x 4 degrees inlet and exhaust respectively. By canting the valves in this way they open toward the center of the cylinder and the gases are less encumbered by the shrouding effect of the cylinder wall. The intake valves are increased in diameter to 2.100in and the exhaust to 1.600in. On pump fuel and barely 9:1compression ratio the 302 engine with Kaase P38 cylinder heads, a modest camshaft, and an Edelbrock Junior intake easily generates 500hp @ 7,500rpm. The P38 operates with slightly altered intake valve pockets on the piston crowns, narrow stud-style rockers, appropriate guide plates, and different valve covers. Optional mounting holes for larger diameter headers are provided as standard.