begins on the Tech, Tests & Installs page HERE)
a racer, he knew the value of stealth. But more importantly,
being an engine builder he knew the prime advantages of
canting the valves to open towards the center of the cylinders
and so mitigate the natural shrouding effect of the cylinder
P38 cylinder head was designed primarily for the 302W (8.2-inch
deck height, 4x3 bore/stroke, 5.095-inch rods); its derivative
the popular 347ci (over bored by 0.030-inch and stroke increased
to 3.400-inch); the 351W (9.5-inch deck height, 4x3.5 bore/stroke,
5.960-inch rods), and the 427-454W Sportsman-type Dart block
(9.5-inch deck height with 2.750-inch Cleveland main journals).
Combustion chamber volume is typically 60-62cc.
better cylinder filling, Kaase envisioned valves canted
at 8x4.5 degrees on the intake and 10x4 degrees for the
exhaust. The new territory produced by this modification
would allow him to increase the diameter of the valve heads
to 2.100 inches and 1.60 inches and by astute CNC porting
he would induce far superior air flow and cylinder filling
compared with any conventional layout. The revised angles
place the intake valve advantageously in the cylinder bore
and the CNC porting is much more efficient than the original.
It also has the qualities of a sweeping short-turn radius
(on the floor of the port) and deeper valve bowls, giving
the atomized fuel improved entry to the combustion chamber.
Assume a 2.100-inch intake valve yields 350cfm in a port
with a given cross-sectional area. Then assume that you
increase valve size to 2.200 and the engine yields 360cfm;
the result could actually indicate a loss in performance.
Such is the consequence of increasing the intake port and
losing the air velocity because the opening is larger. Sophisticated
petrol heads know it doesn’t pay to increase CFM unless
there is a simultaneous gain in air speed. Then, because
the P38s flow so well at 0.400-0.500 inches of valve lift,
the camshaft could be tailored with 5- to 10-degrees less
duration. This usually results in smoother idle and better
low-end manners. These Kaase heads favor camshafts with
close lobe centers that tend to produce more power.
Though the 351 Cleveland could be coerced, its coolant flows
through the front of the block and into the cylinder heads.
With the Windsor, coolant flows through the intake manifold.
Certainly, the Cleveland’s redundant passages could
be blocked off, but Kaase’s wisdom is to use the Windsor
block that is stronger, readily available and requires no
On pump fuel and with barely 9.0:1 compression ratio, a
modest mechanical roller camshaft, and an Edelbrock Victor
Jr. intake manifold, the Kaase 302 easily produces 500hp
at around 7,500rpm. At the other end of the power spectrum,
a Kaase-equipped 392ci OE cylinder block belts out 650hp
all day long but is fully capable of producing 700hp and
beyond if desired.
Including valve covers and valve cover gaskets, the P38
heads are supplied with larger valves, springs, seals, retainers,
rocker studs and guide plates installed. Complete P38 engines
are also prepared at Kaase’s facility. These are accompanied
with dynamometer test results and often a video. Dyno tests
ensure the engine is producing the expected power output
and is free of oil and water leaks.
by Ro McGonegal; photos by Moore Good Ink
Jon Kaase Racing Engines