Pete Epple Technical Editor
August 17, 2012

New cylinder head designs are not something you see everyday. Even when something new does come out, it's normally adapted from something else, be it a race head or a more exotic engine. The trickle down from race-inspired engine parts has revolutionized the Mustang aftermarket, but as far as cylinder-head designs, few have strayed from the basic in-line valve configuration.

Jon Kaase Racing Engines has released its P-38 aluminum cylinder head ($2,550) for the small-block Ford segment of the Mustang and Ford aftermarket. What makes this cylinder head unique is its departure from the in-line valve design to a true canted-valve configuration. As each valve opens in a canted-valve configuration, it not only moves off the seat and straight down the cylinder, but towards the center of the cylinder bore. This unshrouding of the valves allows for increased flow and improved filling and evacuation of the cylinders.

"The canted valves open away from the cylinder wall," explains Jon Kaase, owner of Jon Kaase Racing Engines. "This allows for a freer flow of intake and exhaust gasses around the edge of the valves, as the valves are less shrouded by the cylinder walls. The benefits are mostly seen at high-lift (0.700-0.750-inch), but there is an improvement at low-lift as well. Because of the valve location (distance from the cylinder wall at low- and high-lift), the P-38 heads work very well on both a standard-bore 302 and a larger-bore engine, like a 427."

Inside the head, you'll find large-diameter intake and exhaust valves (2.10-/1.60-inch), a deep intake valve bowl, and sweeping short turns in the ports, which help improve port velocity. A large amount of the cross- sectional area in the ports is comparable to the Roush Yates NASCAR cylinder heads, which routinely crank out 850 hp. The P-38s are also equipped with bolt holes for large and small headers. These heads will work on any small-block Ford engine, without modifications and very few specialized parts. The heads were designed with the intake and exhaust ports in the stock location, so any SBF intake manifold and header will bolt up.

Due to the location of the rocker arms in the canted configuration, Kaase had to change the mounting location of the valve cover bolt holes, so only Kaase P-38 valve covers (included with the cylinder heads) will fit. Under the valve covers lies the only other part specific to the P-38 heads--the rocker arms. Due to the shaft width of most rocker arms, Crane rockers are the only arms found to fit with no clearance issues. You can use rocker arms from other manufacturers, but due to the shaft width, grinding will be necessary.

If you're looking for a unique set of aluminum cylinder heads, capable of supporting big power, check out the P-38 heads from Jon Kaase Racing Engines.

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Cylinder Head Specifications

Chamber Volume (CNC Machined) 60 cc
Intake Runner Volume 240 cc
Exhaust Runner Volume 86 cc
Intake Valve Diameter 2.100 inches
Exhaust Valve Diameter 1.600 inches
Intake Valve Length 5.450 inches
Exhaust Valve Length 5.450 inches
Intake Valve Angle 8 degrees
Intake Valve Cant 4.5 degrees
Exhaust Valve Angle 10 degrees
Exhaust Valve Cant 4 degrees
Valve Spring Diameter 1.550 inches
Valve Guide 11/32 inches

P-38 Flow Numbers

SuperFlow SF-1020 Pro Bench – 28-inches
Lift (Inches)Intake (CFM)Exhaust (CFM)
0.750 311215

Lift (Inches)Intake (CFM)Exhaust (CFM)
0.400285 194
0.500328 222
0.700350 238
0.750 355 241

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