Jon Kaase P38 Cylinder head Jon Kaase’s P38 Canted-valve Windsor Cylinder Heads Aim For Better Cylinder Filling Text by Ro McGonegal Photography by Moore Good Ink

Jon Kaase keeps his eyes peeled. Over the years, the engine builder has seen an endless string of improvements and aftermarket components visited upon the Windsor 302 but he was woefully aware that there were no real advancements beyond the original cylinder head configuration. He thought he could produce castings that looked like ordinary Windsor 302/351 parts on the outside but would be entirely different from the original blueprint on the inside.

As a racer, he knew the value of stealth. But more importantly as an engine builder he knew the prime advantages of canting the valves to lean towards the center of the cylinders and so mitigate the natural shrouding effect of the cylinder wall.Kaase designed the P38 cylinder head primarily for the 302W (8.2-inch deck height, 4×3 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, 4×3.5 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). Typical combustion chamber volume is 60-62cc.To insure optimum cylinder filling, Kaase canted the valves at 8×4.5 degrees on the intake and 10×4 degrees on the exhaust. The fresh area created by the new valve angles allowed an increase in the diameter of the valve heads to 2.100 inches and 1.60 inches.Astute CNC porting would induce far superior air flow and cylinder filling compared with any conventional layout and it accomplished two things: the revised angles place the intake valve advantageously in the cylinder bore and the CNC porting is much more efficient than the original as-cast configuration. 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 a more streamlined entry to the combustion chamber.For argument’s sake, let’s assume that 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 port yields 360cfm; the result could actually indicate a loss in performance–increasing the intake port and losing air velocity because the opening is larger. Bottom line? It doesn’t pay to increase flow unless there is a simultaneous gain in air speed.The P38s flowed so well at 0.400-0.500 inches of valve lift that the camshaft could be tailored with 5- to 10-degrees less duration, resulting in smoother idle and better low-end manners. As such, the Kaase heads favor camshafts with close lobe centers that tend to produce more power.With the Windsor engine family, coolant flows through the intake manifold. The 351 Cleveland could certainly be coerced, but its coolant flows through the front of the block and into the cylinder heads. Certainly, the redundant passages could be blocked off, but Kaase’s simple wisdom is to use the Windsor block that is stronger, readily available and requires no modification.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 sings a 650hp song all day long and is capable of producing more than 700hp.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 a Kaase mainstay and are accompanied by 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.
Windsor Intake manifold

Virtually any Windsor intake manifold, including EFI types, can complete the P-38 conversion, but the Edelbrock Super Victor and Victor Jr. Buy weed seeds from Bushweedo & we will guarantee the best marijuana seeds prices available anywhere. Seeds always shipped with discreet delivery!. have proven the most effective so far.

P38 engine kit includes carburetor

When Kaase ships a complete engine, it will likely be accompanied by a carburetor that has been flow-rate-matched to displacement as well as purpose.

P38 Cylinder head ports

The P-38 cylinder heads offer “adjustable” exhaust mounting provisions, 2-inch centers for conventional tubular headers, as well as 3-inch centers that allow for even larger exhaust ports.

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The P38’s Advantage: Extra Cylinder Filling from Canted Valves

The intake valve measures 2.100-inches and maintains an 11/32 x 5.450 inch stem; the stems of the 1.600-inch exhausts are 11/32 x 5.460 inches.

greater valve spring pressure is required

Because the action is quicker in a mechanical roller system, greater valve spring pressure is required to maintain contact between the roller tappet and the cam lobe. Springs have an installed height of 1.950-inches and generate seat pressures of 240lb. Open pressure is 500 to 600lb. In contrast, seat pressure for a hydraulic roller system might be 145 to150lb.

fulcrum shafts need touching-up with a grinder

Most stud-mounted rocker arms will readily adapt to the P-38 cylinder heads but because the valves are canted, the ends of some of the fulcrum shafts may need a touch-up with a hand-grinder. Push rods operate within guide plate slots, which prevent the rockers from rotating on their axis and ensure that the ends of the rocker arms remain centered on the tips of the valves.

P38 heads installed

In addition to the P38 head kits, Kaase concentrates on building complete engines and documents the results with dynamometer sheet and video.


Cylinder Head Covers

Since the arc of at least one of the canted-valve rockers touches the conventional rocker cover, Kaase’s own cast aluminum version eliminates the problem. The opportunity provided impetus to increase clamping power, so the rails on the P-38 head accept eight rather than the usual six fasteners.


If conventional pistons are used, they’ll require a small valve relief (no more than 0.125-inch at the outer edge) to accommodate the angle of the intake valve

Kaase builds most of his crate engines with forged pistons engineered for the application. If conventional pistons are used, they’ll require a small valve relief (no more than 0.125-inch at the outer edge) to accommodate the angle of the intake valve. This is a simple fly-cut operation accomplished by a hand drill.

Pro Stock engine master

Kaase: the Pro Stock engine master achieved 1.7lb-ft torque per cu in (103ft-lb/liter)

  Complete Engine, Jon Kaase P38