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.
Jon Kaase Racing Engines