Jon Kaase: Lifting The Shroud

(Article begins on the Tech, Tests & Installs page HERE)

Being 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 wall.

The 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.

For 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 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 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.

Text by Ro McGonegal; photos by Moore Good Ink

Jon Kaase Racing Engines

The head of the 2.100-inch intake valve maintains stems measuring 11/32 x 5.450 inches; the stems of the 1.600-inch exhausts are 11/32 x 5.460 inches
With a mechanical roller camshaft, the valve springs have an installed height of 1.950-inches and generate seat pressures of 240lb. Open pressure is 500 to 600lb. As the action is quicker on a mechanical roller system, greater spring pressure is required to maintain contact between the roller tappet and the cam lobe. In contrast, seat pressure for a hydraulic roller system might be 145 to150lb.
Naturally, the P38 head employs stud-mounted rockers. Most rocker arms will readily adapt to the P38 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. Trend pushrods operate within these 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.
In addition to the P38 head kits, Kaase constructs fully built P38 engines, each complete with dynamometer sheet and video.
As a canted-valve construction, the arc of at least one of the rockers on the P38 interferes with the conventional rocker cover. Kaase’s exclusive cast aluminum covers eliminate the problem. As a clean-sheet design, it was also easy for him to increase clamping power: the rails on the P38 head are configured for eight (rather than the usual six) fasteners.
The P38 conversion accepts any Windsor intake manifold, including EFI types, but the Edelbrock Super Victor and Victor Jr. have proven the most effective so far.
When Kaase ships a complete engine, it will likely be accompanied by a Demon carburetor—it is flow-rate matched to displacement as well as purpose.
The P38 cylinder heads have mounting provision (2-inch centers) for conventional tubular exhaust headers as well as wider (3 inch) centers that allow for larger exhaust ports.
Most Kaase crate engines employ Diamond forged pistons engineered for the application. On the other hand, if conventional pistons are required, they need a small valve relief (no more than 0.125-inch at the outer edge) to accommodate the canted angle of the intake valve. This is a simple fly-cut operation aided by a hand drill.
Kaase: the Pro Stock engine master who achieved a remarkable 1.7ft-lb torque per cu in (103ft-lb/litre)