Written by Moore Good Ink
Winder, Georgia: The principal power gains in Jon Kaase’s new P38 cylinder heads for Ford 302 (5 liter) and 351 small-block engines are derived from canted, larger diameter inlet and exhaust valves; improved port velocities; and deeper bowls with sweeping short turns in the intake and exhaust tracts.
To accommodate the original equipment intake manifolds and exhaust headers, Kaase’s P38 aluminum cylinder heads retain the outer appearance of the original Windsor heads. But the inner surfaces reveal modern-style combustion chambers and much more.
To increase air flow to the cylinders, Kaase’s P38 concept features reworked ports and canted valves, their angles altered to 8 x 4.5 degrees and 10 x 4 degrees inlet and exhaust respectively. By canting the valves in this way they open toward the center of the cylinder and the 
gases are less encumbered by the shrouding effect of the cylinder wall. The intake valves are increased in diameter to 2.100in and the exhaust to 1.600in.
On pump fuel and barely 9:1 compression ratio, the 302 engine with Kaase P38 cylinder heads, a modest camshaft, and an Edelbrock Junior intake easily generates 500hp @ 7,500rpm.
The P38 operates with slightly altered intake valve pockets on the piston crowns, narrow stud-style rockers, appropriate guide plates, and different valve covers. Optional mounting holes for larger diameter headers are provided as standard.
For printable catalog fact sheet click here.
The P38 uses narrow rockers.
Jon Kaase Racing Engines, Inc.
735 West Winder Ind. Parkway
Winder, GA 30680
Telephone (770) 307-0241
E-mail: JonKaaseRacing@gmail.com
Website at: www.JonKaaseRacingEngines.com
I have a 351 Windsor with KB 136 pistons with a 0.150in dome and am curious as to what head would give me the best bang for the buck: 180cfm or 200cfm. With 0.030in overbore, 30lbs injectors, 4:10 gear, 3550 5-speed, I would like to keep 10:1 compression ratio as I use the car for street-strip use.
Will these fit the Ford 289 circuit engine?
Ernie,
The P-38 cylinder heads would fit any of the Windsor-based engines, 289 and up once you put the proper valve relief in the pistons. Unfortunately, these cylinder heads have been discontinued in an effort to concentrate on our core big block and race engine business.
Discontinued? How do you recommend we find them then?
David,
Unfortunately, since we no longer manufacture them, your only option to find P-38 cylinder heads would be in the used market place.