With our project engine block fully machined and the Butler stroker kit balanced and checked, we are almost ready for preassembly using the myriad performance parts that were provided by Summit Racing Equipment, but that will be covered in the next issue. First, RaceKrafters will attend to our 6X Pontiac head castings.
This installment will be of particular interest to HPP readers, since these are the only procedures that can be applied sans a complete engine rebuild. A Pontiac may have its cylinder heads removed for a valve job, failed head gasket, porting for improved power, or swapping to a more efficient design. Regardless of the reason, all of the steps showcased in this primer can apply.
As is true for block and rotating assembly work, a complete inspection and application of all machining procedures should be implemented. The cylinder head is a paramount component, not only to the engine’s potential power production but to longevity as well—no shortcuts should be taken.
 Once a used head is stripped and visually inspected, it will be cleaned up in the bead
We will showcase through photographs the actual work performed on the mule’s cylinder heads, while the text will expand on those procedures and speak about some others that do not apply to our application. The goal is to educate our readers on the steps required for proper engine building even if in your case you may only be working in one area.
Disassembly, Cleaning, and Inspection
Once the cylinder head is removed from the engine, it’s advisable to tag the rocker arms and pushrods unless new components are going to be purchased. It’s also a good idea to retain the head gaskets and mark them for each side of the engine. Carefully remove them from the block and look for an even imprint on both the cylinder head and block deck surfaces.
Before leaving the engine block, use a thick motor oil, such as a 50W rating, and with your hands or a new, clean paint brush, coat the cylinder walls and deck of the block to prevent corrosion. Securely cover the exposed parts of the engine block with either a plastic trash bag of the appropriate size or with a cling-type plastic wrap.
 It is important to pressure check a cylinder head before any work is performed. This m
The machine shop will do a quick visual inspection of the heads and look for damage, such as cracks and valve-seat recession. When recession occurs, the valve will actually start to pull through the cylinder head at the seat—the surface the valve closes against. The seat then starts to migrate further into the casting.
Once the shop thinks the cylinder head is acceptable, it will disassemble and clean it, and do a more thorough inspection. Cast-iron heads can be magnafluxed using the same procedures that are employed for an engine block and crankshaft.
Cylinder heads need to be pressure-checked using an application-specific machine to confirm that no cracks exist. Aluminum heads can sometimes crack in between the seats for the intake and exhaust valves due to the lack of material in this area and its high exposure to heat. If any damage to either a cast-iron or aluminum cylinder head is discovered, a decision to repair or replace it needs to be made. The cleaning process is usually similar to that of a cylinder block—they can be hot-tanked, jet-washed, or placed in a bake-off oven. Aluminum cylinder heads are not hot-tanked due to the impact the cleaner has on the material.
 Corey installed a plexiglas radius on the intake port for accurate flow bench testing.
Valves will be inspected for wear and to see if there is a sufficient margin left to re-cut the necessary angle and still maintain enough mass for cooling. The margin is the flat surface on the side of the valve head that is just below the face of the head if held with the stem toward the ground. If it’s worn away, then the valve will need to be replaced. If it’s put back into service, it will fail prematurely by loosing its shape and not provide a good seal against the seat.