Each cylinder head core is disassembled and inspected for broken bolts, stripped thread holes and broken mounting holes, etc. All heads go through a three-step cleaning process which includes:
1) Passing through a high temperature oven.
2) Professionally bead blasted.
3) Placement in a non-caustic hot tank.
The Head is then inspected for cracks & pressure tested. Cam bores are checked for spec and honed if needed. Note: No major welding work is ever done!
The machining process includes; ? Inspect valve guide bores using a dial bore gauge and repair where needed.
? New OEM German Phosphorous Bronze Valve Guides & Valve Stem Seals are installed
? All valve seats are cut, not ground, using three angle cuts for maximum precision.
? The valves are inspected for stem and valve face damage and/or wear, as well as straightness.
? All valves are hand ground and/or replaced as needed.
? Thoroughly inspect and test all of the valve springs for proper tension / resistance and replaced as needed.
? All head surfaces are machined (milled), not ground!
Final cleaning and assembly includes; Cleaning all heads in a solvent base tank in which all oil galleries, thread holes, etc. are cleaned. A number of different brushes are used to catch any remaining contaminants. All heads are run through a detergent based hot tank before assembly. All assembly work is done by hand by Professional and Expert Porsche Specialists.