Re-organize Prep2 Cylinder Head Rules for Clarity & Consistency
#27661 from Production Committee · Rule change · TB 19-12 (2019-12 Fastrack)
In Production, GCR section 9.1.5.E.2.e, delete section and replace as follows:e. The Cylinder Head can only be modified:1. To install an alternate camshaft, and/or adjustable cam gears.2. To port match on the port mating surface to a depth of no more than one inch.3. To facilitate the installation of permitted alternate components, provided the modification serves noother function.4. To achieve the maximum specified compression ratio by the machining of the deck surface.5. To completely plug the holes resulting from the removal of EGR valves and air nozzles. The plugs must
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serve no other purpose.6. To completely plug the stock fuel injection ports in the cylinder head, if the stock fuel injection isremoved and carburetors are utilized. The plugs must serve no other purpose.7. To utilize O-rings to replace or supplement a cylinder head gasket.8. To fit valve seats. Valve seats are unrestricted. Valve seat angles are unrestricted. The valve seatinsert can be no taller than one half inch.
"e. Cylinder Head
1. The cylinder head may be modified to allow installation of permitted alternate components, provided
the modification serves no other purpose.
2. Valve seats and valve seat angles are unrestricted. The valve seat may be no taller that one half inch.
3. The cylinder head deck surface may be machined to achieve the specified compression ratio and to
allow the installation of o-rings to replace or supplement the cylinder head gasket.
4. Holes resulting from the removal of EGR valves, air nozzles and fuel injectors (if the stock fuel injection
system is removed and carburetors substituted) may be plugged, provided the plugs serve no other
purpose.
5. Cylinder head ports may be matched to the intake manifold to a depth of no more than 1 inch from the
port mating surface."