Granatelli Motor Sports Crafts Beautiful Billet Valve Covers

EngineLabs looked at how Granatelli Motor Sports machines its billet valve covers in a September 26, 2013 story by Jason Reiss. The story was also carried by sister site Chevy Hardcore. According to the article, Granatelli Motor Sports was adding CNC equipment and staff at its GMS Australia facility to build the covers.

Why SB2 Covers on an LSX Build

The article ties the covers to a 400-cube LSX engine under construction at Late Model Engines in Houston for the BlownZ project car. That engine uses Edelbrock LS-R heads modified by Curtis Boggs at Race Flow Development, and unlike other LS heads, these castings share the SB2 valve-cover footprint. Granatelli Motor Sports already made billet covers to fit it.

Machined in One Continuous Program

EngineLabs explains that each cover is cut from a solid block of 6061-T6 aluminum on a CNC turning center that runs the whole job without operator input. J.R. Granatelli told the magazine, "If you look at the top or the bottom, there are no pickup marks where you can see the machine stop."

According to the article, the mounting holes are drilled first and used to index the rest of the work. The machine hollows out the underside, flips the cover and finishes the top in the same run. The designs start in Pro Engineering (Pro E), are exported as CAD files and are then loaded into a Haas CNC machine.

Features Beyond Looks

• Optional integral valve spring oilers with removable jets, intended to help keep spring temperatures down
• Steel inserts in every mounting hole to protect against overtightening and wear from repeated removal
• Custom logos machined into the top of the cover rather than printed on
• Ribs on the underside that keep the top from being pulled in by a strong vacuum pump or pushed out by heavy boost
• A thick gasket rail that adds strength where the cover meets the cylinder head

The article says those ribs also help stop the top of the head from flexing under boost. J.R. compared the effect to an upper cylinder head stud girdle and said Duttweiler and Lingenfelter used the covers on their high-boost engines.

Read the full article at EngineLabs

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