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Whats the deal with older L67 cylinder heads?

April 26, 2017cylinder deal Heads l67 Older

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Whats the deal with older L67 cylinder heads?

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Apparently, there was an issue with early L67 cylinder heads being prone to cracking. It appears that the casting was actually changed DURING the 1998 model year. Old castings are G.M. #24503436 and have .855″ valve spring seat pilots. New castings are G.M. #24507848 and have .810″ valve spring seat pilots. You can remove your heads, and have them checked for cracks by a machine shop. Or, you can remove one valvespring and measure the diameter of the valve spring pilot seat. Those are the only ways we know for sure to discern whether or not you have the ‘problem’ cylinder heads.