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Discussion Starter #1
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.

Scott
 

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Does this apply to the L36 as well? Do the L36 and L67 share the same head design?
 

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Hi. I have a 1997 Camaro 3.8. It had about 85,000 miles when it cracked a head. I maintained it flawlessly as well..well..since I bought it used with 73,000. Still, a head cracking before 100,000 seems a bit premature to me.
 

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My apologies..... previous posts before mine were made on October 7th of 2004.... I failed to read the year, sorry for resurrecting this one.
 

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Discussion Starter #8
Old castings are G.M. #24503436 and have .855" valve spring seat pilots.
These older heads with the larger valve spring seat pilots are the same ones that won't accept the LS6 valvesprings.
 
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