Turned out the VVT cam advance retarded the cam a full 25* eating up clearance - must have been just just touching - no permanent damage. Root cause is bad machining by the cam grinder - they got the 2 oil passages reversed in the cam from the head pickup to the VVT phaser.
Last edited by efi-diy; 07/10/1112:07 AM.
51 GMC 4.2 turbo Can't solved today's problems using the same technology/thinking that created them
