Re: 67 ZL1 ?
 

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What are those marks on the deck above #3 and #7?

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Notice those cylinders are the ones where the "extra" head bolt(s) were intended to go (no provisions for bolts in those locations on a standard pass. car block, they were added for race applications--note the bosses in the lifter valley where the fasteners would go into the bottom of the head)

Since this was a very common location for a head gasket to let go if the "extra" head bolts weren't used, some racers dimpled the deck here in an attempt to give the head gasket something to bite into to prevent them from blowing out.

Re: 67 ZL1 ?
 

We haven't used the extra bolt holes on the ZL-1 engines that we've built in the past. No need to if the engine is built right with the correct head gasket. We dyno all ZL-1 engines that are built a CHP to make sure there are no issues.

Jerry

Re: 67 ZL1 ?
 

http://www.guinns-engineering.com/Pa...type%20ZL1.htm

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Nikke