Years ago I had a conversation with Dave Bisschop regarding static compression ratio on aluminium heads. He felt you can't protect all of these engines once they leave your shop so he often purposely kept it conservative for most that don't want (or shouldn't) push the envelope and stay on top of the tune, bad gas, weather, etc.
In that conversation with conservative in mind and regarding Edelbrock cylinder heads. Based on his dyno testing at the time, he stated 10.25 max for Edelbrock 87cc castings and 10.5 max for their 72cc castings. The difference being the chamber depth between the two. This was his opinion with the chamber design of the Edelbrock round port heads at the time. Not the newer "heart shaped" design.
Edelbrock heads with a revised combustion chamber design and the KRE D-port heads design it's a different story and a higher compression can be run.
Article that might be of interest:
How combustion chamber design relates to engine performance
https://www.motortrend.com/how-to/02...stion-chamber/
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 )
Old information here:
http://www.hotrod.com/articles/0712p...tiac-trans-am/
Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine)
Best time 5.13 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension
https://www.youtube.com/watch?v=qDoJnIP3HgE