Butler uses Comp XE lobes and for the most part SD Performance uses Comp High Lift Magnum lobes. The XE lobes have shorter seat timing.
Similar conversation here:
https://forums.maxperformanceinc.com...d.php?t=849037
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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)
5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension
https://www.youtube.com/watch?v=qDoJnIP3HgE