Again,the only problem with any of this is it's all theory. No hard numbers on the engines in discussion to back up the info.
From my basic measurements on several stock GM 235-261 cams I see the exhaust lift is about .010-.020 higher than the intake.Looking at the repair manuals,stock cam exhaust timing is about 12-20 degrees longer than intake at advertised duration.No secret that inlines have restrictive exhaust and intake systems .
Now,once the engine is modified with a better exhaust and intake who knows what really goes on.McGurk famous dyno test of the 261 was using a 54 Vette dual exhaust manifold.I would think a typical set of Fentons may flow better.Or of course what effect does a tuned steel tube header have?
Flow bench work needs to include the intake system to get a true idea of actual flow.
