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8. The 68 A body 383's are identical to the 330 horse B body 383's except for the exhaust manifolds. Both have the same 256/60 cam. Since the A body 383's are rated at 300 horsepower and B's at 330, either the A body exhaust manifolds are 30 horsepower worse or either one engine is overrated or the other is underrated.
9. The 69 A body 383's are identical to the Road Runner/Super Bee 383's except for the exhaust manifolds. Both have the 440 hi-po 268/276 duration, .450/.465 lift cam. Since the 69 A body 383's are rated at 330 horsepower, one would assume that their exhaust manifolds are only five horsepower worse than the Road Runner/Super Bee exhaust manifolds (I can actually believe that).
Problem with that theory is that the 68 and 69 A body 383 exhaust manifolds are the same, so you have to believe the same manifolds are 30 horsepower worse than B body (non hi-po) 383's one year, but only five horsepower worse than the (hi-po) 383's the next. (And of course, 440 A bodies had the same horsepower rating as 440 B bodies, so what's the deal there????)
I too have enjoyed this thread.
I was in the attic looking for skis and grabbed some measurements from the original exhaust pieces from my 68 383 GTS. Head pipe is 2 1/4" expanded to 2 1/2" at the manifold flange. The tail pipe is 1 7/8". I don't know what was on the 69, but maybe this is the reason for the 30 hp rating difference between them.
I see now that JohnRR said that the 69's were small too.
Last edited by BSB67; 01/20/12 08:00 PM.
