quote:
Originally posted by Otis:
... Hi guys I just purchased #6243 and have been enjoying the car for just over a week now. It has been a blast, however I was expecting a little more considering what I was told of the engine ... Anyways let me know what you think, if the intake is fine or if its time to upgrade ...
Congrats on the purchase, welcome to the forums.
What do you mean you were expecting a little more? In what way is the engines performance disappointing?
I am in agreement with those who have advised making sure the carburetor and ignition are tuned properly before going any further. If the carburetor isn't calibrated properly for that engine, and you install a new manifold but reinstall the same carburetor, it still won't be right. For now the manifold is fine, it is not an obvious problem.
quote:
Originally posted by PanteraDoug:
... the Shelby intake ...
There is a dual plane 351C manifold that was sold by Shelby beginning 1970 through about 1974, and has been manufactured by Blue Thunder (AT Francis) since the early 1980s. It was actually designed by Ford engineers (Ford owned Shelby back then). That's the manifold Doug refers to.
My experience with this manifold includes manually shifted cars and spans 4 decades. I think its a great manifold. Its a bit of an anachronism these days (like me), its been around since 1970, technology has marched forward in the last 44 years. You look at the big ol' runners and its hard to imagine it doesn't impact low rpm performance ... but it doesn't. Compared to the factory manifold the transitions are smoother, and the pinch points are opened up. The newest dual plane manifold for the 351C is the Edelbrock RPM Air Gap manifold, which is a high rise manifold with a cut-down plenum divider. Block-off the exhaust heat passages of the Blue Thunder manifold and it will run shoulder to shoulder with the Edelbrock RPM Air Gap manifold (which has no exhaust heat capability).
I'm sure "porting" the Blue Thunder manifold can improve that performance a bit, in other words pick up a few extra horsepower; but the manifold performs very well right out of the box. It doesn't affect the lower rpm power or drivability, it gives a harder hit in the mid-range, and it makes the engine more willing to rev at high rpm. I think its absolutely wrong to give the impression the manifold is a "dog" out of the box, performing well only after it has been ported. Every batch of those manifolds sell out quickly at more than $400 each, and I hear an abundance of positive feedback from the buyers. It has been a well liked and well respected manifold for decades.