quote:
Originally posted by PanteraDoug:
... What you pick though depends on what you want the nature of the car to be ...
I'm focused on the word "pick". The word leads a person into the mindset that the only choices are those available off the shelf. I pen my own camshafts, and have since the 1980s, because what's on the shelf doesn't provide what I want. Custom cams allow me to tailor the engine to have the characteristics I want it to have.
quote:
Originally posted by PanteraDoug:
... To reach their full potential Clevelands need more cam than this ...
That term ... "more cam" ... may draw the wrong picture in people's minds. A picture of high overlap, long duration, rough idling, and poor drivability. If that's what "more cam" means then I disagree with that perception.
If we can agree that the production block is more or less good for 450 bhp and 7200 rpm, within that limitation the Cleveland can be quite drivable with the opposite of "more cam" thanks to the performance attainable with modern cam lobes which provide more valve lift with less duration.
I know of a Cleveland producing 440 bhp at 6500 rpm using a 750 cfm Summit carburetor, Blue Thunder intake manifold, GTS exhaust system, 10:1 compression, and the "little" Crane HR-216 hydraulic roller cam. 440 bhp was attained in this case with "less cam".
The specs of the Crane Cam:
Advertised Duration (at 0.004 inch tappet lift) = 278°/286°
Estimated Duration (at 0.006 inch tappet lift) = 270°/278°
Duration at 0.050 inch tappet lift = 216°/224°
Gross valve lift (at 1.73:1 rocker arm ratio) = 0.562/0.586
LSA = 112°; estimated overlap = 50°
I also know of a Cleveland producing 500 bhp at 6500 rpm using IR fuel injection, a bundle of snakes exhaust, 10:1 compression, and the same "little" Crane HR-216 hydraulic roller cam. 500 bhp with only 50° overlap! The additional 60 horsepower of this second engine, using the same camshaft, was the result of higher volumetric efficiency and a better exhaust system. You gotta admit, the HR-216 cam is an unexpectedly small cam for a 500 bhp engine, and 6500 rpm is the lowest peak rpm you'll ever see 500 bhp made with iron heads, stock stroke, naturally aspirated, etc.
For perspective the Pantera teams raced in Europe during the 1970s with 440 bhp utilizing the production block, the iron crank, and a 7200 rpm rev-limit. Ford teams competed in NASCAR during the 1970s with 570 bhp engines utilizing the heavy duty Bud Moore & Tope blocks, fully counter-weighted steel cranks, and an 8500 rpm rev-limit.