Thread: Please help I am racking my brain on this one.

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Originally Posted by aahx2011

I have run it and adjusted the lifters a couple of times now and still sounds awful.

That's because you've been suckered into buying one of those fosdick, *&%$^%^&^^% piece of !#@$ Extreme Energy pile of steaming dog poo camshafts. It's always gonna be noisy as H%@# all the time it's in the motor and it will fail prematurely. The engineers who concocted this garbage design should be chained to a pole and caned.

Here, maybe this will help you in your valve adjustments later on when you do another motor.....
http://www.crankshaftcoalition.com/w...stment_SBC/BBC

OK, I'll explain.
Many years ago, Harvey Crane of Crane Cams postulated the idea of "hydraulic intensity". This is the work that a lobe does in lifting the lifter off the base circle of the cam to the nose of the cam. You can grind a cam lobe design that will do this work rather easily, as with some of the factory grinds, or you can ask the lobe to lift the lifter quickly, as in the Extreme grinds. Harvey ground most of his cams on a hydraulic intensity of 62 for years and years.

The amount of work that the lobe is asked to do can be seen by subtracting the 0.050" duration from the 0.006" (advertised) duration. A 300/230 cam would have a hydraulic intensity of 70 and would be very easy on all the associated parts. A 300/260 cam would have a hydraulic intensity of 40 and would be asking the lobe to yank the valve open and slam the valve back down quickly. Of course, the valve isn't slammed down onto it's seat, but it is made to unseat and seat itself very quickly and is therefore required to do more work than its lower intensity brethren. This larger "window" of valve open time makes more horsepower because the valve is open longer than it would be with a slower-opening/closing lobe. I have done multiple Dyno-Sims on these cams in relation to slower lobe cams and I can find only about 10 hp on a 400 hp build.

This Extreme design is a competition design, where you might be interested in making another 10 hp so you could drive around the guy who has been running ahead of you forever. The design itself requires that the builder does everything right on the build and then does frequent inspections on the install throughout the racing life of the motor. THIS LOBE DESIGN HAS NO BUSINESS IN A STREET MOTOR.

"If nothing else leads to its downfall, a profile ground on a good core can have a hydraulic intensity of 50° - 55° and be a pretty safe bet in terms of reliability."
David Vizard


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