Just throwing this in the "Cam Cauldron" ... Running 525efi cams making 600hp on iron headed 555s. Last run is this weekend. Useable HP is 5200 rpm and less. Do I keep the cam and go with roots air cleaners or try diff cams to gain usable hp into the 6k range. My gut says boost is my friend but XRs and 5lbs of boost before have said different.

Well being that manufacturing is my area of expertise, I think the fastest way to make a cam is rough the profile an a 4 axis CNC vertical mill then finish grind. Just my .02 worth..

Heres a informative post from a different site, from Kip Fabre from Cam Motion.

Most people here want aggressive cam lobes. Why? Because someone told them they are better. So what is an aggressive cam lobe? To take the most advantage of the LS Chevy engine design the cam lobe must be smooth and stable. Generally in this LS Chevy engine, the smoother and more stable the cam lobe, the more power and RPM capability the engine will have. So generally the less aggressive lobe will make for the most aggressive (powerful) engine.

There is no need in having 8 different lobe styles or variations for the LS Chevy hydraulic cams. Most of the engine combinations I see on here run from idle to 6500 RPM with a valve lift from .550” to .650” lift and with spring seat pressure 130lbs to155lbs with 350lbs to 400lbs open pressure. The measurable differences in these lobes are very slight, the real difference is that some of them operate very well and others do not. The “hard” or “aggressive” lobes may make a small amount more vacuum at idle and may show a two pound gain in torque at 4000RPM but will cause more valve noise and float the valves sooner plus having a destructive affect on valve train parts and valve seat sealing. The “softer” lobes will have a little less vacuum at idle but provide quite valve train operation and extend the valve “float” RPM 300-500 RPM and do not destroy valve train components.

What do you call “aggressive? Is it high acceleration or high velocity? Which is harder on the valve train? The cam with higher lifter acceleration rates will be harder on the valve train.

Let us compare technical data on two lobes both with 230 degrees duration at .050” with .350” lobe lift. One lobe we’ll call “hard” the other “soft” even though I don’t like to use the word “soft”, but it is soft compared to the hard lobe. I prefer to call it the correct lobe for your engine.

Compare:

HARD SOFT

MAX ACCELERATION: .00037 .000323

MAX VELOCITY: .0073 .00775

NOSE ACCELERATION: .00023 .000212



So which one is more “aggressive”? The soft one moves the valve FASTER or higher speed. So what is aggressive? One of the reasons the hard lobe floats the valve sooner is because it has higher “nose” acceleration, which is negative acceleration at the top of the lobe.

Someone came up with this statement and it stuck, “THE MORE AGGRESSIVE THE RAMP RATE, THE MORE OVERALL AND UNDER THE CURVE POWER”. It was probably some cam lobe designer trying to BS people. Ramp rate? What is that? Velocity? Acceleration? Degrees from .006” to .050”? You must have high acceleration and jerk to have a lobe that has a low .006” to .050” number like 49 degrees, and that will beat the snot out of the lifters and be noisy. We use a smoother ramp of about 55 degrees. The .050” to .200” can be pushed if you want a high duration @.200”, but you will have higher accelerations before and at the nose which will float sooner. If you have two cams, both having [email protected]”, one with .340” lobe lift, one with .360” lobe lift, the lobe with the higher lobe lift (.360”) will always have a higher .200” duration.
Why does everyone want to know the .200 number? because some said the higher the .200 number the better the lobe? Or is it more power it will make?

So, is it safe to assume, as I was saying earlier, that going with a larger lobe lift, of equal duration, will lead to valve float at an earlier rpm? And possibly be hard on parts? What would one do to deal with this scenerio? Throw lots of spring at it is my guess. Probably why some cams need the high rev series of the morel lifters, and nearly 600lbs of open pressure on a hydraulic so it doesnt float at 6200RPM, stiff pushrods, girdles or shaft rockers, , and a different cam, wont float the valves, with 450lbs of open pressure, and run just fine with stud mounted rockers and .080 wall pushrods.

I am curious to see the long term life of my setup, .680 lift and high spring rates.... I keep thinking back to how good my old setup ran especially for the hack work it was, cam and valvetrain never had issues.... made more TQ also..

My Buddy spent 15k last year rebuilding his motor (not blown up). Pretty much the best of everything in the motor. Motor was dynoed before the rebuild and after on the same dyno. Motor made little more then 200 more horsepower and lots more torque all through the power band. Put the motor in the boat and the boat didn't even pickup 1mph. Year before it ran 95 this year the boat ran 95. Kind of a big let down after all the talk (months worth) of the boat running 110+.

Yes so that being said I could have saved 20,000.00 in parts and just redid my short blocks or next time consult a person that builds engines daily and knows boats, my machinist wanted me to stick with 565 cubic inch and smaller cams, he was all for the quality of parts I used, but let's face it the results would have been better if I listened to him... Or the same speeds but save that 20,000.00 in parts

I am gonna dyno to see where things are but I don't expect to gain much if any speeds I did get carbs dialed in and saw decent speeds one engine is down 200 might be a prop issue though. They were even last month with a buddy's props

Here you MT: http://www.superchevyperformance.com...p/88958663.htm

Ah, forget it. It eems as it is a 'go, no go guage' for 1.5 rocker arms. Thought I found something cool.

Cam on the right has an aggressive lobe profile, 60mm

Ok guys lets get this back on topic. I am looking for bulletproof reliability, not something that eats parts on a regular basis.. I built a 396 years ago with the L88 cam and it loved stamped rocker arms... The problem was the triple springs were just too much for the rockers... Enough with the ancient history!!

So back to the original question. I am looking for suggestions and comments for a cam, for my 540 build.

Parts I already have;

Dart big M block 4.500 bores finished
Scat 4340 forged crank
Scat 4340 H beam rods
AFR 335 heads CNC ports and chambers
Mahle 10.5 c/r Pistons ( for sale )
Morose dry sump pan ( for sale )
Milodon gear drive
CMI headers from HP500EFI

Proposed
Crane 741 cam
Inconel exhaust valves
EZ EFI 2.0
Intake is still open to discussion
9-9.5 cr pistons

Operating
up to 6000 rpm.
Rev limiter likely set at 6250.
87 octane is a must.

Looking for 600-650hp and about the same for tq.

I think that covers it, reliability is job one. This really is a mild build for the rotating assembly so it should live a long time.