Originally Posted by 63mako

A lot of you are missing the real issue. Reduced Hydraulic intensity numbers are the main reason more cams are failing. A roller cam can have a fast ramp as shown in the graph above. Actually a better graph woul have the duration @ .050 aligned and the area above the curve and lift would show up much higher in the roller cam. Modern cam designers are trying to achieve a profile close to a roller cam on a flat tappet cam because of the advantages in power, off idle response, broader torque curve, better vacuum. This requires a faster ramp. I have read a couple articles about this, one by Harvey Crane, the other by David Vizard. While neither one really points the finger at this David Vizard does reference that this is an issue. If you want roller cam performance use one. If you want to use a flat tappet check the duration @ .050 against the advertised duration. Factory flat tappet cams had a hydraulic intensity of around 70. If the duration @ .050 was 230 the advertised duration would be around 300. Modern profiles are much steeper ramps to give you the above noted advantages. David Vizard says that a hydraulic intensity of 50 to 55 is the smallest recommended "safe" intensity for a flat tappet. The Voodoo cam the OP referenced has a duration @ .050 of 241/245. The advertised duration is 284/292. This is a hydraulic intensity of 43. This is roller cam intensity in a flat tappet. This is beyond a safely engineered hydraulic intensity. I am not picking on Lunati. All the manufacturers are designing these type of lobes. They have to compete. The customer wants it, they build it. This combined with lower zinc levels in oil. improper break in, incorrect spring pressures, bad geometry and the customers using that new power has lead to the failures you are seeing. Actually the cam cores of today are far superior to the originals in the C3.

http://www.harveycrane.com/duration.htm

http://www.enginebuildermag.com/Arti...r_failure.aspx

Originally Posted by Spot Rot

And I worry if just one of little aftermarket connecting links lets go and a roller lifter turns, it will almost certainly ruin my numbers-matching block.