imho, that cam has lobes that are not pointed enough for flat tappets. Flat tappet cams have a very pronounced teardrop shape.

 

Is that the spring pressure for the lift of your cam? If so, that is a ridiculous amount.

 

I never said it was a flat tappet cam. I was commenting on the strength of the material the core was made from fellas. Case hardened cast iron is suited pretty well to a mild flat tappet application, BUT it has no business under a roller with the high loads and the very small contact area of a roller lifter. It will fracture as the number of loaded cycles increase. You can see it for yourself, the thing failed right where the spring pressures (stress) is highest.

Combine that with comp doing absolutely everything as cheaply as possible, and you get a core that is probably not up to spec on hardness that would be marginal even if it was. What you get in the end is a failed camshaft and a messed up engine.

 

It's always good to put a filter magnet on the oilfilter in cases like this. They help trap a lot of metal from engine wear in the filter, and it dont matter what car stock or modified all engine wear.

Summit filter magnets: http://store.summitracing.com/egnsea...=KeywordSearch

 

Did you bother to read the post?
There are millions of cast iron cams. in use, so I doubt this has ANY bearing on the problem. And why would a flat tappet cam. have less wear problems then a roller???

 

Yes there are alot of cast iron cams in use. It is my opinion that they are **** poor as a roller cam. Especially with comps doing things south of the border now and pathetic heat treatment process control record.

The difference between a flat tappet and roller lifter is all in the interface and the way the cam is designed due to different constraints.

The roller lifter has very high rates of acceleration, and a large amount of thrust loading (cam lobe tries to shove lifter through lifter bore wall). This increases stress a good amount over pure axial movement.

The interface of a flat tappet lifter is what we call a roll/slide linage in mechanics. The lobes are ground on a taper and the lifters have a crown. So when the cam rotates, what you get due to the taper and the crown and the geometry that results from the interface, the thrust is translated into rotational motion (it also keeps the cam pushed back as a "freebie"), although there is still some thrust load it is very small.

The other big thing, is that roller cams usually run more spring pressure. And you say but wait +100lbs of spring pressure is going to cause that much of a problem? Yes, it is. Think of it in terms of lifter contact area, assume it to be constant between the two types of interface, and assume rocker ratios constant. What you're left with now is force applied by the spring. So if you go from the usual 280-300lb flat tappet spring up to a 380-400lb hydro roller cam spring, you just put a 30% increase in load on the cast iron core. I am not going to go into the math, but when you increase the stress on a part there are a few different regions it will fall into statistically for life expectancy. If your stress level on the part is below a certain threshold it will last indefinaitely. However, as you increase the stress toward the maximum the part can take it can handle far less load cycles until failure.

I avoid worrying about any of this by just pulling an extra 50 spot out of my pocket and getting it on a billet core when it comes time to pay for a cam. If a cast roller cam does fail, and all it costs you is a set of lifters you still lose because they cost more than it would have cost to use a propper core in the first place.

 

If you have a legitimate problem with Comp Cams quality control, that's fine, but that does not equate to all thing cast or built out side the U.S. being crap.
Amazing, you get most of the details right but come to a completely wrong conclusion. The roller tip almost eleminates the thrust loading on the lifter not the other way round. It's the flat tappet lifter that has the higher thrust loading caused by the side forces created by the cam lobe pushing on the lifter directly.
"Think of it in terms of lifter contact area." Good idea! The contact area between the lobe and lifter on a flat tappet cam is very small because of the convex shape of the lifter base and the angled grind of the cam lobe, as you pointed out. The cam lobe literally contacts lifter on only one side, where as, the roller lifter and cam lobe, being ground parallel to each other, make contact across the entire lifter roller. So the roller cam lobe experiences LESS stress then the flat tappet cam, not more.
This is why you can run higher spring rates and more radical cam profiles with a roller cam. This is also why roller cams don't have a brake in period like flat tappet cams do and why it's not necessary to run high phosphorus & high viscosity oils with a roller cam.
Your assertion that there is an increase in stress at the lobe/lifter interface is not based in fact. Nor is your assertion that the cam material is reaching it's stress threshold.

 

This maybe of some help. http://www.cranecams.com/?show=reasonsForFailure

 

You win.

I have spent all the time and energy on this I am going to.

Let me ask you though. If the roller on the end of the lifter contacts the lobe on an angle rather than one parallel to the lifter body centerline. You then end up with an X and Y component rather than a pure Y force. What happens to balance out the X component of that situation if its not the reaction from the lifter bore?

 

It's not about winning, it's about providing correct information. I can't tell if your trying to convince me or yourself. As simply as I can put it, the forces acting on a roller lifter are simply less.
Excerpt from Super Chevy Mag.:
Excerpt from Chevy High Performance mag.:
Excerpt from another article.:
Excerpt from Crane Cams. Site.:
The only difference of opinion here is how much reduction is achieved. All agree that there IS a reduction of forces using a roller cam.

 

I am plenty convinved, what you have posted about flat tappet lifters is not incorrect, but is a product of the forces required shear motor oil, and friction from rotating the pushrod and lifter. Yes that will affect power more force more distance traveled at that force per unit time, you got it no doubt.

What I am talking about is a statics problem (dynamics really but lets keep it easy) that will show the actual load placed on the surface of the cam lobe and where it comes from, it has nothing to do with friction really.

Neither of us are wrong, we are just talking about different subjects.

Or, I will say I am wrong, I really have no more interest in going on with this.