Quote Originally Posted by Itoldyouso View Post
It seems to me we are hearing more and more about flat tappet cam failures than we ever did in the old days, even when the cam is broken in properly. I know we hear about oil today "not having the good stuff anymore", but sometimes cams fail even when additives are put in to replace some of those things.

Before I knew what I was doing (not that I know much more now) I remember installing a lot of cams in Pontiacs, Fords, Chevys, and other engines without even doing a breakin procedure, I would just install it, fire it up, and let it sit there and idle for a while. And yet, I don't ever remember one of them wiping out a lobe.

Are cams made of different metals now, or are we using higher spring pressures or more lift, which is affecting how they rub the lifter base? Just curious what our more educated members think is causing this to happen.

Don
Don, as you know, the oil producers ceased adding extreme pressure lubricants to off-the-shelf motor oils because the additives were affecting catalytic converters and costing OEM auto manufacturers big money on warranty claims. These extreme pressure lubes were necessary because of the tremendous pressure generated at the lifter/lobe interface, some say the pressure there is in the vicinity of 250,000 lbs per square inch. So, that's strike one.

The second thing to come along is the extreme energy grinds, where the lifter edge is just short of digging into the cam lobe as it comes around to nudge the lifter up in its bore. This design adds tremendous pressure over the previous long-ramp designs.

Third thing is the increased use of higher ratio rockers. Even if an extreme energy design can be made to work with controlled spring pressures, oil additives and proper break-in, along comes Ricky Racer looking for that additional 1/2 percent increase with high ratio rockers. This adds more pressure at the lifter/lobe interface, the highest loaded area in the motor.

Fourth thing that I see is inferior materials, particularly from the Chinese. Their castings are not what we Americans are used to seeing and their machining operations are....less than ideal.

I see that Comp in particular is pushing nitriding of the cam before purchase at their store. I'm told this adds to the life of a flat tappet camshaft.

Personally, I will never again use a flat tappet cam in anything I build. I have reached the age of patience, so if it takes a little longer to save up for a roller cam, that's the way it will be.