Why Break-In's Not a Crime
A few years ago, the cam companies...
A few years ago, the cam companies stopped selling cams with molybdenum disulfide as a lobe lubricant, instead relying on a thicker assembly lube without moly. This is because that black moly paste is highly abrasive and can damage other delicate engine components. Do not substitute white paste, like Lubriplate, however, since this is not a high-pressure lubricant.
If your engine is equipped with a roller cam, this story really doesn't relate. But because a flat-tappet-style camshaft relies on a follower that slides across the cam lobe, it requires lubrication that can minimize this sliding type of wear. All off-the-shelf oils that have a current API SM rating have had the zinc levels reduced to protect catalytic converters. This is not to say that using the current SM-spec oil will eventually kill your flat-tappet camshaft. There are probably thousands of engines running around right now without difficulty.
There are some mechanical things that could predispose particular engines to wear problems. Excessive valvespring pressure will only aggravate these problems, since these higher spring rates create more load between the lifter and cam lobe. Crane Cams suggests flat-tappet cams not exceed 300 pounds of load over the nose of the lobe. Generally, most street hydraulic cams do not see this much load at max lift, since the open-spring pressure is divided by the rocker ratio. So, if the open-spring pressure is 400 pounds and the rocker ratio is 1.5:1, the load on the lifter is around 266 pounds.
Flat-tappet lifters are designed to spin in the lifter bores. This requires that the lifter bores be free of burrs or casting flash that can cause the lifter to stick and not rotate. Big-block Chevys are infamous for sticking lifters because of their angled pushrods. If you think there is a problem, place a color stripe on the pushrod and watch it with the valve cover removed as the engine runs. If the pushrod does not rotate, the lifter is not spinning.
High-ratio rocker arms also tend to place more load on the lifter and cam lobe. This is because higher rocker ratios open the valve farther, which increases the load between the lifter face and the cam lobe at every point on the lobe. For break-in purposes, you should break the cam in with a shorter-ratio rocker arm and then swap the rockers after the first hour or so of engine operation.
 Dual valvesprings increase...  Dual valvesprings increase the load on the lifter. Do your cam a favor and pull out the inner springs before breaking in the cam. It's extra work but will probably save your cam. |  Here's what happens if the...  Here's what happens if the cam is not broken in properly. These concave lifters are a direct result of poor break-in procedure. This also kills the cam, not to mention the load of metal filings all through your engine. It's not pretty. | |