[Alan Roehrich]

Mike,
Actually, using Schubecks to break in a camshaft is the ideal situation, because the Schubecks will burnish and polish the camshaft. You will, of course, need to follow the usual lower spring pressure, 2500-3000 RPM for 30 minutes break in procedure as you would for a regular camshaft, using molydisulfide break-in lube on the cam lobes and lifter faces, with a good quality break in oil.

Trend Performance tool steel lifters do have a hard face (62-64 Rockwell), and a good polish.

Trend Performance tool steel lifters can be refinished, so long as the crown on the lifter face remains intact, and the surface has not been damaged by any failures.

The refinish process is required before using the lifters on a camshaft other than the one they were originally broken in and used on.

The toughest combination is probably going to be an 8620 billet core cam with a tool steel lifter. The reason being that the closer to moving parts with a sliding interface come to being made of a similar alloy, the higher the risk of galling. Fortunately, 8620 steel, commonly used for camshaft cores, is not truly close to being identical to H-11, H-13, or M2 tool steel.

Trend strongly suggests using a DLC coating when using tool steel lifters on an 8620 steel core camshaft. This increases the cost by a substantial margin. They also want you to upgrade from the Premium (entry level) lifter to the Elite lifter, also a substantial increase in cost. After dealing with an entirely different lifter supplier (NOT Trend Performance) I have little use for, and a great distrust of DLC coatings. DLC can come off, and if it does, it behaves just the same as the ceramic on a Schubeck lifter, it destroys everything it touches. Do not take that as reflecting on Trend Performance lifters, I have not used nor sold their DLC coated lifters.

NEVER use DLC against any cast iron cam core. The resulting failure is spectacular, and catastrophic. Cast iron is abrasive, and it will remove the DLC coating, it is just a matter of time. And that information comes directly from three of the largest and most reputable DLC coating companies.

Competition Cams offers a plasma gas nitriding service for their camshafts, it is an excellent upgrade for durability. It is not the same as the old GM "tufftride" process which GM used on severe duty forged steel crankshafts, but it does result in a similar surface hardness increase over untreated metal. This hardness tends to reduce the possibility of other metals sticking to that surface. They also offer micropolishing, and the next step up, their Xtreme surface finish enhancement (specifically intended for steel on steel applications, such as a tool steel lifter on a steel core camshaft).

A harder surface will, as mentioned above, resist the tendency of other metals to stick, or "microweld", or "friction weld" to that surface. Also, harder surfaces are easier to polish, and will also polish to a higher/finer finish, which also reduces the tendency for galling or sticking.

Cam to tappet clearance is something else entirely, and not something to be changed without serious thought and knowledge. A "hydraulic" lifter lobe is designed to be run with zero lash. It really has no "clearance ramp" to take up the clearance between the camshaft lobe and the lifter face commonly called "lash", and as such any real clearance can result in an excessively harsh take up of that clearance. A "solid" lifter lobe does have a clearance ramp designed to take up the lash gently. The lash spec given with a given cam lobe is directly tied to that clearance ramp. If you go too far from that spec in either direction, you significantly alter the characteristics of the lobe in general, and the clearance ramp in particular. That is not a move to be taken lightly. Too little or too much lash will result in the clearance being taken up on a part of the lobe not intended for that purpose, and can result in an early failure of the cam and/or lifter. This applies to both flat tappet and roller lobes. If you are varying your lash from the spec by a significant amount, you really need to be talking to your cam company rep, and he better be really sharp on cam design.