Camshaft Engineering Company

Proper function and durability of camshafts are dependant on observation of correct fitting and initial engine run-in procedures. The most critical period is the first few minutes of engine operation. One of the highest contact pressure areas in an engine is that between the cam follower and the highest part (nose) of the cam lobe. If not assembled with some form of lubrication of these surfaces, this pressure can lead to metal to metal contact causing a condition called scuffing, which leads to abnormal wear and premature failure of the lobe and follower. Scuffing can be described as the cold pressure welding then tearing of the contact points on a microscopic scale, roughening the surfaces and producing debris which can cause further deterioration of the surface.
All camshafts which run with sliding type followers (as distinct from roller type) ground by Camshaft Engineering are surface treated with a heavy duty manganese phosphating process as initial anti-scuff protection. This still requires there to be a liquid lubricant to develop the normal hydrodynamic film to support the contact forces at higher rubbing speeds.
Some conditions which promote the possibility of scuffing on startup are, low speed rotation for an extended period, additional pressure from non standard valve springs or from springs coilbinding, re-use of worn followers, and lobes and followers assembled dry. As an added safeguard against the possibility of scuffing at first startup, lobes should be liberally coated with specially formulated "cam lube" material.

Assembly of camshafts and related parts must include the following points:-

Cam followers (including rocker types) must be new or correctly reprofiled.

Reground camshafts particularly modified grinds, will have base circle diameters less than standard size. The need for compensating changes to rocker bridges, shims, pedestal heights, or valve stem heights, etc, must be checked and implemented where required for proper valve train operation, especially with non-adjustable valve train designs. For the latter designs, the BCD undersize is advised on the camshaft identification tag, and/or the modified grind data card to assist the fitter. If in doubt, contact Camshaft Engineering.

All lubrication galleries and pipes must be checked as free from partial or complete blockage from degraded oil deposits. Some aluminium overhead cam designs are prone to this problem, and need to be mechanically cleared.

Check that the camshaft turns freely when installed. Aluminium cylinder heads are prone to warpage or distortion which can force distortion into overhead camshafts. This can result in bearing failure or even camshaft breakage. Warped cylinder heads need to be properly straightened then refaced before re-use.

Camshaft lobes and followers must be lubricated with good quality lubricating oil containing anti-scuff additives, or special pre-lube preparations available for that purpose. This is important for overhead camshaft engines, which do not benefit from lubricant throw-off from crankshaft bearings.

For non standard camshafts or valve springs, check for coilbind, and with pivoted followers, check that the lobe to rocker pad contact is within the rocker pad length.

After engine assembly, prime the oil system to fill the oil filter and galleries to avoid delay in oil circulation on startup.

Before attempting to first start the engine, check the ignition and fuel systems to minimise the cranking period before the engine starts. Prolonged cranking of the engine, or low engine speed operation can result in scuffing and subsequent lobe failure.

Maintain the engine speed at 1500-2000rpm to ensure adequate lubricant flow and surface rubbing speeds to develop the required lubricant film pressures. Do not allow the engine to idle below 1000rpm for the first hour or so of operation.

These procedures are even more important on modified or performance camshafts, where the higher lifts induce higher spring forces, even with standard springs.

Finally, it is important to ensure that the engine is regularly serviced, particularly with respect to lubrication change intervals. This applies not only to kilometres travelled, but also to time period. Overhead camshaft designs are critical in this respect. Use only quality lubricant of grade specified by the engine manufacturer. Even then, the additives blended into the lubricants deteriorate over time, such that they lose their protective value. This applies particularly with short trip stop and go driving patterns. Regular changes with the correct quality lubricants is the best guarantee for reliable extended engine service.

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