If you haven't heard the jungle drums rumbling, the life of your flat-tappet hydraulic camshaft may be in danger. But with a few careful steps and some attention to detail, you can avoid the killer of innocent camshafts FLCS-flat lobe cam syndrome. Just follow our lead.
Over the past couple of years, the Detroit Big Three have been lobbying to lower the levels of the antiwear agent zinc in motor oils. It seems that after engines get a few miles on them, it's not uncommon for some oil to be burned in the combustion process. The zinc dialkyl dithiophosphate (ZDDP) additive creates an ash when burned that is apparently very good at coating oxygen sensors and the active substrate in catalytic converters, reducing their performance. Since virtually every late-model production engine uses roller tappets, the American Petroleum Institute (API) has lowered the ZDDP levels in motor oils listed as meeting the current SM oil rating.
Pressure-lubing an engine before initial startup with a new flat-tappet cam is absolutely necessary now to prevent flattening a cam lobe or two.
Why is this important to a typical car crafter with a flat-tappet camshaft and no catalytic converters? This same zinc additive is a wonderful antiwear additive for sliding-follower, flat-tappet camshafts. Before you panic, the zinc has not been removed, but the levels are far lower than with older oil configurations. As a result, aftermarket cam companies are seeing an increasing number of flat-lobe problems.
If there is one period of time when a flat-tappet hydraulic or mechanical lifter cam is most susceptible to severe wear, it is during the first 20 to 30 minutes of camshaft operation. This is when the lifter and cam lobe create their initial wear pattern. If sufficient high-pressure lubricants (like zinc and phosphorous) are present during this break-in procedure, the camshaft has an excellent chance of survival. We'll go over the details of how to properly break in a flat-tappet cam and which oil to use to ensure the cam doesn't fail a few thousand miles down the road.