Lifter-Tappet Cam Follower
There are two kinds of camshaft, lifter-tappet, follower configurations used
in ethe automotive industry: IBC (In Block Camshaft) and OHC (Overhead Cam). IBC
has been used since the early years of the automotive industry. This type of configuration
uses a centrally located camshaft (in block) with lifters and pushrods that open
and close the valves in the cylinder head(s). Lifters follow the cam lobes which
dictate how far the valves opens (lift), and how long they say open (duration).
Lifters come in different configurations such as; solid, hydraulic, roller, mushroom,
all of which work on the same principle. Solid lifters have no hydraulic cushion
and rely on the valve lash (air gap) to be manually set at the head of the valve
as it contacts the rocker arm. These lifters are used in racing applications where
higher engine rpm and long durations can damage normal hydraulic lifters.
Mushroom lifters work on the same principle as a regular solid lifter, the difference
being at the contact point where the lifter rides on the camshaft; a regular solid
lifter is the same diameter as the machined hole it rides in, whereas the mushroom
lifter are considerably larger at the contact point to accommodate very aggressive
cam profiles for sustained high rpm racing applications.
Roller lifters are exactly as the name implies, they are designed with a roller
wheel with needle bearings that rides along the camshaft, these lifters reduce the
drag from friction on the mating surfaces as well as being able to handle aggressive
cam profiles. Roller lifters are found in most production vehicles due to the efficiency
of their operation, this helps reduce engine drag, which increases performance and
Hydraulic lifters are found in most production engines. These lifters use oil
pressure to maintain a specific amount of tension on the pushrod/rocker arm to avoid
manual adjustment. When a lifter fails it can cause an engine misfire and abnormal
noise in the engine. Visit -
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Cam followers are used in OHC engines where the camshaft is located above the
valves. The followers are trapped under the camshaft between the valve and the camshaft.
Other camshaft followers are more like a lifter that rides directly under the camshaft
in a machined hole and use oil pressure to maintain the correct lash that eliminates
the need for periodic valve adjustments.
If a lifter or cam follower needs replacement always use a high quality OEM parts.
Less expensive lifters or followers can flatten the camshaft or not mate properly
with the valve train components causing the camshaft to fail.