Mechanics

Lifter-Tappet-Follower

This article we will explain the two differences between lifter-tappet and follower configurations present in the automotive industry.


Roller Lifter

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 mileage.

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 - Engine Misfire Visit - Abnormal engine noise


Cam Follower

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.

AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-09-13)