The first camshafts used a solid lifter design. Camshafts of this type were made from a rod and the lobes were welded on. All that changed in 1908, when the first overhead-camshaft designs began to appear. The first hydraulic lifters appeared on Pierce-Arrow motorcars in 1930. In 1940, solid BAM roller lifterswere created for use in America’s fighter and bomber planes.
For increased power and lower friction, most modern production engines employ roller cam technology. These cams are typically made of a single piece. Some are made from induction-hardened steel, while others are made from ductile and selectively hardened ductile. This technology can be applied to high-performance street engines and race engines, which we all know well.
It was the hydraulic roller camshaft, which was quickly recognized as the future of street engine performance. Aftermarket companies quickly flooded the market with new hydraulic roll designs. Modern hydraulic roller and solid-roller lifter designs are far superior to their predecessors. They have advanced designs for the related parts, which reduce weight and friction, giving you more horsepower.
Avoiding rotating BAM roller lifters
The optimization of the valve lifting curve to maximize the engine’s trapped charge is an important part of engine performance. The switch from flat-faced to roller lifters in an overhead valve engine (pushrod), has allowed engineers and designers greater freedom in designing new lift profiles. Sprint Cup is NASCAR’s fastest class. But, even though the engines are equipped with flat tappets (also known as flat tappets), the performance of the engine would be much better if it didn’t ban BAM roller lifters/tappets.
The lift velocity of flat tappets is affected by the size and limitations of the tappet. NASCAR is another limitation. A roller lifter can achieve higher lift speeds and, within a valve event duration, this additional latitude can be utilized to maximize lift and increase the area under the lift angle curve. It’s no surprise that roller lifters are almost always used on passenger cars. The same goes for racing when allowed. Although roller lifters can be more costly and are more complicated, passenger cars have stopped using flat lifters in recent decades.
However, roller lifters can have one disadvantage: the lifter must not rotate within the bore of the lifter to align the roller with the cam lobe.
The flat on the body of the lifter locates on a similar feature on a plastic tray. There is an issue with lifter tray oil collection. Therefore, extra holes are often made to prevent oil from pooling in the tray.
Another option, also known as a “dog bone”, is where a metallic plate is bolted onto the engine block. It is fitted with flats located on the lifter body. Similar to the lifter tray method, the dog bones are smaller than the lifter tray and do not have the oil drain problems that trays suffer. As no reciprocating weight is added, the dog bone provides the lowest possible lifter weight.
To allow an anti-rotation key to slide in the lifter bore, it can be machined. This key is a part of the lifter. It is probably the most compact solution. This key does add some weight to the reciprocating following, however. It requires a more intricate lifter bore.
An alternative idea is to link two lifters onto one cylinder using a loosely articulated link called a tiebar. It’s heavier in terms of the reciprocating mass but it is still a good idea. Although it is a relatively simple component, the reciprocating mass of components on the pushrod side and the rocker are increased by the link. The mass of the tiebar is only visible to each follower. This is because the mass centroid has a lift that is half that of any other valve.