Atomic Barra High Rev Lifters | 'Anti Pump Up'

Our anti-pump up lifters were designed in collaboration with Crow cams to have double the bleed off rate of standard lifters. This means they can reliably tolerate beyond 8000rpm. These are designed to be able to take higher RPM whilst reducing wear on the valvetrain. Our lifters can maintain better valve contact and this reduces the chance of valve seperation or valve float which can break valves, rockers, cams and even whole engines.

Maximum preload of .75mm (.030") recommended for street use. Please see instructions for tips on setting preload to within specified tolerance. ALL brands and models of hydraulic lifters should be checked to ensure proper preload. ALL OF THEM! See below for a technical explanation and instructions on checking. 

Excessive preload on a hydraulic lifter or tappet can lead to several issues:

• Valve Train Noise: The lifter will not be able to properly compensate for valve train expansion as the engine warms up. This can cause a ticking or tapping noise, especially when the engine is cold.
• Reduced Lifter Life: The constant pressure on the lifter's internal plunger can cause accelerated wear and premature failure.
• Valve Float: Excessive preload can prevent the valve from fully closing at high RPMs, leading to valve float and potential engine damage.
• Loss of Power: Valve float can disrupt the engine's combustion cycle, resulting in a loss of power.
• Valve Burning: In extreme cases, excessive preload can cause the valve to remain slightly open, resulting in valve burning due to hot exhaust gases.

Explanation

Hydraulic lifters are designed to maintain zero lash in the valve train. They use engine oil pressure to adjust their length and compensate for thermal expansion and wear. When a hydraulic lifter has excessive preload, the internal plunger is pushed too far down, effectively making it a solid lifter. This eliminates the lifter's ability to adjust for changes in valve train length.