Lifters

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Producing Quality Computer Tools for Racers and Engine Builders since 1986

What is a Lifter?

Valve Train - Image courtesy of openticle.com

A lifter is a cylindrical component that rides on the Cam Shaft to actuate the Intake and Exhaust Valves. For pushrod engines, the Lifter pushes the pushrod up into the Rocker Arm and opens the valve. For OHC (overhead cam) engines, the lifter pushes directly on the valve tip.

Solid Lifter

Solid Lifter - Image courtesy of starperf.com

A Solid Lifter or Mechanical Lifter is (as the name suggests) is solid. It is basically a solid metal cylinder. This means that the Valve Clearance needs to be adjusted periodically. These lifters are usually used in racing applications because they keep their tolerances and work well with higher valve Spring Rates. But on the down side, they take longer to get set up properly, require you to adjust the Valve Clearance periodically and are more noisy because of the Valve Lash (meaning the lifter will slam into the rest of the valve train and cause a slight clicking noise).

Hydraulic Lifters

Hydraulic Lifter - Image courtesy of buyspeedparts.com

Hydraulic Lifters were introduced in the 1950's as a way to make mass produced engines quieter. They use oil pressure to minimize the Valve Clearance. They have a small hole in the side of the lifter so the oil pressure from the engine will fill up the lifter with oil and put pressure on the valve train. This doesn't eliminate Valve Lash but it does reduce it to about .006 inches. These lifters are usually used in mass produced vehicles because they require less maintenance and drastically reduce engine noise. But these lifters do have a significant drawback, they can loose pressure at high engine RPM's reducing the lift of the valves, or can become "over-pressurized", actually becoming too big and can prevent the valves from seating. This condition is called "lifter pumpup".

High Leakdown Hydraulic Lifters

Some hydraulic lifters are designed with a higher leakdown rate. What happens is that at low RPM, where there is more time for oil to leak out and oil pressure is typically lower, the hydraulic lifter has an effective lash of .020-.040 inches, reducing effective Duration and overlap. This helps idle quality and lower RPM performance but produces valve train noise and can be harder on valve train components. At higher RPM, they act more like typical hydraulic lifters with only .006" lash. It's kinda like a "poor man's variable valve timing".

Roller Lifters

Roller Lifter - Image courtesy of ws6project.com

Roller Lifters have a roller on the end that rides on the cam shaft. This reduces valve train friction and allows for a power increase. Roller Lifters also allow for greater lifter velocities and more lift providing for more lift and duration to help high RPM "breathing". Plus they allow for higher higher valve spring rates for increased engine RPM's with little consequence to low RPM power and drivability.

They are more expensive than flat tappet lifters but they last longer and in some situations they can be reused if you change the cam shaft.

Programs that take Valve Lash into account

We have 3 programs that work with Valve Lash when conducting Engine Simulation: Engine Analyzer v3.4, Engine Analyzer Plus v3.4. and Engine Analyzer Pro v3.9.

We also have 5 other programs that take Valve Lash into account when making calculations. Cam Analyzer v3.8, Valve Spring Tester v1.1, Port Flow Analyzer v3.5 with Valve Opener and Engine Log Book v1.1.