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Interesting. What's happening now with the newer roller lifters? I've seen something about this in another thread but couldn't remember exactly what was being discussed at the time. Can you tell more?



We see OEM hydraulic roller lifters holding up well for several 100k miles. But I wouldn’t put that much merit into an aftermarket set in high performance applications. In my view, more moving parts means more moving parts that could go wrong.

Also, the founder of Schubeck lifters warned of using roller lifters that have needle bearings in them likening them to a ticking time bomb. Instead, Joe Schubeck had a roller lifter design that utilized pressurized oil from the motor rather than the needle bearings. That would be the way to go if you wanted to run a roller lifter.

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Next thing. Maybe a little off topic, but what exactly makes a "flat tappet" cam vulnerable now opposed to several years ago. I know the quality of oil has changed and the zinc/phosphourous is way less nowadays (for a flat tappet cam), but what makes the roller a stronger cam that it doesn't need the same amount of zinc? Is the flat tappet cam just weaker? Made of a lesser strength of metal?



Roller lifters have a roller on the side of the tappet that meets the cam lobe. Because of this design, the coefficient of friction is greatly reduced when compared to a flat-tappet lifter which is basically a flat piece of metal that comes directly into contact with the cam lobe which slides over the cam lobe when in operation. As a result, a flat-tappet lifter has no provision in of itself to reduce friction like the roller lifter. This is why flat tappet cams rely primarily on anti-wear additives like Zinc & Phosphorous in motor oil to reduce the metal-to-metal contact friction.