| It's the same technology as all cars are using from the 60's on.. There is a Little Pancake Cylinder built into the Cam Bucket or Lifter. Engine Oil Pressure will come into that Cylinder and push it up against the Cam Base Lobe.. When the Cam Lobe starts to Push the Bucket Down, the Inlet port of the Pancake Cylinder gets Closed by the Oil Trying to come back out.. As the Bucket and Pankcake are lifted by the Lobe, the Lifter acts like a Solid Piece.. After the Lobe lets the Bucket back down the Intake port will open again to allow the Oil in or Out as needed.. Thermal Expansion/Contraction. or Cam Wear.. When you have a 'Flat Bucket' either the Oil Can't get in to Fill the Gap. or the Intake port does not close quick enough.. and you have a Tick.. Generally it's a dirty oil thing that causes it.. Hyd Lifters can be a Problem, as at the Higher RPM's the Valve will Float, and the Pancake Cylinder will 'Pump Up' to fill the Gap it thinks it sees when the Lobe lets go of the Bucket, but the Valve is not yet on its seat.. Then you will get a Bad Missfire after a High Rev that will eventually go away after the Lifters leak down and the Engine Valve can actually sit back on it's seat and seal again... Sometimes it will take a LONG time.. I Floated the Valves on Dads 65 GTO doing a Burnout in the High School Parking Lot in the Early '70s.. Sounded like Krap as I limped it home thinking I killed it.. On the Drive home it did settle down.. Whew.. SOMETIMES if you Float the Valves on a Bucket and Shim, you can get the Shim to Come off the Top.. Things go down hill really fast after that.. Make sure the Bucket and Shim is VERY Clean underneath the Shim, and the Air Can't get under the Shim to Break the Suction to let the Shim Float Out.. Cj
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