Originally Posted by Pre '68 Dave
A hydraulic lifter does not need oil pressure to work properly, it only needs to be full of oil.

True enough, but all hydraulic lifters have a slight, but continuous leakdown whenever the valve spring pressure is applied to them. The engine oil pressure must be sufficient to refill the lifter every time the spring pressure is released. (lifter on the base circle, with no lift of the valve) At very low oil pressure the lifter does not refill, so it eventually bottoms out and starts to rattle. A splash-oiler 235 with hydraulics would need slightly diferent valving to assure the lifters stay filled with the lower oil pressure available.

My comment about solid lifter cams being obsolete was simply to mention that newer, more user-friendly technology is available. For normal operation, hydraulic lifters just result in a quieter-running engine that does not need the periodic valve adjustments that solid lifter engines do. If I can fit an appropriate-grind hydraulic cam to any engine I'm building, it's my first choice. Until I get into the 7,000 RPM+ operating range, a hydraulic cam is also my go-to system for the race engines I build.
Jerry

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