why would anyone not run hyd. Lifters instead of solids?
Simple. Because one has to. The original Stovebolt engines have no provision for oiling in the lifter bores. It is isn't until the later Power Glide designs that an oil passage is created to feed a hydraulic lifter:
The solid lifter in a Stovebolt runs on residual oil collecting in the floor of the push rod bay. The cam lobes run on spray from the crank case and weeping from the exposed side-holes in the lifters while riding on the base circle of the cam. In this regard the 'milk bottle' style lifter would be more accurately described as an oil bottle.
Solids where replaced by hydraulics because they are noisy and require adjustment. In spite of the fact that solids provide much more consistent (lash tunable) valve events.
regards,
stock49
