We discovered what the root cause of the problem was.
The block had incorrectly installed lifter bushings, which resulted in a couple of lifters having no rotation.
But, to answer your question, that was a UD cam from before they closed.
Several years later on one of the mild circle track SBC builds, one cam lobe went flat on break in.
Pulled the cam, 15 were perfect, one was junk.
Slid in another cam, checked for rotation...... all were fine except that one hole. Zero rotation.
Ordered a cam with an extra .001 taper.
Even with that (.003 taper) there was barely any rotation.
That’s back when Schubek was still around.
Put one Schubek in that hole....... no problems.
Those don’t need any rotation.
