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At the rear base of the cylinders of the A10 there is a vertical screw pointed downward toward the lifters. According to the BSA parts catalog it has a ball beneath it, and a horizontal peg.

The part numbers are
11167-0331 peg
40101-4676 ball
10167-0276 or 10267-0949 screw

What are these parts and what do they do? And does it matter if the ball is missing?

My engine is all back together and I remember nothing of the ball or peg. And the last time I rebuilt an A10 was decades ago.

It holds the cam follower retaining pin in place
Good, makes sense. What happens if the retaining pin is left out? Is there anywhere for the cam followers to go? I just don't want to tear it back down.
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