| Also known as | 24-563 |
| Diagram | Fig. 2 — CYLINDER AND CRANKSHAFT · ref 10 |
| Subsystem | engine top |
| Listed in parts books | 1969–1972 |
BSA Nut, rocker adjusting screw (5/16" British Standard Cycle)
A 5/16 inch BSC locknut used on the rocker adjusting screw to hold valve clearance settings in place.
This is the locknut that holds a rocker adjusting screw in place once the valve clearance is set. It's a 5/16 inch British Standard Cycle thread nut, small hardware but important - if it backs off, the adjuster can walk and the clearance goes out, which changes how the engine runs and can get noisy at the valve gear.
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In the catalog it shows up across cylinder head and rocker figures as well as a few unrelated listings for timing cover and swinging arm areas, which is just how the parts book groups small fasteners rather than a sign this nut does double duty elsewhere. The catalog appearances span 1969 to 1972. It's also listed under the older number 24-563, same part.
If you're doing a valve clearance check or rebuilding the rocker boxes, it's worth having a few of these on hand since they're easy to drop or strip when you're working the adjuster back and forth.
We've never carried this one. Tell us what you're after and we'll go looking — you'll get a price and photos before you commit to anything.
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