Full set of 4 Dural alloy valve top caps and special thin lightweight collets set of 8, to fit BSA A50 and A65 all years, always check fitted valve spring height is no less than 1.37 inch ( 34.78mm) if using race valve springs, with valves at full lift, at least another 2mm lift should be possible of valve spring coil binding will occur and cause camshaft and follower wear and possibly pushrod failure.
