CA77 Cam Lift Specification?That doesn't look right. 4.56mm = 0.179" 5.69mm = 0.224" That .118 number is a mistake in the original specs. Some poor little tech writer converted the mm to inches and got it wrong. There's a couple of those typos in the manual. It's almost exactly half the correct answer. Sticky slide rule I guess. I have just taken some measurements from an early (1960) C72 Dream engine.
Number C72E-029951 Inlet 31.36 max 26.19 base = 5.17 Exhaust 31.42 max 26.15 base = 5.27 The cam looks a little worn but those numbers are pretty much the same. This cam is the one with the big 'square' governor on the sprocket. G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
Well the book specs calls it Cam Lift: "Cam lift INTAKE 5.69 mm (.222) EXHAUST 4.56 mm (.178”)" As I said in one of my earlier postings here, I put a dial indicator on the cam and zeroed it when it was at the minimum and rotated it to the highest point and took the reading. "All 4 cam lobes have the same Lift (5.69mm 0.222") which also was seen when I measured all 4 lobes what I take is call Cam Bearing Height (as if you were measuring the cam diameter at the widest point) at 31.46mm 1.246" Point being, all 4 lobes are the same height.... Not what the spec calls for. So maybe the one you found was not "a manufacturing error", but a CA cam? Looking at it from another perspective, -if- my exhaust cams being 5.69mm vs the specified 4.56mm is a manufacture error and knowing that there is no interference with the piston, how would that effect the running? It seems to run fine, but on the other hand I do not have anything to compare it to. Still a Mystery. George An earlier cam. Now that's a possibility I hadn't considered. I never had one so I can't comment. It's possible I guess.
What would it do to performance? I suspect not much. More exhaust lift might mean better exhaust gas flow and better performance if that was the limiting factor. on a street motor I wouldn't expect it to make much difference. A more interesting question is why did they reduce the exhaust lift for the higher performance CB72?
My guess is that the original (C72) cams were identical profiles making manufacturing easier, then the CB72 came along and they needed to find some clearance because of higher revs and shallower combustion chamber. The answer - shave a bit off the exhaust cam?? It will be interesting to look at the profiles to see if there are major differences between the two. When stripping this old head I noticed that the rockers were slightly different too. The cam follower pads were in very good condition and have lube holes on the rubbing face. G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F This gets curiouser and curiouser.
AFAIK the rockers with holes in the pads for oil feed are the last ones made - the latest design iteration. Earlier ones had a hole to spray oil from the pivot boss onto the cam. G-man Does it look like that motor has been apart or does it look like all original parts? Sounds like teh cam and rockers may have been replaced and they kept the sprocket carrier /advancer Teazer
It's possible but the engine was last in use in 1968. Pistons are on standard bore but the motor was in pieces and very rusty due to bad storage when i got it last year. Very difficult to know what the history is after 40-odd years....... I just bought it because it was an early one. I'll get some pictures in a couple of weeks. I'm away on business for the next week or so. G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
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