Brian
John Shanks was known as the King of Mt Druit during the mid 50s as he was almost unbeatable on his Ariel at that track during that period. John used either Vic Lyons cams (or later factory HS cams). During the 70’s Vic Lyons ran a Yamaha dealership in Lidcome. He ground a cam for me at that time. I subsequently broke a cam follower foot and did some cam damage and the cam was reground to hopefully Lyons specs by Claude Cartledge. The Lyons cam has a retarded valve timing and performs better if advanced one tooth to a near straight up timing. Vic Lyons passed away possibly 10 years ago and was living in the Batemans Bay area at the time. A lot of Lyons equipment ended up with Stan Corish’s widow who sold it off. The cam master blank is possibly in Nowra with the wife of another deceased Ariel owner.
The holes that you are referring to may be the balance holes in the gear wheel that were standard on all later single lobe cams.
To my knowledge Senior generally only provided one cam grind to the public, so the cam you have should be the same as mine. The Senior cam that I have is almost a straight up valve timing (2 degree advance) and is a very good performer on unleaded. Years ago I spoke to someone who had a collection of 7 or 8 Senior cams that went from mild to wild. They had been a present from Senior to a very close friend.
Many Senior cams have a map of Australia on the outer cam face with Senior inscribed within the map, but not all Senior cams (including mine) have that. Does your Senior cam have the map.
Through bolting means the head bolts go through to the crankcase where they engage into an offset crankcase stud/nut, as in the attached photo. That way there is no tension on the base flange by the engine on compression stroke, however the disadvantage is the differential expansion of the alloy head and cylinder to a steel bolt to contend with which can result in pulled crankcase threads. I have used studs that have reduced shanks to make them a bit more stretchy.
I have created valve lift tables for Senior, Cartledge, Lyons and Corish cams. Measured at .050 lift the cams should give the following valve timing
Senior 35 57 64 31 overlap 66, LSA 103.73
Lyons 10 63 42 34 or if advanced one tooth 24 49 56 20 overlap 44, LSA105.25
Corish 23 55 64 14 overlap 37 LSA110.5
Cartledge advanced one tooth 21 62 63 34 overlap 55 LSA 107.5
Standard VH twin lobe cam 2 49 51 2 overlap 4 LSA 114
David
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