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Cam Followers

Puddle jumper

Well Known and Active Website User
Non-VOC Member
Hi guys,
Does any one know if roller cam followers have ever been made for a Rapide. it seems that if the engine has a weak spot, it is cam and follower wear, so I was thinking of making a set to see if this helps solve the problem.
 

timetraveller

Well Known and Active Website User
VOC Member
Oh Dear!! Even ignoring the lack of space; the Vincent cam is designed to work with a FLAT follower. Using a radius will dramatically alter the timing and the velocity and acceleration curves. Also, when designing some polynomial cams I bothered to do the calculations as to where, when and for how long a curved base follower touched the cam. It is a nightmare with the contact point on the follower or roller rapidly moving from almost one side of the follower to the other and back again. Rumour has it that there is at least one engine running with roller followers but from my calculations, which could be wrong, it would be a waste of time.
 

TouringComet

Well Known and Active Website User
VOC Member
VOC Forum Administrator
VOC Forum Moderator
Clem Johnson's 'Barn Job' drag bike had roller followers, and I'd imagine different cams to suit. Mike Parti obtained a set of crankcases discarded by Clem, already modified for roller followers, and built it up into a complete motor, retaining the roller followers.
 

clevtrev

Well Known and Active Website User
VOC Member
Clem Johnson's 'Barn Job' drag bike had roller followers, and I'd imagine different cams to suit. Mike Parti obtained a set of crankcases discarded by Clem, already modified for roller followers, and built it up into a complete motor, retaining the roller followers.
I`ve a picture of those cams somewhere, imagine a square with one curved side.
 

Bill Thomas

Well Known and Active Website User
VOC Member
Hello Puddle Jumper,
I don't think you will wear out Gary Robinsons Cams and Followers, !
But what about Somerton type Cams.
I don't know if anybody around the world could make them ?.
This is the place to find out !!.
They are square type cams with large curved followers, When you turn the engine over there is much less clacking from the valve gear.
I have never seen or used Mk III s only Mk II s.
I have used them in my Special since 1980 and I love them !.
The bike feels the same as when on MkII s .
I don't know if Timetraveller has done one of his tests on them but I can't see why Nobody has made them, For a start the follower is very thick at
the point where I broke a standard one a few years ago on my other bike.
All the best Bill.
 

timetraveller

Well Known and Active Website User
VOC Member
Yes, I have checked out Somerton cams and followers and in fact used them in my sprinter many years ago. I bought them off Tom Somerton himself and was under the impression that they were Picador cams until I read something in MPH several years ago, by I think the Prof. If he has it correct, and I understood it correctly, then Tom made a very quick copy of a Picador cam but used the wrong radiused follower for speed. This might have lead to some errors but the bike went very well; 135 at the end of a standing start half mile at Long Marston. I did not get any followers from Tom and in fact ground my own by hand after having some stellite welded on. I used a correctly radiused pair of steel disks clamped to each side of the welded up follower to guide me. When I came to design my new cams I tried to use a genuine Picador follower shape but they will not work with valve lifters so designed a hybrid between a standard follower and a Picador one. I did all this a few years back and took the bike apart to fit them and then have been sidetracked with other projects so have not got round to trying them out in my bike. I am loathe to sell any to anyone else until I have tried them out in my own bike but time is passing and I am still not free of some of the work I took on years ago, hence the delay. Getting them made is not the problem but one needs cams, followers and shorter push rods together to do the job. If you look in MPH several years ago you will see the lift, velocity and acceleration curves of my new cams compared with standard one or I could paste the diagrams into this Forum if wished.

Perhaps this autumn!!
 
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