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Camshaft availability.

Brampton Bryan

New Website User
Non-VOC Member
Can anybody tell me what options are open to us.
I have tried our trusted friends at VOCSpares at Lymm only to be told that there have been none available for the last two years and no signs for the future.I asked if there was a drawing available to check timing mark orientation(answer was no),it seems that cams have moved relative to the pinnion on many occasions is this a design weakness ?
Have the club just built a complete new machine from new parts but with reclaimed cams in then?? Garry Robinson reclaims cams using Stellite 12 and stellite 6 for the followers with great results and welds them to avoid movement if the interferrence is insufficient.He also makes new camshafts. How many other options are available to us. Can anyone help.
Thanks, Bryan.
 

derek

Well Known and Active Website User
VOC Member
cam availability

I have also just tried to obtain cams, and eventually sent some to Gary Robinson for reclaiming, as I also want a new cam wheel, he stated that they were best obtained from Maughans (which he would do on my behalf) with the correct ground fit too suit the shaft, he would inform Maughans of the size. Seems good to me.
The spares Co., have had the cam blanks at a firm for grinding for, as you state , a couple of years. I do not see why they can not use Maughan or Gary Robinson.
 

Vic Youel

Well Known and Active Website User
Non-VOC Member
Cam Drawings

I also wonder whether the drawings project has made drawings available for the various cams.....does anyone know? Have cams been manufactured in accordance with these drawings to test them?

Further......what drawings/designs do Gary Robinson and Maughan's use.

What is the origin/design of the cams which the club shadow utilises?

Lot's of questions here. Would make interesting reading if an MPH article to update previously published information was composed by someone "in the know."

Cheers

Vic
 

Tom Gaynor

Well Known and Active Website User
VOC Member
Cam designs

PEI explains where his cam designs came from in FYO (and in his autobiography). There wasn't a lot of science involved, largely because he found he had to produce cam masters at his leisure, so long as they were ready in about 30 minutes. Gary Robinson 105 cams have some connection with Ian Hamilton that I can't remember. Ian designed them? Modified another design? Commissioned them? Doubtless there are details in Ian's MPH articles. What I remember Gary saying is that they are basically Mark II's with less overlap, and that many users think there's less spitting back as a result. I can't say I'd noticed, which isn't to say it isn't true.
From observation, Vin cams are look mild, similar to Rudge Special cams ("Special" means "Very Ordinary" in this context). Rudge Replica cams, which I use (in a Rudge Ulster), are two near-parallel flanks with a base circle at each end - like the classic description of a Manx Norton cam: a housebrick rotated off-centre. They (Replica cams) work very well. I half-expected a buzzy engine, but in fact it pulls like a train from zero revs to god knows what. CR is about 7:1. I suppose that having two small valves to shift rather than one big one gives more opportunity for aggressive valve acceleration rates.

Stepping back a bit, a Rapide produces 45 bhp, 22 1/2 bhp per pot. That isn't exactly radical. As noted elsewhere, the legendary Guzzi 500 cc plonker, the Gambalunga, named for its long stroke, originally had dimensions of 84 x 90. I'm not complaining: a big, softly tuned motor makes for a very pleasant bicycle at, say, 60 to 90 mph. I'd hate to lose that in pursuit of performance I'd never use.
 

bmetcalf

Well Known and Active Website User
VOC Member
Cam Design

Supposedly, the Emmerich/Andrews/Megacycle cams are "constant acceleration" design. Of course the acceleration has to change from positive to negative when the follower is between the base circle and the nose. This makes me think the term was more of a marketing term than an engineering concept.

I was a poor student, so I find it difficult to think of a way to describe the varying contact point of the cam and the follower that makes the valve motion more complex than a roller lifter in a US V-8. You could do it graphically every few degrees to try to optimize things, but the ideal motion might be impossible with the mass of the valve and the available springs.
 

Len Matthews

Well Known and Active Website User
VOC Member
Brampton Bryan raises an interesting point; if the Club/VOCSCo Black Shadow was supposedly built from all new parts, how come they have had no cams in stock for two years? What's more, I loaned an RFM to assist the Drawings Project-it has not been returned. How many others have contributed parts and /or drawings are still waiting?
 

BlackLightning998

Well Known and Active Website User
VOC Member
Isn't there a Club Officer in charge of the Drawings Project who could comment?

Vic and Len seem to be asking a similar question - isn't there someone in charge of the Drawings Project for the VOC who could provide a response?

Stuart



Brampton Bryan raises an interesting point; if the Club/VOCSCo Black Shadow was supposedly built from all new parts, how come they have had no cams in stock for two years? What's more, I loaned an RFM to assist the Drawings Project-it has not been returned. How many others have contributed parts and /or drawings are still waiting?
 

Graham Smith

Well Known and Active Website User
VOC Member
VOC Forum Administrator
VOC Forum Moderator
The correct way to contact Club Officials…

Yes, there is a Club Official who is in charge of the Drawings Project. That person is of course Arthur Farrow, the Club's Drawings Manager.

However, most elected and appointed Officials of the VOC don't monitor this forum 24 hours a day, 7 days a week (unlike many companies who have the luxury of a number of paid staff who monitor this sort of website, and can answer such questions), all VOC Officials are unpaid volunteers who have huge demands on their time (like most other people these days).

This forum, isn't the place to ask official type questions about such things. The correct way of asking such a question would be to write a 'conventional' letter to Arthur Farrow (not a two line e-mail). The address for all VOC officials is printed on the inside front cover of MPH

Now, I'm not suggesting this is the case in this instance, but the problem with the internet, e-mail and this forum, is that it's far too easy for someone to write a 30 second, two line e-mail to a Club official, demanding the answer to a question that will potentially take that particular Club Official hours and hours of work to answer. Because of this, I know at least one Club Official who refuses to answer questions of this type that are received via e-mail.

I hope this helps.
 
Last edited by a moderator:

Graham Smith

Well Known and Active Website User
VOC Member
VOC Forum Administrator
VOC Forum Moderator
I spoke (via an old fashioned telephone conversation) to Arthur Farrow earlier on, and he informed me of the following:

Mk 1s - These are not currently available through the VOC Spares Company Ltd., but they placed an order some time ago, and are still waiting for an anticipated delivery date (don't hold your breath).

Mk 2s - Gary Robinson (who advertises in MPH) sells these BRAND NEW.

MK 3s - Patrick Godet has a limited supply of these, but they are very expensive, and Patrick doesn't normally sell spare parts to 'Joe Public'.

This unfortunately is all I am able to tell you.

Should anyone have any further questions about anticipated delivery date for the Mk 1 cams, then I suggest David Meadowcroft at the VOC Spares Company Ltd. is the person to speak to.
 

BlackLightning998

Well Known and Active Website User
VOC Member
Len - It appears Arthur Farrow is the man to enquire of for your RFM?

Len,
I deduce from Graham's posting that it would suggest that Arthur Farrow is your man to enquire of by letter to identify the whereabouts of your RFM.
Cheers
Stuart

Yes, there is a Club Official who is in charge of the Drawings Project. That person is of course Arthur Farrow, the Club's Drawings Manager.

However, most elected and appointed Officials of the VOC don't monitor this forum 24 hours a day, 7 days a week (unlike many companies who have the luxury of a number of paid staff who monitor this sort of website, and can answer such questions), all VOC Officials are unpaid volunteers who have huge demands on their time (like most other people these days).

This forum, isn't the place to ask official type questions about such things. The correct way of asking such a question would be to write a 'conventional' letter to Arthur Farrow (not a two line e-mail). The address for all VOC officials is printed on the inside front cover of MPH

Now, I'm not suggesting this is the case in this instance, but the problem with the internet, e-mail and this forum, is that it's far too easy for someone to write a 30 second, two line e-mail to a Club official, demanding the answer to a question that will potentially take that particular Club Official hours and hours of work to answer. Because of this, I know at least one Club Official who refuses to answer questions of this type that are received via e-mail.

I hope this helps.
 

Vic Youel

Well Known and Active Website User
Non-VOC Member
Drawings project

Graham,

Did the Drawings Manager give any information on the status of cam drawings and will the VOCSC cams (when they are availble) be made in accordance with club drawings?

Also did he know which cams, and from what source, the club shadow uses?

As you know I am very interested in the findings and flow of information to members from the drawings project.

Vic
 

Graham Smith

Well Known and Active Website User
VOC Member
VOC Forum Administrator
VOC Forum Moderator
Hi Vic

No, I didn't go into any great detail with Arthur about Cams, as it was quite a short conversation while he was on his mobile walking round the auto-jumble at Kempton. The reason I spoke with him, was so I could put some sort of a reply on here, albeit basic.

I'm sure if you speak to Arthur (phone number on the inside of MPH), he'll give you all the information you require.
 

Tom Gaynor

Well Known and Active Website User
VOC Member
Cam design

This time I checked the book instead of relying on my recollection......

PEI explains in his autobiography how he "designed" the cams (pages 345-6 and 374).
The cams for the B Shadow were blue-printed Rapide cams, similar but not identical to the pre-war Comet. The Comet cams were modified by PEI (in the light of the series B's different follower geometry) to get the same valve timing.
"Meantime", PCV had undertaken to prepare a Shadow for John Edgar for a record attempt at Bonneville in September 1948. It was now May 1948. The bike would have to be shipped in August.
PEI thought it would need a bit more oomph, and "hotter" cams were an obvious step. The cam master was made by PEI himself by cutting a narrow slot in a set of Shadow cams, soldering a piece of steel plate into the slot, and modifying that until he got the figures (timing, overlap, lift) he thought were going to be needed to break the existing record (136 mph). He was helped by an apprentice, one John Surtees. I wonder whatever happened to him?
Executive summary: PEI made a master to produce the timing he thought was needed, hardened and ground several sets of cams from the master, checked the timing of those, made a large scale template from the new cams, then made a drawing from the template. Those were obviously "Mark II", so the earlier ones must be "Mark I": history written backwards, as is most history.
That raises the intriguing possibility that since the drawing could only be an approximation to the cam profile, limited as drawings were then to circular arcs and straight lines, then "new", "official VOC" Mark II cams, made to a drawing, wouldn't be the same as cams made from the master. Oh, dear. Arthur'll be bending that mobile 'phone again.......
 
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