The Spares Company
Club Shop/Regalia
Parent Website
Contact Officials
Machine Registrar
Club Secretary
Membership Secretaries
MPH Editor and Forum Administrator.
Section Newsletters
Technical Databases
Photos
Home
What's new
Latest activity
Forums
New posts
What's new
New posts
Latest activity
Information
Bike Modifications
Machine Data Services
Manufacturers Manuals
Spare Parts Listings
Technical Diagrams
Whitakerpedia (Vincent Wiki)
The Club
MPH Material Archive
Flogger's Corner
Obituaries
VOC Sections
Local Sections
Local Section Newsletters
Miscellaneous
Club Assets
Club History
Club Rules
Machine Data Services
Meeting Documents
Miscellaneous
Essential Reading
Magazine/Newspaper Articles/Letters
Adverts and Sales Brochures
The Mighty Garage Videos
Bikes For Sale (Spares Company)
Log in
Register
What's new
New posts
Menu
Log in
Register
Install the app
Install
Home
Forums
Forums: Public Access
Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Camshaft availability.
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="Tom Gaynor" data-source="post: 4084" data-attributes="member: 4034"><p><strong>Cam design</strong></p><p></p><p>This time I checked the book instead of relying on my recollection......</p><p></p><p>PEI explains in his autobiography how he "designed" the cams (pages 345-6 and 374). </p><p>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. </p><p>"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. </p><p>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? </p><p>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. </p><p>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.......</p></blockquote><p></p>
[QUOTE="Tom Gaynor, post: 4084, member: 4034"] [b]Cam design[/b] 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....... [/QUOTE]
Insert quotes…
Verification
What was Mr Vincent's Christian Name?
Post reply
Home
Forums
Forums: Public Access
Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Camshaft availability.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
Accept
Learn more…
Top