Author Topic: B31 Cams  (Read 5238 times)

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Offline Clive

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B31 Cams
« on: 01 Oct 2005 at 20:32 »
Hi Everybody,
Has anybody tried a repair scheme to rebuild the teeth on the camgear ?
Thanks
Clive

Offline Doug

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Re: B31 Cams
« Reply #1 on: 02 Oct 2005 at 05:46 »
Clive,

Most folk just replace it with another used camwheel, they are about.  I think any cams from a 250 or 350cc engine from 1931-1936 will fit. 

I do not know if you have spotted the joint yet, but Douglas made the camwheels from two separate pieces.  There is the gear itself, and then the cam lobe which goes right through the gear and sticks out both sides.  The gear has a cam shaped hole broached in it to suit (patented.)  Once pressed in, the cam got a light lick on the grinder to clean and true it up.  So conceivably you could machine a new gear and press off the old and press on the new.  The main problem would be cutting the cam shaped hole in the gear, and that comes down to what kind of machinery you have or have access to.  Also pressing the cam into the new wheel would require some care, actually I would shrink it on.  This would allow you to set up some precision shims so that you just drop the hot gear over the cold cam and everything rests at the correct height and orientation while the gear cools.  I assembled a pair of Douglas gears and cams this way for a 1928 600sv (same valve mechanism design as the B31), but in my case made both the gear and cam new as they were missing entirely.  To simplify things, I made the center section of the cam a cylinder a diameter big enough to clear the lobe of the cam.  That way I did not have to make a cam shaped hole, I just bored a round hole through the gear.  Of course no sooner than I had done this and a good used set of cams turned up. 

-Doug

Offline Clive

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Re: B31 Cams
« Reply #2 on: 02 Oct 2005 at 23:04 »
Thanks Doug,
I have disassembled cams before swapping the best gears and cams on my EW, but I don't have spare gears or cams for the B31 . What a great idea the circular hole in the gear and new cam . All sorts of possibilities spring to mind . I personally don't have the machinery to do the job but I do know someone that has . Still hoping though that someone might have a set of spares which would save the expensive exercise.

Once again thank you very much for the prompt reply.
Regards
Clive Hallam    LDMC No2896 


« Last Edit: 03 Oct 2005 at 13:44 by alwyn »

Offline Stuart Lister

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Re: B31 Cams
« Reply #3 on: 03 Oct 2005 at 07:33 »
Hi Clive,
I have a pair of good used cams if you're interested. Where in the world are you?
Stuart

Offline Clive

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Re: B31 Cams
« Reply #4 on: 05 Oct 2005 at 01:44 »
Hi Clive,
I have a pair of good used cams if you're interested. Where in the world are you?
Stuart
Hi Stuart,
As far away as i can get!! lived in UK 26yrs ago now its North Island New Zealand .
I am Very interested in your offer, please let me know the cost of said cams and postage so i can forward the monies to you .
You may contact me via the email or Personal Message links on the left. 
Thanks for the offer hope this meets with your approval.
Regards Clive Hallam   
« Last Edit: 06 Oct 2005 at 02:59 by Dave »