I am stripping and rebuilding a model 30. I have found scored big ends and a horridly scored piston (rear edge of right side piston) so i'm thinking that it has been run with the oil feed tap closed, but it's a new bike to me and i dont know much of its history. Main bearings seem OK. Maybe experienced members will have a view on this. While I plan rebuilding the engine (rebore, pistons, shells etc), I am noting the profile of the cams. I am used to "egg shaped" cam profiles but on this bike there is a distinct flattening on one side of the "egg" running up to the highest point on both cams. Does anyone know if this is correct, worn, important or not?? They are not scored, just an odd shape.
JAMPOT spares shop do not have any new stock of cams so I need to take a view as to whether the unexpected profile is an issue or not for me.
Thanks in advance for any advice.
Sorry, but I can't work out how to show an image ! - I think i need some sort of web platform to put it on and i'm not a teenager so its too much for me !
Cam profile OK or not ?
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DerekAJS30
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SPRIDDLER
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Re: Cam profile OK or not ?
Have a look at this post which may help.............DerekAJS30 wrote: ↑Wed Nov 01, 2023 10:43 am
Sorry, but I can't work out how to show an image ! - I think i need some sort of web platform to put it on and i'm not a teenager so its too much for me !
viewtopic.php?f=19&t=27956&p=237049#p237049
'There is a tide in the affairs of men
Which taken at the flood............'
Which taken at the flood............'
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Groily
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Re: Cam profile OK or not ?
https://britcycle.com.au/product/nos-aj ... amshaft-3/
If you look at the one here, and hover over it with the mouse, you'll see the look. I think yours sounds normal, with the flat(tish) profile one side.
If you look at the one here, and hover over it with the mouse, you'll see the look. I think yours sounds normal, with the flat(tish) profile one side.
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robcurrie
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Re: Cam profile OK or not ?
There is a section drawing of a twin engine in Christian's archive see here: http://archives.jampot.dk/technical/Cut ... e_1955.pdf
You will notice that the exhaust cam has a relatively flat side.
Also see page 52 of F W Neill's book on AJS Twins:
http://archives.jampot.dk/book/Workshop ... .NEILL.pdf
Rob C
You will notice that the exhaust cam has a relatively flat side.
Also see page 52 of F W Neill's book on AJS Twins:
http://archives.jampot.dk/book/Workshop ... .NEILL.pdf
Rob C
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DerekAJS30
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Re: Cam profile OK or not ?
Thanks everyone. Special thanks to Rob for the two links, they clearly indicate that the profile it slightly flat sided and my cams therefore look OK. That has saved me a lot of money and concern. Good job chaps !