How to loosen the camshatf nut?

laurentdom · Mar 17, 2014

Hi All,

Do you know the size of the camshaft nut (seems to be somethnig like 25,5 millimeters, i.e. larger than 1 inch) and how to prevent the engine from rotating when undoing it?

Many thanks and regards

Laurent

Keith1069 · Mar 17, 2014

Should be 1" AF. 26mm might be OK but I would shim it to make sure it is not a loose fit. If the primary is all connected and the rear chain put it in 4th gear and hold the brake on or adjust the brake to lock the drum (assuming not a Mk3). If the primary is disassembled then carefully block the timing gears with some hardwood or similar material, hard plastic, nylon etc.

toppy · Mar 17, 2014

I believe that the nut is whittworth (well mine was) but sometimes depending on the quality or condition of your tools (or my tool to) other sizes my fit. So just use best fitting one or look on net for size equivalent an treat yourself to new tool.
You should remove barrel an pistons then put bar through little ends. You should use cutaway old timing cover or Andover Norton now sell a cheap tool. To prevent damage to the half time spindle.
I wouldn't lock the gears (like on triumph) or the rods without supporti the half time spindle.
Why are you removing the nut an how far apart is rest of engine?????
My cam was worn out so I was not wurried about damaging it so with barrels an pistons off I could hold the cam with stillsons to undo the over tight nut the PO had used hammer an chisel on.

pete.v · Mar 17, 2014

I guess it is safe to assume that the head is on and you are changing the cam chain of cam timing sot of this. If the head was off, there is a hole in the crank to put a rod to stop rotation.

An impact wrench is a very useful tool on these bikes and is worth the expense. Although it takes a good air compressor to run a pneumatic, an electric impact is awesome. I have a Dewalt 18v. It is as good as the Milwaukee plug in.

Edit: I meant to say the top end to expose the crank and not just the head. Thanks JimC.

JimC · Mar 17, 2014

If the head was off, there is a hole in the crank to put a rod to stop rotation.

How is the crankshaft exposed with only the head off?

pete.v · Mar 17, 2014

JimC said:
If the head was off, there is a hole in the crank to put a rod to stop rotation.

Click to expand...

How is the crankshaft exposed with only the head off?[/quote
Yes, I mean the top end.

thanks Jim what would we do without you. god help us if we're left to discern on our own.

dynodave · Mar 17, 2014

laurentdom said:
Hi All,

Do you know the size of the camshaft nut (seems to be somethnig like 25,5 millimeters, i.e. larger than 1 inch) and how to prevent the engine from rotating when undoing it?

Many thanks and regards

Laurent

camshaft nut is 5/8BS-9/16W
bonus:
crankshaft nut cw to loosen(LH threads) 9/16BS-1/2W
you can buy whitworth tools at almost any "real" norton supplier in north america
snap-on, Kokon, elora, craftsman (fleamarket/obsolete), proto, dowidat, gordon, britool are all in my pile

not sure you can in England though

JimC · Mar 17, 2014

pete.v said:
JimC said:

If the head was off, there is a hole in the crank to put a rod to stop rotation.

Click to expand...

Click to expand...

How is the crankshaft exposed with only the head off?[/quote
Yes, I mean the top end.

thanks Jim what would we do without you. god help us if we're left to discern on our own.

I know we could do a lot better without you.

pete.v · Mar 17, 2014

JimC said:
I know we could do a lot better without you.

I'm glad you didn't say "I know we could do a "whole" lot better without you." I might have been hurt then.

"If you want to see the true measure of a man, watch how he treats his inferiors, not his equals."
"To measure the man, measure his heart."

pete.v · Mar 17, 2014

laurentdom said:
Hi All,

Do you know the size of the camshaft nut (seems to be somethnig like 25,5 millimeters, i.e. larger than 1 inch) and how to prevent the engine from rotating when undoing it?

Many thanks and regards

Laurent

Laurent, I cannot recall whether I used an 1 1/16 or a 1 1/8 but i do know that i use a 6 point socket which caused no ill effect to the nut or the socket.

laurentdom · Mar 17, 2014

Many thanks to you all.

Yes Pete, I need to replace my timing chain whilst keeping the engine in place and un-dismantled (at least voluntarily

)

I'll try & find the appropriate socket (to be verified, but should be 1" 1/16) and will use an "Andover-like" device to keep the intermediate gear in place when loosening the nut

toppy · Mar 18, 2014

It sounds then like you still have the primary drive all in place so the advice on using rear brake an fourth gear should work to lock the engine (with someone to help) putting peice of wood between rear sprocket an drive chain should also work if you have no help but the cam nut should not be overly tight.

Matt Spencer · Mar 18, 2014

When you consider the cutaway timing cover trick is to support the idler shaft while turning the motor by the cam nut :shock: :? :x hopefully with the plugs out ,
UNDOING the nut without the cut away cover is seriously likely to do something unpleasant about the idler shaft .

A funny tool with inverse ? sprocket teeth , to fit between the two cam chain sprockets is really the go . and available from Norton suppliers ? ? ? .

Other aspect of undoing against the chain is the likelyhood of stretching the eeny weeny chain , across a few of the links . Ensureing uneven tension
and strain in operation . removeing the chain BEFORE undoing the NUT would be sensable , before getting the assistant to stick his finger in to jam the sprocket :shock:

:lol:

Towner · Mar 19, 2014

By the way, AN offers a support tool for the intermediate shaft since last month:

http://www.andover-norton.co.uk/News.htm

http://www.andover-norton.co.uk/images/06.7325_600.jpg

http://www.nortonmotors.de/ANIL/Norton% ... art=067325

It is not that cheap, but cheaper than cutting a timing cover.

DogT · Mar 19, 2014

I got a burned up timing cover for $20. Took me a while to drill enough holes in it though. I feel kind of bad, it could have been rescued.

How to loosen the camshatf nut?

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