[phutton]

In theory, there should be little load on the key, as the taper is generally considered to have sufficient "grip", and the key is just for location. It might be worth lapping the rocker to the shaft, especially if there has been damage to the taper surfaces.

P.

[singleminded]

I was supprised on the spare rocker I have at how shallow the keyways were for the force that's exerted on them..John

[Steve_M90]

John, you are spot on - both keys sheared. I followed your instructions but I didn't have to tap the spindle too hard to get it to release. I've got one of the damaged keys out, just working on the other. New key material being supplied by Tony P.

[singleminded]

The only thing that I can think of is that the 2 keys at the removable end of the rocker have sheared..the rocker arm at the nut end is fitted on a tapered and keyed shaft..if you slacken the nut so that it is flush with the end of the thread and the using a soft drift( copper or soft brass, maybe aluminium) with the rocker box supported tap the rocker shaft in against the casting to release the taper..You need to be careful as finding another rocker box will be almost impossible..John

[Steve_M90]

On the exhaust valve, the tappet pin cannot be adjusted to be close to the valve stem. On disassembling the rocker box it is clear that one of the arms has moved on the shaft. The photographs show the arm in both extreme positions - you can see the angles are different between inlet and exhaust. The "input" end has a nut on it. The spares book implies there is a key in this end. The "output" end, the arm seems to be held in place by a screw. Nothing seems to be loose.

Has anyone taken the arms off the shaft? Should I be able to undo either the nut or the screw? Clearly one of them needs to be removed to remove the shaft from the box.

Advice welcome.

Steve