[singleminded]

Right, just had fun turning a test bar to check the diagonal hole. The hole is to stop hydraulic locking of the tell tale.
I thought I had a set of micro frills but no.
So a Number 60 is much too big at around 1mm, I ended up with a 0.79mm test wire which is 1/32".
You are going to need a very fast speed and lots of lubricant and a lot of very small cuts withdrawing the drill to clear swarf to manage that without snapping the drill in the hole.
The subject of springs in the telltale is fun, it will depend on which spring you have in the rocker box elbow. I fitted a piece of throttle slide spring and trimmed it to get the pressure I was looking for also doing the same with the elbow spring( which was a cut down Vincent inner cush drive spring. i left the elbow out of the rockerbox cover but still connected to the pipe and ran the engine.without the elbow spring you will end up with a 4 foot jet of oil and low oil pressure.I played with the top spring pressure till i got a nice steady drip,about 1 a second to start with..If you don't fit the elbow spring and ball you will end up over oiling the top end and the oil will end up running down the head and barrel even with a Number 50 jet in the elbow.

[Ian Roberts]

Hi all
Thankyou for your useful comments on my previous posts.

The previous owner damaged (broke off) the threaded part of the timing cover holding the oil pipe union feeding the rocker box.
This has been aluminum welded and all necessary engineering work completed.
The diagonal oil way feeding the rocker box (which I did have the correct drill size put to one side) has now been put away by accident.

Could anyone confirm the drill size for the diagonal oil way through the timing cover to the main oil feed.

Has anyone any suggestions for the tell tale - sealing - spring etc.

Thanks

Regards Ian