Ariel Owners Motorcycle Club

When I first got my W/NG, I noticed a small oil leak around the lower banjo joint of the rocker oil feed pipe.
On closer inspection, I see that someone has stripped the thread in the gear cover where the oil feed stud goes. So, they have drilled it out and tapped it a larger size, and made a custom oil feed stud. It's a bit of a bodge (which is why it leaks). I could make a new oil feed stud but I am not convinced it will ever be oil tight.
Looking around I have a choice of at least 2 gear covers and I see that the club sell the correct oil feed stud, although they list 2 sizes (1/4" or 5/16").

I am really seeking some guidance here on whether I should cut my losses and replace the gear cover or persevere with making a new better fitting stud?

If the repair has not been done so that the stud is perpendicular to the case I doubt if it will ever seal. It is hard to find one of these cases in good condition as there are so many things that can go wrong with them and there are a 1001 variations. That stud is 1/4" from 1932-49 then 5/16.

The problem with that stud is that it is CEI 26tpi thread. The best repair is to tap the hole in the timing cover 5/16" whitworth and make a stepped stud to suit. My Red Hunter has run with this modification for upwards of 30 years.

That’s pretty much what a previous owner has done Paul, except the stepped stud is not quite right as it does not present a flush surface for the washer which sits next to the case. Also, the 1/4” part of the stud has a torn up thread.
So, I’ll get an engineer friend of mine to make a replacement.
Did you use any type of jointing paste in the thread/case or on either side of the base washer?

All I use is a fibre washer each side of the banjo. After running for a while, you need to re-tighten the nut, as for all fibre washers. Before re-fitting the oil pipe it is always worth annealing it (which probably involves re -soldering the fittings on afterwards) to prevent breakages. An annealed pipe will give no trouble for 10 years, in my experience.

paul.jameson wrote: ↑Sun Jan 22, 2023 8:32 pm An annealed pipe will give no trouble for 10 years, in my experience.

I imagine a copper fuel pipe would last less time between heat treatment Paul?

I don't know the answer to that, except to say that I haven't had problems with the copper fuel pipes on my Squares (when fitted) but I suspect the vibration regime is rather different between petrol tank and carb as opposed to between two points on the same engine. If in doubt, anneal after a certain mileage. If the pipe bends easily, there is no problem. If it is very rigid, it will fail before long.

An update. I have managed to buy a good condition gear cover (from a w/ng with the same casting number), and a friend has given me the correct stud. I am borrowing a magdyno pinion removal tool tomorrow. My plan is to remove the endless chain and 2 sprockets, then the 5 screws and gently remove the gear cover.
My question is, is it necessary to remove the magdyno first? and will I need to time the valve gear/magdyno on assembly (assuming nothing moves)?

You can leave the magdyno in place. Set the engine to tdc to remove the load on the camshaft.