Non return valve

[not so speedy]

I am dismantling the gearbox on my way to splitting the crankcases and have come across, what looks to me, something not quite right.
I have taken the  inner gearbox cover off and whilst there checked the non return spring with ball bearing. Sure enough it was jammed with some silicone that the previous owner had spread on everything!
The other side of the case to the hole where the ball sits, I find a fibre washer. This somehow doesn't seem right, I cannot find a reference to this in my parts manual and I have seen a video where someone refers to an O ring there.
Can anyone help?

I have tried to attach a picture but failed miserably I'm afraid. I have resized the pic and selected it in the "Attach" box but then nada! 

Malcolm

[not so speedy]

Ooh there's the picture.

[Spaceman]

I think originally there was no seal between the inner timing cover and the crankcase holes for the NRV oil pathway but, in 1969, grooves were machined around the holes to take a 3/16 X 5/16 O-ring (69-0289). In this case, you haven't said what unit single this is and what year?

[not so speedy]

Sorry, it's a '68 B25 Starfire.

[Spaceman]

I believe originally, it would have been a plain hole for the NRV oil passageway and someone has machined an enlarged outer hole to take the fibre washer. It would be interesting to see a pic without the washer in place? The obvious problem with what they've done is that the web was not wide enough and the enlarged hole looks to be open at the side.

A fibre washer may not be the best way of sealing the joint in the oil passageway unless its thickness is just right. A thick enough O-ring might be better but I would definitely consider using JB Weld or similar to close the enlarged hole in order to provide the proper 360 deg enclosure of the O-ring.

[not so speedy]

Hopefully there will be a picture attached.
The fibre washer came out easier than I first thought and reveals that the gallery underneath hasn't broken through at the side.
Can I just put an O ring in place of the fibre washer? Or do I need to get a groove machined for that.
I understand early engines didn't have anything there but did they have the recess that the washer sits in?

New to BSA's so learning a lot!

Malcolm

[Spaceman]

The picture may be a bit misleading but it does look as though the gallery is more or less open at the lower side. I may be wrong but I think originally the cover had a plain hole and someone has machined the gallery - perhaps the person was worried by the lack of some sealing mechanism especially if the surfaces around the hole were a bit battered.

The later covers had a slot machined for the O-ring to prevent any possibly of the O-ring spreading out and partially covering the hole. However, I'm sure an O-ring would do the job provided it's OD is the same as the diameter of the gallery and you choose its thickness to ensure an adequate level of compression. Since there's no slot, it might be a good idea to use some grease to keep the O-ring in place when you re-assemble the engine.