AJS & Matchless Owners Club

I wold appreciate some information concerning the last version of the twin oil pump which has the relief valve in the base plate. The pump I have was refurbished by Ray Spencer and
the setting of the relief valve was noted on the baseplate as 95 psi. I recently checked the oil pressure and it was around 200 psi at tickover on startup with cold 20w/50 oil. I
took the pump off and removed the delivery pump to check the oil passages. I have attached a photo of the section of the base plate where the delivery pump is mounted (one) and a photo
of the base plate from the back with the internal oil passages indicated (two).

I was searching for the connection between the discharge port in the baseplate and the relief valve via the horizontal passage (in red), but all I have found is a very small hole in the discharge port of the pump
indicated in photo one which links to the horizontal passage. In my opinion this would give a very restricted flow via the relief valve. Can anyone who has an intimate knowledge of the operation of these
pumps enlighten me, please?

Jim

Hi Jim

On earlier pumps that is just the drilling to prime the return side of the pump, as you note a relief would have to be a larger passageway.

Thanks Duncan, that's confirmed what I thought. I was confused as I didn't see how this base plate would have been drilled like this, as it has been cast and machined to accommodate a relief valve.
It was also surprising that the refurbishment didn't pick it up. I managed to get hold of another late pump and found as you suggested that the hole was much bigger (see photo).
Unless anyone else has any better suggestions, I will drill a hole of the same size and see what happens.