Mechanical Oil Pumps.

Neil,

Sorry for the late reply, I have just got around to finding this...for some reason ABC posts keep going to my junk. I keep telling hotmail...

Many thanks for the link. It may well have been your post that I recalled the information form. Photo 61 is the one that intrigues me most. Do you know any details on it? Why is the Best $ LLoyd vertical? What is the large pipe going to the magneto on the timing cover? Why is the feed pipe at the bottom? How does the oil react when the oil is drawn through by the suction of the engine - is there a mismatch of pressures?

All very interesting. I'm still not sure if it is worth it. I think the main advantages are that you get a continuous oil supply, rather than slugs, and back-up if a piston ring goes.

But many thanks for all the info,

Nicholas.

Hi Nicholas

They are all interesting questions. I do not really have any more details - sorry but my best guesses are below. I just took the photos because I saw the question on our website those years ago.
Why is the Best $ LLoyd vertical? Answer: It probably does not matter that it’s vertical, so maybe just done like that for convenience of attachment
What is the large pipe going to the magneto on the timing cover? Answer: On photo 51 it looks like it is just a breather. It is interesting to see that it is on the second bike too.
Why is the feed pipe at the bottom? Answer: As above, I do not think it will matter if it is above or below. What do other people think?
How does the oil react when the oil is drawn through by the suction of the engine - is there a mismatch of pressures? Answer: the screw adjusts the pressure downstream of the pump. I haven’t had my engine apart yet but it looks like the oil feed goes straight into a gallery that feeds the big end bearings. I cannot see there being any suction from the engine. Did you see the article I posted about configuring the oil feed? It said to “set up the oil for 20 drips per minute”? This suggests to me that there is no suction from the engine. It looks like gravity feed only.

Sorry I made a mistake. I just re-read the magazine article I posted and it doesnt say 20 drops per minute - that must have been what I read on an posted someone else put up elsewhere. I've got a request in to the VMCC on ABC stuff and if there is anything in that bundle when it arrives i'll post it. I haven't ran my bike yet as I want to read what I can before hand to avoid breaking anything. I have plenty of other bikes that need attention ha ha.

Be aware there are two common sizes of B&L MkII pump. On casual glance they look they same but are not. One is for engines over 1000cc and pumps up to 500cc per hour at 1000 rpm (pump revs, remember, not engine revs). The other is for engines under 1000cc and pumps up to 200cc per hour at 1000 rpm.

Most current reproductions appear to be of the larger size and you are likely to be plagued with over oiling woes if you fit one..

The pump shown on the Bob Thomas engine is the smaller of the two and one of the photos shows the actual pump setting which is rather lower than most people will expect.

As it happens my 1926 Matchless was fitted as standard with the smaller B&L so I am very aware if how difficult the smaller one is to find. I persisted with mine until the body was more pink Plastibond than original zinc die casting and was finally forced into fitting a Pilgrim as used on later vintage Matchless. Nothing wrong with either the Pilgrim or the B&L but as it is so prominent I would have preferred to stick with the factory fitted B&L. No such joy.

Finally, be aware that getting the flow rate just right for your engine is far more subtle than you expect. A pump is not a fit and forget item.

I came across an letter in The MotorCycle from 1921, in which Bradshaw is replying to criticism of the oiling system on the ABC. It made interesting reading.