Singles oil pumps

[Paul Gasson]

I am trying to get my head around oil pumps for my 1950 NH project. I understand that around the year my bike was made, the factory increased the piston diameter on the feed side from 0.187” to 0.250”, my bike came fitted with the larger size piston but it’s all very worn. I inherited a couple pumps from my father and two marked 39 and 40 are 0.187” diameter, which makes sense. The problem is that I have one marked 34 and this has 0.250” on the feed side. What could this be from?

[paul.jameson]

The parts books consistently show 2212-29 as the spares number for the oil pump in the 1930s. We don't have a copy of the drawing for the pump, which doesn't help. The change to the larger diameter pump came once scraper rings were introduced on the pistons. With 3 plain rings, oil leakage past the rings is too much with a large bore pump. I do wonder if the 34 you are reading could possibly be 54?

[dave.owen]

Or the pump has been reconditioned with bigger plungers

[Roger Gwynn]

The pump with the larger plunger was introduced during 1949 and the engines so fitted were stamped with an 'X' suffix. As Dave says an earlier pump with large plungers has been re-bored. The Draganfly re-conditioned ones, of which there are hundreds out there, were all bored slightly larger than the 1950 version so one plunger would fit all. There are also triumph pumps that will fit with minor mods but most have the plungers transposed, pretty sure it is the TRW pump that is the right way round. Ariel did not usually change a part number if the later version was interchangeable with the earlier, there are 4 versions of the damper knob fitted from 1938 to 1958 and just the one part number.

[david.anderson]

just a note on the 49 oil pumps. The early small 1949 plunger pumps were stamped 49 whereas the larger 1949 plunger pumps were stamped 49A.
David

[BarrieSteel]

my 1949 ng has larger 1/4 inlet bore and x suffix stamped on case as Roger says.Having a rebore with a three ring piston no scraper,is this a problem as in parts book and piston has correct number 1664c-39, think the same w/ng type.

[Paul Gasson]

Here is a picture of the 34 pump with a 40 pump for comparison. The 34 item has the same size return plunger so if it’s been worked on by Draganfly, would they just over bore the feed side and leave the return? On the front of the 34 pump it has PATT APP FOR cast into the return cylinder, as I think they all do but also has PAT 325226 stamped on the feed side cylinder. There is also a letter D stamped towards the bottom of the return cylinder near the ball valve. No other pump I have has this additional marking.

Paul J’s point about over oiling gives me a problem because the older small feed pumps I have are worn out, if I buy a new pump from Draganfly (Hawker) or Morgo, it will have the large bore feed, if I get a pump reconditioned by Draganfly, I understand this will come back with a larger bore feed. I am in the same situation as Barrie, with new piston and re bore using three compression rings because these were available ex WD and am now struggling for an oil pump.

Picking up Davids point regarding marking, I have a spare pump for my 1950 NH project marked 50 as expected but the pump I took off the bike is marked 50A, any ideas what this means? It looks exactly the same and pistons measure identically.

[paul.jameson]

The oil pump is the best lubricated part of the engine. My test is to put some oil in the feed hole and depress the plunger. A decent pump will squirt oil into your eye every time (but I wear glasses) so be warned.

My Red Hunter uses a pump from 1938, still on small bore. I have done around 40,000 miles on the bike with that pump so far.

[nevhunter]

The Morgo's seem to be well made but don't go for too much extra oil flow. You can't just fit a triumph one either It has to be decked and the plungers shortened and the fixing screw holes slightly ovalised, Length of plunger affects the output also. Don't mix conical with cylindrical springs. The conical springs with the correct holders seem to work the best. Always fit new balls of the correct diameter. They wear unevenly and become unreliable at seating. Nev

[john.nash]

Paul J’s point about over oiling gives me a problem because the older small feed pumps I have are worn out, if I buy a new pump from Draganfly (Hawker) or Morgo, it will have the large bore feed, if I get a pump reconditioned by Draganfly, I understand this will come back with a larger bore feed. I am in the same situation as Barrie, with new piston and re bore using three compression rings because these were available ex WD and am now struggling for an oil pump.

I have a pile of oil pumps in the garage.
Did you want one ?

msg me or email madoc500@hotmail.com