I have read most of the information I can find about Pilgrim pumps and their operation on Scotts and feel I have a reasonably good understanding of them. However there are still a couple of things I dont quite understand. They are :-
1. Does the ‘timing’ of the two plungers in the pump in relation to the worm drive of the pump make any difference? They are supplying oil to the seperate sides of the engine and cannot be timed to the position of the engine cranks as they revolve – especially if you have a reduction gear fitted as I have. So does it matter at what point they mesh with the worm drive in the pump body ?
2. If the oil is ‘sucked’ into the main bearings by the negative pressure in the crankcase caused by the piston going up and the opening
of the holes in the gland washers why does it matter how much oil is being delivered into the wells of the Pilgrim pump. – Isn’t this
just a reservoir to hold the oil supply and the glands regulate the amount going in ? – the same as drippers work ?
Or have I missed something obvious !
Your thoughts would be appreciated.
The meshing of the gears makes no difference. Just consider the Pilgrim to be a metering device rather than a pump.
There shouldn’t be a reservoir of oil in the pump well. Any oil that is delivered should be sucked away immediately. Too much oil in the well will overlubricate and create excess smoke and oiled plugs etc.
In a box of glands, I have examples with one hole, two holes, three holes, elongated holes, and slots…. I’ve little idea what the owners were trying to achieve, presumably “improved lubrication”, but I see little point in the extra holes and slots. If the oil is not building up in the pump wells then obviously it is getting into the engine perfectly well, provided of course, that the pump is delivering oil into the wells nicely, and there are no leaks in the pipework.
I see the SOC still revells in myth legend and fairy stories, first of all each plunger in a pilgrim pump has to be phased at 180 degrees to each other this allows an equal opportunaty to take in a measure of oil, if both plungers tried to take oil at the same time there could well be a bias to one side, the inlet ends are diagonally opposite, so when you align them without the worm in place you have to screw the worm in fully without moving the plungers.
A pilgrim pump is not just a metering device it is a pump that delivers oil to the engine, each plunger is double ended, one end pumps oil up to the beak and the other end pumps the oil that drips along to the main bearings, if you doubt this just slacken the pipe joint at the elbow and see the ensuing mess inside the crankcase unaided by suction, if a Scott engine could produce enough suction in a split second when the gland holes align to pull cold oil through a foot of copper tube then that suction would empty your float chamber in a second, if you bothered to read the book of the Scott it would tell you that the pilgrim pump delivers oil under pressure to the main bearings. Also please note pilgrim pumps have been fitted to all manner of different bikes a lot of these are 4 strokes = no suction here so how do they work?
Over the years Scotts have fitted all manner of different oiling systems and for these they have developed glands with different hole positions so be aware you cannot just change the oiling method without fitting the corresponding glands.
Alan Noakes. email@example.com
What you say is true, Alan, but how do you explain the satisfactory performance where Pilgrims have been converted to drippers I.e. not pumping , without changing the glands?
When you convert to a dripper , effectively gravity is feeding the beak via the metering screw, the lower crank case suction pulse is then drawing the oil through the gland and into engine, does it work? is it more efficient than the complete pump ?
The main failing of the pilgrim pump is it’s lack of ability to draw or suck oil into itself, in other words no scavenge , if oil is driven under pressure into the pump the pumps output becomes more consistent, we then get around to the problem of the glands only allowing the engine to scavenge the oil for a small portion of it’s rotation, easy, remove the glands and fit oil seals, as soon as there is negative pressure in the crankcase oil will be drawn through the oil line ,into the engine
Non return valves needed ?
Thank you all for the replies. They have certainly given me lots to think about.
It is obviously quite an emotive subject !!
Non return valves needed ?
WELL I’ve not found they are needed, the system I have described has been running since the winter, i did get a pair but found they were not needed, the system seems to run quite happily without them
Barrie is absolutely right non return valves are not needed. I have been running Scott’s since 1962 some more successfully than others. My latest engines built 1991 have proved very reliable with direct feed to the mains using GACO type seals one being raced 91 to 02 and my Brum continuously on the road, not big mileages but enough to be certain that all is well. The engines carry various mods which if anyone is interested I am happy to advise.
Both machines have been timed at 103/2 mph, and although the racer is ” under the bench” the Brum is as I said used regularly.
Hi Dave, the reason drippers seem to work regardless of wether glands or no glands are fitted is the fact that gravity plus crankcase suction moves oil further than crankcase compression resisted by gravity could push it backwards. my previous reply did not mean that there was no suction present in the pipe only that the suction could not hoover out oil dripped into a pilgrim pump with a plunger in between the oil and the engine. My reference to different types of glands made by Scotts for different types of oiling systems, was only to show that when Scotts changed from drippers to pump feed they decided that better results were obtained by changing the hole pattern in the glands, and I am sure that had they decided to go back to drippers for the Flyer engines they would probably have altered the glands once more, I did not mean that drippers wont work with the standard glands in a Flyer engine, but if you have a 3 speed super engine with Best and Lloyd pump and want to convert to drippers then alternative glands are available. My personal view is that glands are an unnecessary nuisance and most of the oil centrifuges out from behind the gland regardless of the hole pattern anyway. The current trend in the club is that drippers are the answer to all ills, but they will only allow a fixed amount of oil to enter your engine and must be used in conjunction with a petroil mix, a good pilgrim pump will increase delivery with engine speed but even this is not good enough and would still require oil in the petrol, Scott owners seem to have forgotten that Scotts recommend that for fast road work you have to stop and open up your pump settings this would include drippers as well. I am so glad that my own Scott runs entirely on petroil with no weird oil system present. Alan Noakes. firstname.lastname@example.org
Hi Shipley Squirrel,
You are being fed some myth and legend. Brian Marshall is correct in saying the gland holes are adequate and don’t need to be modified.
A Scott engine can certainly suck all the oil delivered from the beak when the gland holes align. Nothing to do with your float chamber performance, it has a breather hole anyway. My 1932 Flyer sucks all the oil instantly from the wells. It doesn’t pump the oil, as I clipped the plungers on the outlet end, which means I turned a groove right round the plungers in line with the hole so that the end of the plunger can’t pump as it is open to atmosphere at all times via the small breather hole in the pump body which is just below the sight cover and it has nothing to pump against. With an unmodified plunger the hole isn’t necessarily open to atmosphere every time the engine tries to suck oil. If you doubt this, check with Gerry Howard the Pilgrim pump and Scott lubrication expert.
We also have to realise that oil doesn’t flow only for that microsecond when the hole in the gland lines up with the hole in the cup. Once the engine is running there is a thin layer of oil that the gland is floating on, separating the two surfaces, and letting some more oil enter for virtually 360 degrees of engine rotation. That’s my theory anyhow !
Yes as you say the oil is delivered in pulses on a continuous basis. Also with the pressure created it easily forces itself between gland and cup faces and is centrifuged out into the main bearings.
Just over one year on —- Yes I know this is an old thread —
However, I was having problems with leakage past the end cover gaskets plus the wells filling up when stationary.
So, the pump comes apart, the ends are converted to “O”ring seals beaks removed and ball valves re seated.
All reinstalled only to find one side behaving as it should, the other seeming to be unable to pump the well dry.
I tested the pressure required to overcome the non return valves and found the working side was at less than 2 psi, the none functioning side needed in excess of 30psi to overcome the valve.
I doubt the pump is perfect, so I removed the NR valves and re-tried the system.
Everything seems to work as it should, when running the engine sucks the oil from the pipe, the wells empty.
I am running without glands, just using lip seals, I also run nylon tube so I can see what’s going on.