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Re: 1928 Ariel Model C [Re: Magnetoman] #738869 06/16/18 5:12 am
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Richard Kal Online Content
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Hi MM,
Check out this link (from the AOMCC Document repository):
http://www.arielownersmcc.co.uk/mem...nts/Patent-254-890-Lubrication/index.htm

It has a cross sectional drawing, and detailed description of your (our) single stage pump.

It is Val Page's Patent submission for the 1926 (re-designed) engine; the same pump as used in my 27 engine & your 28.

Richard

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Re: 1928 Ariel Model C [Re: Richard Kal] #738870 06/16/18 6:03 am
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Originally Posted by Richard Kal
Check out this link (from the AOMCC Document repository):
Richard,

Thank you very much for the link. I must have found it months ago because I discovered yesterday that I have a copy of the patent drawing in my 'shop manual'. I didn't have the text, though. I've now downloaded, printed and read it and, unfortunately, it doesn't contain any dimensions or discussion of clearances.

There are differences between my pump and the drawing and its description. For example, the description says "An annular groove g is formed around the outside of the plunger housing and from this groove a port g1 opens to the interior of the plunger-chamber..." Such a groove would allow the pump body to be inserted into the engine in any orientation. No groove is in my pump because it has a mounting flange (with 'Front' stamped in it making it impossible to mount incorrectly...).

Attached Files
OilPump_patent.jpg (100.64 KB, 888 downloads)
Re: 1928 Ariel Model C [Re: Magnetoman] #738871 06/16/18 6:14 am
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MM,
I have accumulated 3 or 4 of these pumps; every time I have bought an inner timing cover, they have always included the pump assembly.
Is there anything you would like me to check / confirm?

If you pm your email address i can take pics & forward.

Don't ask me to paste pics on this forum; too bloody hard !

Richard

Re: 1928 Ariel Model C [Re: Magnetoman] #738873 06/16/18 6:23 am
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PM sent.

Re: 1928 Ariel Model C [Re: Magnetoman] #738874 06/16/18 7:18 am
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How does the flange attach to the bronze body?


1968 A65 Firebird
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1972 Norton Commando
Re: 1928 Ariel Model C [Re: Magnetoman] #738881 06/16/18 9:48 am
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Quote
Using the rear stand is a real pain in the back so a side-stand would be a very welcome addition. However, because it wasn't clear there would be room for a side stand I decided to gamble on an inexpensive "universal" clamp-on stand direct from India (rather than a marked-up Indian side stand from a domestic supplier). It arrived today, amazingly fast, and aside from the extra metal I got for free, which keeps it from retracting all the way, it looks like I'll be able to clamp it on the frame behind the primary case. A grinder will deal with the extra metal.


I can see you have been spoiled by riding thes here modern bikes with that suspension stuff ( will never catch on ).
Rigid bikes, having lower and solid foot pegs will quite happily stand with the foot peg resting on gutter, assuming you do have solid guttering over there. smirk


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Re: 1928 Ariel Model C [Re: Magnetoman] #738900 06/16/18 4:05 pm
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MM, do you think your rear stand might be angled back a bit much when supporting the bike? The reason I say this is that M20's are known for fracturing their rear stand lugs when they wear enough to get more than 5 degrees or so from vertical. It does put a big strain on a fragile part, and gets worse as the stand wears on its stop. You might want to add a bit of weld to the stop to put less strain on a part that could cause a bad day if it fractures. Just sayin'...

And, kudos to your efforts and best of luck on the ride.

Kevin

Re: 1928 Ariel Model C [Re: Magnetoman] #738915 06/16/18 5:18 pm
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Originally Posted by Richard Kal
I have accumulated 3 or 4 of these pumps;
Richard had more pumps in one of his photographs than probably exist in all of North America. The measurements he provided offline were invaluable in helping me determine my next step, which will be to make a new plunger from precision 5/16" drill rod. His measurements of three plungers show my current one is undersize by 0.0006"-0.0008".

I'll be repeating my measurements today, but assuming I get the same results as yesterday my oil pump's ID is 0.0002" over being precisely 5/16" (0.3125"). Assuming the pumps left the factory at 5/16", and using Richard's measurements of his plungers, the original clearance would have been 0.0001"-0.0002". My current clearance is 5-10x larger than that, leaving too much room for air to leak past and thus the vacuum to be too low at low rpm.

Precision 5/16" drill rod from McMaster-Carr is specified to be (+0, -0.0003"), which means the clearance could end up 0.0002"-0.0005" depending on which end of the tolerance it has. Because of that, I'll also order 0.316" rod.

Originally Posted by gunner
How does the flange attach to the bronze body?
I don't know (yet). I applied as much torque to my clamp as I felt safe doing but the flange didn't budge. I haven't removed the gasket yet to examine the joint to see if it appears to be brazed.

Originally Posted by BSA_WM20
I can see you have been spoiled by riding thes here modern bikes with that suspension stuff
You bet I have. Life on the Ariel will be complicated (and painful) enough without having to try to preplan my stops to always have a suitable gutter or rock waiting for me.

Originally Posted by L.A.kevin
MM, do you think your rear stand might be angled back a bit much when supporting the bike?
Hmm, I hadn't noticed that. Thanks very much for mentioning it because otherwise I likely would have remain oblivious, but now that you did the large angle is pretty apparent. In light of this I realize it does go over center with a more serious 'clunk' than is reasonable. I found photos of several Ariels on line for comparison and mine definitely has more angle to it than those do. I've attached an overlay of one of them. I'll inspect the stand and lugs for signs of wear or other problems and take corrective action.

I'm grateful you noticed this problem, but the disturbing thought this brings to mind is, what else did I (and others) miss?

Attached Files
RearStand.jpg (41.45 KB, 827 downloads)
Re: 1928 Ariel Model C [Re: Magnetoman] #738920 06/16/18 6:05 pm
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This is a fascinating learning curve in oiling technology. Thanks MM.

Looking at that patent diagram (which is probably earlier than your slightly modified version), what Ariel seem to have done is to secure the "vacuum" side with O rings either side of the port. They don't seem to have been much concerned with the "pressure" feed to the crank.

I suspect that this pump works more as a vacuum pump (with regard to the drip supply), than an oil pump in the modern sense.
(By the way, are you sure about piston vs port diameters changing pressure?).

I think the pump will send any oil available to it, down the line to the crank.

Imagine a situation where no oil is being delivered from the tank feed. I am sure this has happened many times without catastrophe, and I'm sure the designers of these engines allowed for that, otherwise there would surely be warnings like !!! stop at once!!!.

Of course, a reserve was built in, in the timing case. This allows a reserve supply to both the TS bush and B/E etc.

It appears from your pics that the oil pump is below that oil level, and the piston would have oil behind it to provide a seal for drawing air, so is a tighter fit needed?


As you said, they were cleverer than we give them credit for, coping with the technology of the time. Actually that does them down, they were close to the leading edge, say with Avro, Saunders & co.

How is the sight glass used? Do you maintain some level of oil in it when running?

Surely in steady state, 1 drop in = 1 drop out? And the next drop is only drawn when the vacuum regains the necessary level?

Such a system is fascinating! Great stuff MM!

Re: 1928 Ariel Model C [Re: Magnetoman] #738947 06/16/18 11:41 pm
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Re Koan58's astute observation "They don't seem to have been much concerned with the "pressure" feed to the crank."

There needs to be a positive seal between the inner timing cover discharge port (oil delivery from the pump), and the oil gallery in the the crankcase otherwise oil will bypass into the crankcase. The amount of leakage will depend on the clearance between the two ports. It could be measured using Plastigauge, although I didn't bother to do this.

I made a gasket, which will do the trick. Alternatively, an o-ring would be perfect but requires spotfacing the casting.

No gasket is shown in the spare parts listing; what did the old - timers use?

Richard



Re: 1928 Ariel Model C [Re: L.A.kevin] #738951 06/17/18 12:24 am
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Originally Posted by L.A.kevin
do you think your rear stand might be angled back a bit much when supporting the bike?
Kevin,

Thanks again for pointing that out. As you can see from the first photograph the legs are bent enough near the top to have cracked the paint. I measured one of the on-line Ariel photographs, determined that the angle between the top frame tube and the stand should be 105-deg, and made a cardboard template. But, before doing anything else I took the stand to the hydraulic press and removed the bend(s). Both legs were bent in the way apparent from the first photograph, but also side-to-side in different amounts. Several setups in the press got the stand back to the way it needed to be.

As the next photograph shows, with the bends removed the pads on the stand don't line up well with those on the frame (they didn't line up any better before I straightened it). Perhaps it isn't the correct stand for this bike(?), although it fits the bushings on the frame and has the correct length to reach the clip in the mudguard. Or maybe just poor quality English workmanship...

Anyway, with the bends gone I used my template to adjust the stand to the correct angle and determined spacers ~1 cm thick would be needed. Since I knew there would be some amount of cut and try in getting the angle correct I decided to use 1/2"x1/2" brass for the spacers rather than steel. I cut the pieces to length and silver soldered them on the stand, keeping the flame away from the brazed lugs and only getting things hot enough to just melt the silver solder.

With the brass pads in place it took several trips back and forth between the bike and the vise until I got the brass filed to give me the 105-deg. angle I needed. For present purposes etching primer and gloss black paint would be sufficient so that's what I used. So, a job I didn't even have until Kevin spoke up this morning is now done.

Attached Files
RearStand01.jpg (93.23 KB, 778 downloads)
RearStand02.jpg (89.31 KB, 784 downloads)
RearStand03.jpg (63.22 KB, 776 downloads)
RearStand04.jpg (91.33 KB, 776 downloads)
RearStand05.jpg (85.63 KB, 768 downloads)
Re: 1928 Ariel Model C [Re: Magnetoman] #738953 06/17/18 12:32 am
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I noticed it a few days ago when you first showed photos of the bike, and was afraid I was going to come off over-critical and was reluctant to say anything. I'm glad it worked out and I look forward to you winning your class on the Cannonball.

Kevin

Re: 1928 Ariel Model C [Re: Magnetoman] #738969 06/17/18 8:11 am
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What do the feet on the stand look like ?
I have welded the ends on the M20 quite a few times then put a nice curve in there.
I do it by eye but one prone to calculations will no doubt calculate the optimum curve for the arc of the stand.
It does make a big difference to the difficulty of putting the bike on the stand.

Starting the bike on the stand while sitting on it will tend to bend it much like it does starting a modern BSA with the bike on the side stand while on the bike
After that is is just a matter of positioning a lifting handle that is in the correct position for your arms.
Before fitting that extra long rear rack, the M20 was a breeze if standing behind it and using the middle mudguard stays


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Re: 1928 Ariel Model C [Re: Magnetoman] #738986 06/17/18 2:14 pm
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Originally Posted by BSA_WM20
What do the feet on the stand look like ?
They're arced.

Originally Posted by BSA_WM20
just a matter of positioning a lifting handle that is in the correct position for your arms.
Lifting handle? Standing behind it, or on the side but at the rear, with one foot holding the stand so it doesn't slip on the pavement while lifting the ~150 lbs. of the rear of the motorcycle using the package tray, is a feat of gymnastics as well as strength. Hence, my plan for a side stand. Even though the one from India must be made of Kryptonite and will add 10% (estimated) to the total weight of the bike, and make it ride at a permanent 10% lean angle.

Originally Posted by L.A.kevin
I noticed it a few days ago when you first showed photos of the bike, and was afraid I was going to come off over-critical and was reluctant to say anything.
People shouldn't worry about being critical of anything I'm doing. Pointing out a GPS unit that doesn't belong, lettering that's too big, or a stand that's at the wrong angle -- even if I think a comment doesn't apply, it would be acid off a duck's back. It's easy for me to get caught up in the details and miss seeing something "apparent," like the angle of the stand, so I'm grateful for helpful observations made through other eyes.

Looking at photos of the Ariel now is like a 'what's wrong with this picture?' image after spotting the mistake -- once you pointed out the angle of the stand it was impossible not to notice. Anyway, even though fixing it wasn't on my to-do list for the bike first thing yesterday morning, I added it last night so I could cross it off to help me feel like I'm making progress.

Re: 1928 Ariel Model C [Re: Magnetoman] #739013 06/17/18 9:53 pm
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Referring to the oil pump diagram:
the cavities and clearances around the rear end of the pump body suggest to me that more is going on at that end of the pump. I suspect it is concerned with lubricating the (mainly) air pump.
As you say, it will be pumping air most of the time, between occasional drips. The piston of course needs lube during these dry spells, so where does it come from?
I think that is what the back end of the pump is doing, allowing access for oil to enter the spring chamber and be drawn along the piston.
This oil will also be enough to make the seal for generating the small suction required to the oil tank. I refer back to your use of grease as a gasket in similar circumstances.
Though you have compared it to one side of a Triumph plunger pump, it differs considerably in the following respects:
Even the scavenge pump sees oil most of the time
The pump up/down strokes are both mechanically driven

The 1st point has already been covered, the 2nd is that the Ariel pump uses a spring to return the piston through the suction stroke. I would think that spring to be an important factor, especially at higher rpm, rather akin to a valve spring.
That you noted the bore was a little rough, the piston does seem to have a sharp leading edge, maybe a small chamfer/taper may help? Of course any mis-alignment can only be caused by slack in the spring flange/chamber.
I enjoy your contributions as they spread my thinking from the conventional, thanks.

Re: 1928 Ariel Model C [Re: Magnetoman] #739047 06/18/18 3:01 am
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Originally Posted by koan58
Referring to the oil pump diagram...
With only a few exceptions since I joined Britbike I've enjoyed the discussions with nearly everyone. However to repeat something I wrote on Feb. 3 in response to several of your posts:
Originally Posted by Magnetoman
to be clear, if someone insults me, repeatedly, I'm somewhat less inclined to have an interest in explaining whatever it is that interests them at the moment.
I don't want to go down that road again, taking the time to write explanations and then being rewarded for my efforts with insults. But, enough on that topic. Back to motorcycles.

Originally Posted by koan58
This oil will also be enough to make the seal for generating the small suction required to the oil tank.
Bronze makes a good bearing surface for steel so only a minimum of lubrication is needed and there's plenty of that in the inlet mist alone. Also, the inlet line to the oil pump is at a low relative vacuum so thick grease has no trouble sealing against the small differential pressure. However, the air in the small chamber on the inlet size can be at a higher relative pressure difference which could easily push past a film of thinner oil. The value the pressure reaches depends on the strength of the spring for the one-way valve whose spring constant I haven't measured as yet.

Thanks to today being Father's Day I've been with the granddaughters most of the day so I didn't have much time in the garage. But, I did get the rear stand bolted back on and finished modifying and attaching the side stand. As can be seen the side stand blends nicely with the lines of the bike so doesn't look too out of place. Minor tweaks of its mounting on the frame to result in a fairly small lean angle when parked will have to wait until the bike is sitting on the ground.

Attached Files
SideStand01.jpg (87.25 KB, 689 downloads)
Re: 1928 Ariel Model C [Re: Magnetoman] #739099 06/18/18 4:03 pm
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I have spent a while looking at the oil pump drawing, I think I get the gist now.
Its more like a fuel injector than a normal pump. In my mind at least.
I presume the piston is moved by a cam to the RHS in the drawing, it appears to show base circle and full lift position, strikes me that wear on the piston end / cam interface will change the compression in the pump, the original length dimension would be handy. it also bothers me that the return motion of the pump is by a spring, its the spring that does the vac part of the operation if I understand how it works correctly, a critical spring, best have a spare or two.

Seems weird that the metal flake got in there, it almost looks like it was meant to be there
Looking wonderful so far, you must be champin to get out for a thrash, i would trade your weather for an hour or two if it was possible, lovely and cool here, 12 C midsummer.


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Re: 1928 Ariel Model C [Re: Magnetoman] #739117 06/18/18 5:57 pm
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The value the pressure reaches depends on the strength of the spring for the one-way valve whose spring constant I haven't measured as yet.


To my eyes that spring looks rather feeble and possibly corroded. Springs used in one way valves often compress after years of service so I would try and get a spare, if available.

Regarding the side stand, I once used a similar one on my first bike a BSA C15SS. As a side stand it worked OK but had a problem with gripping the frame tube. As a result what started out as a 5 degree lean ended up as a 45 degree lean after a few days. Whether this was due to my youthful inexperience or simply a badly fitting part remains a mystery. I recommend you ensure the bolts are really tight to avoid slipping around the frame tube.


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Re: 1928 Ariel Model C [Re: Magnetoman] #739121 06/18/18 6:19 pm
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After studying the oil pump diagram, it appears to work as follows (and apologies to MM if this is rubbish):-
- the piston (c in the diagram) is pushed by a cam (e in the diagram)
- the large spring (f in the diagram) ensures the piston is constantly engaged with the cam
- when the piston moves to the right helped by the large spring, vacuum causes oil to be sucked up from the tank via the feed pipe j and orifice g1
- when the piston moves to the left via the cam any oil/air is pushed out through the one way valve h, outlet orifice i and pipe to tank k

I'm not sure what purpose the area g serves, perhaps some kind of oil/air return?

Anyway certainly a unique design and one I have never seen before.


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Re: 1928 Ariel Model C [Re: Magnetoman] #739128 06/18/18 9:16 pm
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Originally Posted by gavin eisler
I presume the piston is moved by a cam to the RHS in the drawing, ,,, the original length dimension would be handy.
Yes, the cam for the oil pump is in the form of a cylinder offset from the rotation axis (i.e. not egg shaped) that's part of the camshaft to the RHS of the drawing.

I'm still in the process of making careful measurements of the all the components of the oil pump, detailed enough that in principle I would be able to make my own duplicate if it ever came to that. The plunger is 1.734" long so it probably was on the workshop drawing with the fractional dimension 1-3/4". I say 'probably' because it was designed by an Englishman, after all, so I can't rule out the draftsman considering 189/256" to be a reasonable fraction.

I have steel rods of the necessary size for the plunger "in stock," but I've ordered water hardening tool steel (W1) for the pump so that I can harden the cam end for wear resistance. Actual work on refurbishing the pump is on hold until that tool steel arrives on Wed. or Thurs., but there are other things on the Ariel's to-do list for me to take care of in the meantime.

Originally Posted by gavin eisler
. it also bothers me that the return motion of the pump is by a spring, its the spring that does the vac part of the operation if I understand how it works correctly, a critical spring, best have a spare or two.
There are two springs in the pump. One operates the non-return valve at the bottom end of the pump (the left end in the drawing), and the other returns the plunger after each stroke. For the pump to rely on a spring for this latter task bothers me a lot. If there were the equivalent of only a partial seizure the friction could be enough to keep the plunger in its extended position and pumping would cease.

Originally Posted by gavin eisler
Seems weird that the metal flake got in there, it almost looks like it was meant to be there
In the photograph that piece of metal looks like the end of a pin, which at first I thought was the way the position of the collar was fixed for it to be brazed into place. However, the apparent shape was a coincidence because when I flicked it out of the groove and examined it under the microscope it was an irregular semi-spherical piece of metal.

Originally Posted by gavin eisler
Looking wonderful so far, you must be champin to get out for a thrash, i would trade your weather for an hour or two if it was possible, lovely and cool here, 12 C midsummer.
The excellent riding weather of the fall, winter and spring was largely squandered because I was hunkered down in the garage every spare moment working on the Ariel. Unfortunately, despite the heat of the summer days, my tour of the driveway a few days ago has me very much wanting to ride it. But, for now, the oil pump won't let me.

Originally Posted by gunner
Springs used in one way valves often compress after years of service so I would try and get a spare, if available.
Unfortunately, Amazon Prime shows them as 'out of stock'. Seriously, finding any spare parts for a 90-year old motorcycle is an adventure. Thanks to Richard Kal I now know the Ariel club of Slovakia -- yes, there is such a club -- has a list that shows they stock a reproduction of the main spring, but I don't see the one-way valve spring. However, I've measured the dimensions and spring constants of the two springs (5.5 lbs./in. and 3.2 oz./in., in case anyone is interested) so could wind my own if I were desperate.

Originally Posted by gunner
I recommend you ensure the bolts are really tight to avoid slipping around the frame tube.
Agreed. However, I'll have it adjusted to keep the bike nearly vertical so there won't be much force on the clamp-on bracket. My intended use will be for fuel stops as well as to hold the bike until I can reposition myself to lift it onto the center stand without having to manually balance the machine as I work my way to the back.

Originally Posted by gunner
I'm not sure what purpose the area g serves, perhaps some kind of oil/air return?
Patent drawings have to be done to a different standard than engineering drawings so it's not always obvious what is what. g is an annular groove that connects to the inlet g1 allowing the pump to be inserted into the engine at any angle. However, as implemented on my pump that groove is missing since the mounting flange eliminates the option of inserting at arbitrary angles. The are just two ways it can be inserted -- the correct way with 'Front' toward the side of the bike, or the way I did it the first time with 'Front' toward the front of the bike.

Re: 1928 Ariel Model C [Re: Magnetoman] #739136 06/18/18 10:57 pm
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"Bronze makes a good bearing surface for steel so only a minimum of lubrication is needed and there's plenty of that in the inlet mist alone. Also, the inlet line to the oil pump is at a low relative vacuum so thick grease has no trouble sealing against the small differential pressure. However, the air in the small chamber on the inlet size can be at a higher relative pressure difference which could easily push past a film of thinner oil. The value the pressure reaches depends on the strength of the spring for the one-way valve whose spring constant I haven't measured as yet."
As it happened, I hadn't actually asked for any explanations, I merely proferred some thoughts.
In the same vein, I would doubt the "inlet mist alone" exists.
The pressure required to open the one way valve does of course depend on the pre-load force of the spring. I imagine this is small, as it has to allow compressible air much of the time. That valve allows whatever is in the pump (air or oil) to be pushed into the crank feed, the nature of which has no resistance to flow. (that valve seems to be a disc, rather than a ball say, and may be worth checking.)
In a nutshell, the piston will push whatever oil/air in its chamber to the outlet pipe at full push into the cylinder. I think this is the easy bit to understand.
On the reverse stroke, the piston spring is enlarging the (now closed) chamber to something much larger, hence low pressure for the suction to the oil delivery system. Should that spring not be sufficient to return the plunger at higher rpm, was what I was throwing into the cauldron of thought.
I like to learn about the early times of lubrication technology, and I have enjoyed following this immensely. Please excuse any previous offence, I have no problem with apologising to you.

Re: 1928 Ariel Model C [Re: Magnetoman] #739141 06/19/18 12:22 am
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gavin eisler Online Content
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Further to wear on the piston end, the piston passes the inlet port in the floor closing it on the compression stroke, wear on the piston end will delay this closing and reduce the delivered volume, maybe stellite the piston end when you make the new one? You could check the dead space at the end of the stroke with plasti gauge to see how much room there is to play with.

Get in the piano wire , you have a lathe, This old Tony makes it look easy, https://www.youtube.com/watch?v=jAawhg6JtyY


71 Devimead A65 750
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Cagiva Raptor 650
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The poster formerly known as Pod
Re: 1928 Ariel Model C [Re: Magnetoman] #739148 06/19/18 4:22 am
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Magnetoman Offline OP
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Originally Posted by gavin eisler
maybe stellite the piston end when you make the new one? You could check the dead space at the end of the stroke with plasti gauge to see how much room there is to play with.
I could make the plunger -- the term used in the patent application -- from "ordinary" steel and add a Stellite tip. However, when W1 tool steel is flame hardened and then tempered at 200 oC (the max. temp of my oven in the garage) it will have hardness ~62 Rockwell C. That's actually harder than the ~45 of the Stellite 6 TIG filler rods I have.

I mentioned in an earlier post that when I used the split ball gage the walls of the housing felt a bit rough. The micrographs show why that was the case. Note that depth-of-field rears its head when taking photos at high magnification of features at the bottom of a deep hole (yes, I could have used Photoshop to stitch a number of photos together, but I didn't).

The housing consists of a ~0.4"-dia. bore near the top (mostly out of focus in the micrographs) and a ~0312"-dia. bore near the bottom. It's the clearance between the plunger and wall at the bottom that matters. All the real action takes place between the bottom of the intake slit (port g1) and where the plunger ends its stroke. As you say, minimizing the dead space (but not so much so that the plunger is in danger of making contact) maximizes the operation of the pump.

It would be easy to simply reuse the existing plunger because maybe it might be "good enough" for 4000 miles. However, deciding on a course of action to return it to condition at least as good as the best oil pump that left the factory takes time. To understand the present condition is why I took the time to take actual micrographs rather than grab images through an eyepiece of the one in the garage.

Note that the bore has a flat bottom at the bottom of the chamber, and creating a smooth bore that reaches to a flat bottom isn't trivial. My present plan, subject to change, is to modify the appropriate mandrel according to Sunnen's instructions to make it appropriate for honing a blind hole. Then, after honing the bore I'll measure the ID and make the plunger to fit, with the necessary few ten-thousandths of clearance. I'll do the rough finishing with standard lathe tooling and then sneak up on the OD with the toolpost grinder. If necessary I'll use a Sunnen external hone to create the final finish on the plunger.

As a note on the operation, the hole between the two chambers is 0.089"-dia. and when the one-way valve spring is installed it is compressed by 0.29" so since the spring constant is 3.2 oz./in. the force holding it against the hole is 0.93 oz. The area of the hole is 0.00622 sq.in. so the pressure needed to open it is 149.7 oz./sq.in., or 9.3 psi. The distance from the bottom of the inlet slit to the bottom of the chamber is 0.175". If 0.025" is allowed for clearance at the bottom of the stroke, and if the hole were plugged, the pressure would increase by 7x to 103 psi so the loss of "efficiency" due to the 9.3 psi needed to open the valve would be only 9%.

Attached Files
OilPumpBore01.jpg (51.67 KB, 540 downloads)
OilPumpBore02.jpg (49.96 KB, 546 downloads)
OilPump05.jpg (44.29 KB, 545 downloads)
OilPumpBore03.jpg (55.24 KB, 537 downloads)
Last edited by Magnetoman; 06/19/18 5:03 am. Reason: added another photo of the housing ID
Re: 1928 Ariel Model C [Re: Magnetoman] #739155 06/19/18 7:29 am
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gunner Offline
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I noticed there is a patent number stamped on the flange and decided to look it up. A full description of the pumps workings can be found At this link under the descriptions tab. Unfortunately there are no drawings available under the drawings tab.

This is probably the same info as posted on the Ariel Owners web site but which needs an account to login and view.

Last edited by gunner; 06/19/18 9:12 am.

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Re: 1928 Ariel Model C [Re: Magnetoman] #739162 06/19/18 11:00 am
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gavin eisler Online Content
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The roughness looks mostly circumferential, probably came from the factory like that, or the plunger has been spinning in operation?, i dont see many wear lines along the axis of the plunger travel, great pics .

Cleaning up the working end of the plunger bore, trying to imagine how I would attempt this without a Sunnen, perhaps a split Al dowel and lapping paste. Another lazier way to look at it, if the groove wear is circumferential it may act like a labyrinth seal, thats putting on the Optimist hat. Presumably the plunger bore was reamed to size at the factory.

Reading through the Ariel patent stuff there is an unfortunate Freudian slip, or is it?.This is a cut and paste from the patent site, note the use of stiction, rather than suction

"An annular groove is formed around the outside of the plunger-housing and from this groove a port proceeds to the interior of the plunger-chamber, such 85 port being so located that it is uncovered by the plunger during its suction stroke, whilst from the outer end of the said chamber a delivery passage proceeds into a radial delivery port in the outer PC portion of the housing, The part of the timing-gear box wall wherein the pmpunit is housed is provided with oil-intake and delivery passages which, when the unit is fitted in position, register respectively with the annular external intake groove in the housing, and with the delivery passage of the said housing so that, during the stiction stroke of the plunger, the intake port leading from the external groove into the plunger-chamber is uncovered to admit oil to the said chamber, which oil, during the delivery stroke of the plunger under the cam action, is displaced (after the closing or covering of the intake port by the plunger) through the delivery passage of the pump-unit into the delivery passage in the wall of the timing-gear box."





71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
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