Different approach

Just a bit of an experiment I have been working on for a while






Eight start worm drive gear for the oil pump, reduces the reduction from 2.3 : 1 to 1.75 : 1
The idea came to me after much head scratching looking at the oil pump realising there is very little scope for increasing pump capacity within the limits of the timing case and remembering that if we are increasing delivery we must also increase the scavenge side of the pump, so this idea follows on from the factory solution from when they went from the four start drive of the Atlas to the six start drive of the Commando. Of course the downside to all this means that the pump speed will go from 3260 to 4285 at maximum engine speed of 7500 rpm, I am comfortable with this as 5000 revs is common for small industrial gear pumps.
As I said this is an experiment, Comments please!

Jolly good effort Fredful, what testing plan do you propose? Can you run it via, say, an 11,000rpm angle grinder & see what happens?

Awesome! Where can we get the kit to do the same?

gtiller said:

Awesome! Where can we get the kit to do the same?

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Gotta make sure it dosent self destruct before these go for sale, do a side by side test comparing oil pressure, flow, temp, wear characteristics and stuff.

J.A.W. said:

Jolly good effort Fredful, what testing plan do you propose? Can you run it via, say, an 11,000rpm angle grinder & see what happens?

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put it in the Commando and run it while keeping an eye on the pressure guage, remove it and check for wear or other adverse events.

very good, I certainly cant see any problems , interesting to see it in action , pressure, scavenging etc,
I reckon you would be on a winner there, production cost in OZ may be the killer.

Never heard of a four start. My 1949 engine, 1951 & 1952 model 7's, 1959 88 engine and my early atlas' are all 3 start. I tend to look after the condition of the pump rather than worry about speeding up a junk pump. :mrgreen:

I like it. Looks great. Machining gears has always been something I would like to learn.
If you decide to sell them and the price is reasonable, I would be interested in 2 or 3 sets.
I also have lots of stuff to trade.

I would not like to see my pump doing those revs , what sought of Industrial gear pump and scavenger are you refering to that do these revs . I do not see the need for more flow . The existing oil galeries and lines are sized to the pumps out put at the current gearing . If yoy increase the volume and do nothing else what are you going to gain . The rule of thumb is for any given fixed displacement pump that you require about 5 times the pumps max out put capacity volume in the reservouir for natural heat disapation cooling . With out the aid of an oil to air cooler you would generate more heat and foaming of the oil due to its velocity caused by more flow . pressure lines should not exceed 6 M/SEC and the inlet about 0.9 M/SEC or 3 FT/SEC if your not metricated . By all means do it but why and for what benifit apart from excelerated wear to the lube pump , Thats my two bobs worth (sorry metric 20 cents worth )Norton Dave .

In an earlier thread "commoz" made a new oil pump for his bike with better tolerances that gave him about 40psi at idle and 60 at higher rpms, with the stock drive ratio, this is to the best of my memory.

Everyone knows that the higher speed at which any machine runs, the less efficient it is at doing it's intended job. There are so many people who have run Norton motorcycles on the road and on race tracks reliably with stock pumps and gears, that this seems like a solution in search of a problem. One more example of how someone sets out to build "the ultimate Norton", but when they are finished replacing the frame, gearbox, engine cases, wheels, crank cylinder head etc. there is nothing left that is Norton, and nothing left that is vintage.

This has been done over and over again for decades. It made sense in the 40s thru 60s when Nortons were contemporary and you could not buy a 750 Honda, but it does not make any sense now as in the end you have neither a vintage motorcycle, nor a modern one.

If I go to a show or vintage race I want to see and hear vintage and historical motorcycles, not wet dreams. Put your Norton together with stock parts and common sense and it will be reliable, get good fuel economy and have enough power to break any law you care to break.

Awesome concept and creation Fastfred. Hmm, the oil pump snout is a weak leak for taking higher drive forces but may tolerate your 8 start. If there was less oil feed resistance, say like oil jets, then maybe the pump will only flow more oil not more pressure, and would be an elegant solution for Peel to try. Crank spin creates its own big end oil pressure if oil can be feed to it fast enough, head don't need but a sprizt of oil to help cool springs and such and cam gets splash and drain oil enough as is [except dry start ups or slow idle]. It may heat oil more by its stirring shearing friction but Norton's arn't known for over heating their oil except in extreme conditions that somehow burn more fuel power. There was a post recently with an oil pump tester outside engine that showed its leaks spraying out, so might be good to see what faster spun pump does, spits out forceful jet or just air foam.

To those who have studied such things, how will this affect perhaps the most critical point in a Commando engine: the con rod big end bearing / crank journal interface and it's proper lubrication through the rev range and load?

I am not a pump specialist or a fluid dynamics smart guy and definitely not a gear machinist, but the concept is sure interesting and those new gears look great. Can't wait to read about actual data and engine/lubrication/temperature behavior.

If you want to make something really useful make a new oil pump that doesn't leak.

8 start is brillant leap of insight to me. If it can supply say 1/3rd more oil flow volume then I'll buy your spares and save a whole lot of extra pump and plumbing on Peel's deal. Norton had to flip the rocker spindles to stifle head over oiling so wonder if may have to narrow it down further with an 6 strart.

Doing some more calculations relating to pump flow etc, I have only used the delivery side for the purpose of these calcs.

The volume of the pump in cubic inches per revolution = .0525

reduction from the crank to the oil pump - six start worm = 2.33 : 1 eight start worm = 1.75 : 1

volume per rev divided by reduction factor - .0525 / 2.33 = .0225 ci per rev .0525 / 1.75 = .03 ci per rev

volume at 3000 rpm six start worm .0225 x 3000 = 67.5 ci eight start worm .03 x 3000 = 90 ci

volume at 7500 rpm six start worm .0225 x 7500 = 168.75 ci eight start worm .03 x 7500 = 225 ci

conversion factor for cubic inches to litres 1 ci = .01639 lt

so at maximum rpm 7500 the pump with six start will flow 2.77 litres per minute, while the eight start will flow 3.69 litres per minute

according to my workshop manual the commando oil tank has a capacity of 2.8 litres so the standard pump will move the entire contents of the tank through the engine in one minute at 7500 rpm

another factor worth looking at is the horsepower required to drive the gear pump, the formula looks like this - GPM x PSI x .0007 = HP

with the full revs factored in for maximum oil pressure of 80 PSI the figures for the six start pump are .04 HP and for the eight start .05 HP

all these formulae are available on the net and the factors I have used are assuming pump efficiency of 85% that you could expect from a good quality commercial pump,
in reality the Norton is going to be on the less efficient end of the scale, I have not included the scavenge side of the pump in the calculations as the only work it has to do is push the oil through the filter back to the tank.

Very informative FastFred. I don't see the need of more oil pumping for ordinary use as the most long range enduring examples did it on factory oil flow and exam of Trixie Combat lifters-lobes showed better than pristine installed surfaces w/o exactly babying her for 8000 miles. Peel could make use of more/higher psI oil flow for piston cooling jets which need a minium of half a liter/min each for ~100'F cooling. So if engine needs/consumes ~2.5 l/m at max rpm then your pump would have about right excess for piston jets, which are only needed to come on at hi throttle rpm. The fancy external 12v oil pump from RBRacing I'm looking at costs $250, They use it to feed turbo's on Harleys and Hyabrusas. The sump size w/o back pressure should double the feed side flow, which is also useful feature to Peel if it could pump out the excess oil jet volume w/o need of another less costly low pressure 12v sump pump.

Whatever turns your crank. Or lubes it, in this case. I don't have a clue whether or not it is going to be beneficial, nor do I care to debate whether or not this sort of thing belongs on a vintage bike. I just like to see somebody who says "what if" and then takes the steps to find out. Even a failed experiment yields useful information. I will be standing by for the road test report! It's amazing how many projects I have done over the years just to see if I could pull it off. This is not the sort of thing most of us have the tools or the knowledge to accomplish. Even if you just hang it on the wall, you done good!

Russ

Excuse me Fredful FYO , but 1 cubic inch to cubic centermeters is cubic inches to cubic centermeters multiply 1 cu.inch x 16.38706cm3 so one cubic inch equals 16.38706 cm3. As for hp to drive a fixed displacement pump flow in US/Gallons x pressure in LBS/per square inch divided by 1714 =( HP = PSI X GPM DIVIDED BY 1714) do not forget pump loses and inefficiency gear pump would be about 75 percent efficient. Your formula states cubic inches to cubic centermeters factor .01639 ????? Norton Dave .

When I was trying to increase the oil pressure and flow I make a copy of the original pump with an aluminum main body and aluminum bronze end plates. I made new gears that were 1/16th inch wider and a much closer fit to each other and the housing. The pump has over 75,000 miles on it now and still maintains at least 40 psi at hot idle.

I will be interested in how running the pump faster works out. It could sure be easier than building a new pump except that I don't have a way to cut helical gears . Jim