Worn PW3 cam

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Just a thought but crankcases with one way valves approach vacuum . Is oil vapourisation different from what it would be at atmospheric pressures..In a vaccum water boils at room temperature .
 
oldmikew said:
Just a thought but crankcases with one way valves approach vacuum . Is oil vapourisation different from what it would be at atmospheric pressures..In a vaccum water boils at room temperature .
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I was waiting for someone to ask that question. I doubt one-way crankcase breather valves approach a vacuum, at least not on our Nortons but one of the advantages to reducing crankcase pressure (I mean serious pumping to evacuate the crankcase) is reduction of windage. Wind is comprised of air and when you reduce or eliminate the air, the oil droplets tend to fling and set rather than get "air" transported all over in a circulating load. Another advantage to significantly reducing crankcase pressure is increasing the differential pressure across the rings which I understand enhances the sealing of the rings.

In this instance, don't confuse vapor (vapour) with gas phase, two different animals.
 
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Dances with Shrapnel said:
No, a flood is not better. Rod bearings rely on a hydrodynamic wedge which occurs under controlled conditions of load, oil pressure, speed, viscosity, and probably a half dozen other thingies.
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Rod bearings do rely on oil flow amongst other factors but oil pressure is not one of these other factors in forming the hydrodynamic wedge, you would think that it was but the pressures within the hydrodynamic wedge are orders of magnitude higher than the oil pump pressure. The oil pressure is telling you the bearing clearances and the oil flow are correct for the wedge to form but the actual oil pump pressure has no contribution to the pressure within the hydrodynamic wedge.

A calculator for the hydrodynamic wedge pressure

http://www.calqlata.com/proddetail.asp?prod=00058

and pump oil pressure is not a feature you need to feed into the calculation to get the result out.
 
Agree and I was not referring to oil pump pressure, just pressure - see my post. Flow is an obvious component for if there is inadequate or no flow the oil would cook and turn to smoke.
 
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That looks like good oil IMHO.

25w70 is an interesting weight. I am a believer of thick (when hot) oil in our slack old motors.

But this oil makes me wonder, at what point does thick become too thick?
 
I use 10/60, it never gets thicker, it's like a 10 when cold and a 60 when hot but that is still thinner than a cold 10, a hot 75 would still be thinner than a cold 20. The difference between the 2 extremes will be less but the hot oil will be thinner, just not as thin as a 20/50.
 
kommando said:
I use 10/60, it never gets thicker, it's like a 10 when cold and a 60 when hot but that is still thinner than a cold 10, a hot 75 would still be thinner than a cold 20. The difference between the 2 extremes will be less but the hot oil will be thinner, just not as thin as a 20/50.
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I use a 20w60 currently, but am tempted by this 25w75 Penrite stuff. So was justa wundrin...
 
Fast Eddie said:
That looks like good oil IMHO.

25w70 is an interesting weight. I am a believer of thick (when hot) oil in our slack old motors.

But this oil makes me wonder, at what point does thick become too thick?
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I am wondering what was left out of the 20-50wt that Ken was using with what penrite recommended for Pre 1980 engines. It lists plenty of M/C:
Ariel
BMW BSA Douglas Ducati
Gilera Harley Davidson Heinkel Indian ISO
JAWA Matchless Motobecane Moto-Guzzi Norton
NSU Panther Parilla Rabbit Royal Enfield
Sunbeam Triumph Velocette Victoria Vincent
Regards,
Thomas
 
CanukNortonNut said:
Penrite has plenty of zinc.
Just for fun, I went on there website and scrolled through what they recommend for oil for a Norton Commando. They listed this:
https://penriteoil.com.au/applicati...MANDO&year=1974&fuel=PETROL0.8&vehicle=204017
The zinc numbers are higher as well as the Phosphorus, Mass %. It is also recommended for pre 1980 engines.
Ken, did you get the oil analyzed just to rule it out of the equation?
The mystery continues.
Thomas
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No oil anaysis done. Oil was doing well with no issues. As judged by the metallurgist. Very clean inside.
 
This coming winter, my friend is pulling apart his 128,000 mile, purchased new, never been apart 73 850 engine for a complete rebuild. Its going to be interesting to see that cam and followers.
Will post photos of it and anything else of interest from that engine.

Glen
 
worntorn said:
This coming winter, my friend is pulling apart his 128,000 mile, purchased new, never been apart 73 850 engine for a complete rebuild. Its going to be interesting to see that cam and followers.
Will post photos of it and anything else of interest from that engine.

Glen
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I will be looking out for these photos for sure.
 
Dances with Shrapnel

Don't misunderstand me - I am not suggesting pumping more oil into the crank case and I am not encouraging pressurized oil to the cam. What I am saying is that since the oil is already draining down the pushrod tunnels from the rockers - then you might as well direct it to the center of the cam lobes. The stock setup drains it down the chamfered side/corner of the lifters and sort of misses the lobe center.

This is not adding to the total amount of oil - just re positioning where the rocker oil drains to. Its a feature of the bronze tappet blocks and radiused BSA lifters. Ken Canaga turned me on to this setup when I was racing. The factory Norton dirt track racers were doing it. Ken showed/told me about the longevity of radius lifter cams compared to flat tappet cams and I was impressed. Below is a photo after a 5000 mile inspection. You can see some dark stain on the left lobe tip but everything else is clean. There is 40,000 miles on it now but no new photos.

Worn PW3 cam


Surely you don't object to oil dripping onto onto the centers of the cam lobes instead of to the sides.
 
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I asked my friend Ian what oil he used for 128,000 miles.
The answer was Pennzoil ,most of the time.
He switched to Pennzoil MC oil when the ZDDP numbers dropped on the regular 20/50 oil.
He is very regimented on oil changes, does them every 1500 miles.
I sometimes run 2000 or a bit more on the Norton. Might cut that down to 1500, the oil on the last change looked pretty black.
That might be because the right carb main jet /needle jet holder was nearly falling out!

Glen
 
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