SS rocker oil lines

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jseng1

jseng1

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The available SS rocker oil lines have only a 2.3mm/.090" something hole in the banjo fitting. The original stock banjo fitting has a .110" hole The spindles have a 1/8" through hole and the spindle outlet holes are 3/32" So is one .090" hole large enough to feed the rockers? I think so but I bet there are other opinions.
 
Just my thought : smaller hole means more pressure , and thus less flow , but which one is most important in that area ??? just think less flow up in the head (rocker spindles ), more flow in the pump (and in the big end)....:confused: ????
 
Two things occur to me, Norton did not provide much intake side oil drainage and intake is the where oil smoke issues arise so seems Norton put a number of volume restrictions in path so not to 'over' oil. The other thing is not allowing too much oil pressure/flow to be stolen from maintaining rod big end pressure/flow needs. When comnoz put tiny holes in cam lobes he next had to build a 3rd+ large capacity oil pump. Could make external intake drain to tolerate more head flow then put a valve in the feed to close down again till oil pressure seems good enough. Lubrication is not the issue in heads nearly as much as cooling springs, so provision for extra cooling of head flow makes more sense to me.
 
Jim,
IIRC someone posted some information about a short restriction in an line or hose due to a proper size fitting. It doesn’t really affect the volume/pressure much. It’s a ratio of total hose length vs the restriction length.
I have had a SS AN-3 with a cross over since I bought the bike in 1990 and have not had a problem. I have been running drilled rockers for about 5K miles and have not had an issue with that. There is always plenty of oil under the valve covers when I look.
If you think the fittings are too small it’s no big deal to make up a line using AN-4 hose. I’m pretty sure you can get 10mm banjos in AN-4 size.
Pete
 
Well said, Hobot.

Someone told me that the oil gallery between the two rocker spindles can be drilled to connect the two such that both sides then can be fed from one side, eliminating need for the connection up and over the head. Is that a good idea? Maybe do that but step up the supply line and banjo IDs?
 
jseng1 said:
The available SS rocker oil lines have only a 2.3mm/.090" something hole in the banjo fitting. The original stock banjo fitting has a .110" hole The spindles have a 1/8" through hole and the spindle outlet holes are 3/32" So is one .090" hole large enough to feed the rockers? I think so but I bet there are other opinions.
Click to expand...

The amount of oil flow from a 0.090” orifice supplied with 10 psi pressure from 50 wt motor oil at 100 C (20 cps fluid) would scare you as it would be in the multiple liter/min range. So to address your question about the 0.090” orifice vs the 0.110” orifice, it wouldn’t make any difference for this application, as the restriction limiting oil flow in the system is elsewhere, either downstream of the subject orifice, or there is much less than 10 psi pressure at the banjo during operation.

If you don’t believe me, make a simple test rig consisting of a fluid reservoir that can be pressurized, an outlet valve, and an outlet fitting that can be fit with different size orifices. Fill the bottle with your desired fluid, pressurize, keep a stop watch and catch can handy and open the valve. Be ready for some serious flow (and ensuing mess).
 
I can remember reading somewhere that the dunstall Norton's had a 20 thou restriction going to the head
 
<--That has had a braided-stainless rocker oil line since the '80s when it was last refreshed. Never had or heard of a problem and they cost twice as much as they did back then. I doubt they could sell one if the stainless lines caused problems.
 
xbacksideslider said:
Someone told me that the oil gallery between the two rocker spindles can be drilled to connect the two such that both sides then can be fed from one side, eliminating need for the connection up and over the head. Is that a good idea? Maybe do that but step up the supply line and banjo IDs?
Click to expand...

I did it with mine. Ran the line to the right hand side using a home made banjo that an AN 4 fitting screws on to. Made a similar setup for the left hand side which will be plumbed to a pressure gauge.
 
Surely the biggest restriction is the small clearance between the rocker an the spindle and the small feed hole drill in the rocker . Or am l missing something?
 
toppy said:
Surely the biggest restriction is the small clearance between the rocker an the spindle and the small feed hole drill in the rocker.
Click to expand...

Yes, but there are four of them.
 
xbacksideslider said:
Well said, Hobot.

Someone told me that the oil gallery between the two rocker spindles can be drilled to connect the two such that both sides then can be fed from one side, eliminating need for the connection up and over the head. Is that a good idea? Maybe do that but step up the supply line and banjo IDs?
Click to expand...

Actually you have to drill the inlet rocker spindles. Here is one thread relating to the subject..


https://www.accessnorton.com/NortonCommando/drilling-a-rocker-shaft.21023/#post-313499

I think the only advantage is the removal of possible failure points.


Cheers,

cliffa
 
When Norton went to 6 start pump flow they had to reverse spindle install to 'severely' restrict head flow or the returns of smokers under warrantly would put Norton out of business a decade sooner. The required restriction has nothing to do with how much flow supplied to head so waste of time/money effort/intelligence to increase hose size, unless also increasing intake box drainage yet not so much that low/mid rpm crank pressure/flow suffers. Lube is not the issue only oil and air cooling is. Logic implies shifting issue to plumbing head oil cooler and maybe a bypass toilet paper filter to boot. IIRC @ 6000 rpm about 3 gal/hr get to head and high 20's gal/hour to crank.
 
At 6000 RPM, only 3 gal/hour to the head?

I'm in the midst of a rocker line oil cooler project (to help oil's life) and if that's true, then I'm spitting in a hot frying pan.
 
xbacksideslider said:
At 6000 RPM, only 3 gal/hour to the head?

I'm in the midst of a rocker line oil cooler project (to help oil's life) and if that's true, then I'm spitting in a hot frying pan.
Click to expand...

It would help the oils life perhaps, but it would help cool the head and it’s contents. And the slow rate means the cooler would be more effective.
 
jseng1 said:
The available SS rocker oil lines have only a 2.3mm/.090" something hole in the banjo fitting. The original stock banjo fitting has a .110" hole The spindles have a 1/8" through hole and the spindle outlet holes are 3/32" So is one .090" hole large enough to feed the rockers? I think so but I bet there are other opinions.
Click to expand...

It is a well established principle in fluid mechanics, that a small reduction in tube diameter results in an insignificant (<5%) reduction in flow, providing the length of the reduced diameter section is short. Short is relative, and is usually defined as < 10 times the reduced diameter. Taking the banjo hole diameter as 0.090, ten times that diameter is 0.9 inches. Most likely the length of the reduced section inside the banjo is much less than 0.9 inches. This is the theory .... WZ507 above states the practical. Moreover, as Toppy says, the significant restriction is the drilling and shaft/bore clearances in the rocker .... even if there are 4 of them.

If this does not allay your fears, consider that the oil feed lines to the oil junction block on the 750 machines are 0.312 diameter, but the internal diameter of the ports in the oil junction block, and the internal ports on the timing cover are only 0.188.

Therefore you can sleep well tonight.

Slick
 
Thanks and well said Slick I have to note, though, that there are four banjos on the Venhill SS kits and each has a 1” long small diameter nipple


Just trying to reduce degradation of oil due to high temps before it drains down to the lifters/cam.
 
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