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Crankshaft Oilways
#1
Hi All
I've recently bought a 1-1/2" Nippy crank (splash fed) that I intend on putting in the new engine I am building. When I look at it against the old 1-5/16" crank the oil ways and catch scoops that the oil jets aim lubricant at seem very small on the Nippy crank (see photos - Nippy crank with Con Rods attached, 1-5/16" crank without). Is this going to cause me any problems? Do I need to be extra careful about the aim of the oil jets? Has anyone drilled these holes out to enlarge them a little?
All advice gratefully received
Cheers
Robbie Confused


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#2
Normal Nippy oil ways.Have you had the crank and rods crack tested, wouldn't risk this without crack test specially if putting it in a genuine sports Crankcase.
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#3
I'm new to this but have an interest as my first Seven is a type 65 with the original crankshaft, which I'm assuming is the same as your Nippy crank.
Thinking about the centrifugal forces applying when the crank is in motion I would say the Nippy design was much more likely to channel a decent quantity of oil towards the bearings than the earlier version. Be interesting to know what the experts think.
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#4
I consider the size of the drillings in a Nippy crank are to small and probably a contributory factor to the reputation they have for running big ends. I enlarge the drillings and put a radius the entry point in the trough, others may view it differently it keeps me happy. Smile
Black Art Enthusiast
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#5
For what it might be worth, and of interest to anyone contemplating mod of conventional rods, in early edition of his textbook Ricardo disapproves of rods relieved as the photo. At least with heavier pistons, under the tension of high rpm tend to close and distress the bearing.
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#6
(28-01-2018, 09:02 AM)Bob Culver Wrote: For what it might be worth, and of interest to anyone contemplating mod of conventional rods, in early edition of his textbook Ricardo disapproves of rods relieved as the photo. At least with heavier pistons, under the tension of high rpm tend to close and distress the bearing.

I guess its always a trade off, less weight on the bottom end will equate to less strength. Interestingly my speedy engine rods are the same and each has significantly stretched at the little end hole. so much so that I have had to retire them.

I wonder if it is the other end of the rod that is the weak link rather than the big end. Have others had the same issue?
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#7
My Speedy rods had been bushed at the little end so I retired them and fitted Phoenix instead, I have a set of Nippy rods for another engine with slightly oversize little end eyes.
Black Art Enthusiast
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#8
All the Nippy/Speedy rods that I have had through my hands have been worn.
The wear always occurs top to bottom  I am pretty sure this is because of the little end eye being drilled for oil underneath with two holes, this is the thrust side.  All the modern rods only have a single hole in the top of the rod.
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#9
(28-01-2018, 08:38 PM)Robert Foreman Wrote: All the Nippy/Speedy rods that I have had through my hands have been worn.
The wear always occurs top to bottom  I am pretty sure this is because of the little end eye being drilled for oil underneath with two holes, this is the thrust side.  All the modern rods only have a single hole in the top of the rod.

Mine might have been worn rather than stretched, not sure I could tell the difference. In any event the Phoenix rods looked much more robust and help me sleep at night. The original crankshaft is however still in the engine and this does give me the occasional feeling of dread Sad
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