Big End Oil Groove

[Hedd_Jones]

Jet feed is quite correct Tony, whilst I think the Ford T was dipper.

My father always refered to them as 'spit and hope' lubrication

[Bob Culver]

With the spray system dealing with a mix.  I suppose some arrangements could develop obstructive cushions of air.

(A few years ago the mods done by  Raymond Mays to extend the capture scoops on his racing jet fed Bugattit Brescia and so greatly extend the rpm limit was covered)

[Steve Bryant]

"One other consideration is the Type of Lubricant that you will be using .

Colin
NZ "


Colin I'll be using PENRITE, High Zinc "Shelsley Light" 20W60

[Tony Press]

Chris and Ian note that the Nippy crank had a single small drilling from the jet intake to the bearing - is this like the Phoenix 'jet fed' crank arrangement?

If I am reading it correctly Ian noted that the Nippy crank often gave rise to bearing failures.

As noted the Longbridge 'jet fed' crank had a quite long (three drilled holes) oil path with a 'reservoir' formed by the largish longitudinal hole in the crank.

Could this explain some of the bearing failures with the Phoenix crank ?

[Ian Williams]

Tony, you read in old 750mc articles that Nippy cranks run bearings due to the higher rubbing speeds, I do not agree with that, I believe the oil hole and pickup trough is too small, its only 9/64" and as I mentioned easily clogged.

[Bob Culver]

Hi Steve

Very experienced high mileage users on this Forum claim very adequate service from cheap multigrades. The 20-W is based on a quite low temp and 20W60 is thick at more normal temps and will sap “power”. For the first ten years of production cars would have run on non additive oil API SA. Then SB  for some,  this continued into the 1960s for most. Cyl wear was greater than today and main bearing wear notable in poor running conditions. Spenders may have in the later 1960s used the equivalent of API SC. Any modern oil  (not necessarily classic replicas)  will greatly exceed any of these API specs.
Engine wear in all cars greatly reduced from about the 1960s.
As it is likely the engine will devour some, and change intervals will be low in miles, fancy oils seem pointless.

[Chris KC]

I just can't resist a thread drift...

Agree with Ian, I can't imagine what Austin were thinking when they made the Nippy oil holes so small. Perhaps they were afraid the oil drillings weakened the crank? Which may explain the equally unfathomable Ulster-type screw-on external crank oil passages. My possibly completely erroneous perception is that by the time Nippy and Speedy came along Austin were eyeing up endurance events (hence the deep Nippy sump), which made oil supply for sustained high speed running all the more important.

I'm sure it's no accident Bob that engine wear dramatically increased as multigrade oils began to find favour (though there are without doubt other factors). The vast majority of engine wear occurs at start-up with cold oil; a condition which multigrades were specifically designed to address. Imagine a splash fed engine trying to pump around a straight 40 (or, God forbid, a 60 grade...) on a winter's morning. And those teeny little jets trying to squirt treacle at the crank...

There have been numerous discussions about oil grades on here and everyone subscribes to their own 'camp', so I won't labour it. Personally I've used a detergent 20W50 since time began and have no issues with it, though I suspect it's a little on the heavy side.

[Colin Reed]

HI Steve,
Your decision to leave out the oil grove I believe is the right choice as the reliefs on the split line will spread the oil film.
And Shelsley light which is a Mineral oil will be a good choice with the extra zinc and low detergent especially with no filter

Colin
NZ

[Steve Bryant]

Silly question time.... Given the amount of oil that would be thrown around by the crank, and rods etc., can anyone tell me why there would be a need for the two 1/8" holes in the big ends of the rods ?  Given that oils and lubrication ability is superior these days, was this something to help with the lubrication of the bores with the oil quality of the day?

Stephen

[Bob Culver]

?? Unlike the holes found in pressure fed engines they are not to lubricate the already over lubricated cyl walls. As above the exact mode of operation is uncertain but oil will enter at some stages and oil and air from the spray vent at other.