Con rods oil jet holes...

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Fast Eddie

Fast Eddie

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Good, bad or irrelevant ... ??

I can see and argument for them being bad for oil pressure...

I can see how it might be good for a timed 'squirt' of extra oil to cool pistons and lube bores...

But I can also see how the same quantity of oil will exit the big ends as splash anyway, thus negating the benefit...

Any opinions ... ?
 
When i had the bottom end apart last winter replacing a dud camshaft, i stripped the crank to clean the sludge trap. When i removed the rods i noticed the very thin layer of grey coloured metal on the big end shell (not sure what this is, hopefully someone can tell me) had been worn away from around the oil hole exposing the bronze underlying backing metal. I should add that there was no discernible play in the big end and the journal diameter miked up as bang on size.
I replaced the big end shells but swapped them around so the oil hole is covered up. When you think where the hole is situated it is bleeding off high pressure oil right from where it is needed most. There is loads of oil being thrashed around from the crank so no need to worry about cylinder lubrication or piston cooling.
Regards
Peter
 
dobba99 said:
i noticed the very thin layer of grey coloured metal on the big end shell (not sure what this is, hopefully someone can tell me)
Click to expand...

Aren't these type of shells said to be bronze backed lead indium type.

I'm not entirely sure what Indium is, or where/how they obtain it, but thats the grey stuff/alloy....

P.S. Weren't the oil squirt holes dispensed with - once they'd solved the underlying piston design problem that had required them to begin with ?
 
dobba99 said:
When i had the bottom end apart last winter replacing a dud camshaft, i stripped the crank to clean the sludge trap. When i removed the rods i noticed the very thin layer of grey coloured metal on the big end shell (not sure what this is, hopefully someone can tell me) had been worn away from around the oil hole exposing the bronze underlying backing metal. I should add that there was no discernible play in the big end and the journal diameter miked up as bang on size.
I replaced the big end shells but swapped them around so the oil hole is covered up. When you think where the hole is situated it is bleeding off high pressure oil right from where it is needed most. There is loads of oil being thrashed around from the crank so no need to worry about cylinder lubrication or piston cooling.
Regards
Peter
Click to expand...

Not that it will make any difference but the lower bearing shell is the most highly loaded once the engine rpm reaches 4500 rpm or so. That is unless the engine is detonating.

The shock load of detonation will overcome the load from stopping the piston as it nears TDC but normal combustion pressure is considerably less at higher RPMs. Jim
 
If an engine's cooling was marginal, the squirt holes would be beneficial to bathe and cool the pistons, and possibly keep the engine out of the over temp. danger zone. As cooling is not a problem with Nortons, then I'm with Comnoz ..... no particular benefit either way.

Slick
 
If you've ever looked into a sump, the oil sling should keep everything well bathed in oil.
Keeping the oil pressure up for the big end shells benefit would likely win priority ?
 
comnoz said:
I have never seen an advantage one way or the other. Jim
Click to expand...

So ... on my next 850 build; oils holes covered, or allowed to "squirt"oil on piston ??? :shock: ( As the one you recommend, is what I'm gonna do.)
 
Well my performance engines do not have oil holes since I am running Carrillo rods. I also assembled my hot rod 850 with 2 lower shells. My street bike uses shells for a Hyundia so there is no hole.

I used two upper shells in the N15 motor I put together since I had extras.

The majority of the oil flows out the sides of the bearing anyway. I doubt the oil hole has much effect either way.
 
Rohan said:
If you've ever looked into a sump, the oil sling should keep everything well bathed in oil.
Keeping the oil pressure up for the big end shells benefit would likely win priority ?
Click to expand...

This is true, but if cooling IS marginal, then that becomes the priority.

Oil comes off the big ends in a 360 circle, and the lower 180 is shaded from the piston by the journal. When the piston is traveling upward, so is the oil and it will likely impact the piston on the return travel. When the piston is traveling downward, so is the oil, and it will likely be directed away from the piston, so it becomes a matter of degree. If one wishes to intentionally augment cooling, then it makes sense to intentionally direct the oil at the piston. An oil cooler would be a good idea.

If cooling is of no concern, then I would defer that higher oil pressure would be of benefit, but as Nortons with double speed oil pumps and squirt holes do not seem to suffer undue big end wear, it appears to be a non-problem.

Close the holes if one is concerned about oil pressure, leave them open is one is concerned about cooling.

Slick
 
When I rebuilt my '70 many years ago, I thought I was correcting a potentially problematic issue with my rod shells because they didn't have weep holes in the shells, so I replaced them with shells that had the weep holes.... I wondered if someone had changed them on a previous rebuild or if the bike came that way from the factory. The bike still had the original main bearings (1 roller, 1 ball) which I changed out for superblends on both sides, so it didn't make sense that the shells might have been changed, but not the main bearings, which were a known issue.
 
I am going to fit my conrods and shells to the 750 crank tomorrow.

Now you got me thinking..
I now dont know what to do. One question, did all commando conrods have that oil hole, mk3 etc? I cannot remember it on my mk3 build, but that is my memory.

Based upon comments in this topic i should probably keep oil hole intack as it is usually pretty hot here where i ride and you all say its better for cooling.

Cheers
 
Jerry Doe said:
I am going to fit my conrods and shells to the 750 crank tomorrow.

Now you got me thinking..
I now dont know what to do. One question, did all commando conrods have that oil hole, mk3 etc? I cannot remember it on my mk3 build, but that is my memory.

Based upon comments in this topic i should probably keep oil hole intack as it is usually pretty hot here where i ride and you all say its better for cooling.

Cheers
Click to expand...

Yes, they all had the holes.
I would probably just fit them in the normal position.
I have never been able to tell if they made any difference in the heat or longevity of the engine, but then I don't think they will hurt anything either. Jim
 
Thanks Jim for the advice. I will fit them as standard then. I am looking forward to getting the motor built.
 
FWIW Small block Ford 221-302 family used to have squirters on the 221 and 260. Done away with on the 289.
 
When i removed the rods i noticed the very thin layer of grey coloured metal on the big end shell (not sure what this is, hopefully someone can tell me) had been worn away from around the oil hole exposing the bronze underlying backing metal.
Click to expand...

On a Vandervell VP2 bearing this plating is lead/indium, it serves to protect the copper/lead from acids in the oil, gives the harder copper/lead some embeddability (allows crud to be absorbed into the bearing) and the Indium acts as an anti seize agent and is only needed during running in. Other copper/lead bearings use different plating and can have a further layer below to help them stick ie a nickel plate, there are lead tin copper overlays and lead tin overlays and even silver which is the closest in anti seize to indium and used by Ferrari.
 
Dread to think what materials some shells available these days are using..... Luckily some of us planned for the future and collected all the Vandervell shells we could while they were still available, especially the 40 thou under ones!!
I assume you all know that between AE and Vandervell shells there was a 0.0005 inch difference that can result in one manufacturers shells giving a different feel to rod movement after you have bunged the rods on the crank........ The Company myself and a friend used to grind our cranks insisted upon being supplied with the rods and shells to be used so they could grind the cranks correctly. I dont suppose such things happen these days.
Wonder how accurate on size the shells available these days are?
 
Modern shell bearings for automotive applications have closer tolerances now than 20 years ago, this is due to first the Japanese and then US and European Auto companies going for Graded cranks and bearings. The tolerance bands are typically 5 microns and were reducing to 3 microns, when you combine the graded crank to the graded bearing you get a very tight hold on the bearing clearance achieved on an engine, the Japanese who developed this say it reduces engine vibration. This tightening of tolerances only applies to first fit, the aftermarket does not bother with graded bearings or cranks and on these engines the mileages they can achieve means you don't bother rebuilding anyway. So sounding off about today's production being inferior is just that, sounding off.
 
Todays production methods, when they can be used, are far superior - it is the bane of my life every day, sadly made worse by the large skills gap this country has in engineering. Some companies do not even know how to use old tooling of the bad old days, employees that did have mostly retired!!

One part that I have made was removed from the bed, set up by hand for the next process and bored - I had no problems. Now it is rotated on an axis by the new Haas and it has highlighted some major problems with the mating parts.

Modern big end shells - nigh on fit and forget, and those of you who have fitted a modern set in the last 10 years will no doubt find when you next strip your engine that they are worn but not worn out.

As for oil jet holes, either or with this one, in 500 twin would not be bothered - maybe even a good idea to keep oil pressure up, in an 850 or tuned engine I would have them on the basis that the high capacity pump can deliver a large amount of oil, I would want that quality oil in every nook and cranny of my engine, not so much for lubrication but for heat removal.
 
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