Gudgeon-Bushes and Oil-Feed, and Are These Bolts New ?

[rfs1957]

Two parts to this one.

1. Bushes and Oil-Feed :

I had my con-rods honed / re-bushed / checked / balanced etc by a Well-Known-Refurbisher.

I had understood that the oil-feed drillings up the centre of the con-rods were meant to feed the gudgeon-pins via the holes in the gudgeon-pin bushes, with sideways encouragement in the form of the spider-finger reliefs.



I'm therefore puzzled by what I've been sent, see above.

With the bushes positioned thus, there is obviously no longer any pressure feed to the gudgeon pins.

I've subsequently been advised elsewhere that this is nothing more nor less than a Complete-Cock-Up, but before I drag out the guillotine and add this to the lengthening list of incompetence and gouging that I've experienced in the hands of the Well-Known-Refurbisher, I'd appreciate any informed comments from others with relevant experience.

I'm so staggered by what I think I'm looking at that I need some encouragement to believe that it's really as bad as I think.

2. Have I got £120 plus VAT worth of New Bolts and Nuts here ?

My con-rods were returned "assembled" with caps and what I had presumed were the new big-end nuts and bolts I'd seen on the invoice.

Upon dismantling them I'm wondering if they're not actually the old ones ?



The fretting on the shanks and the various marks on the heads mean they don't actually look like new parts at all.



Anyone had new ones recently and that could confirm my suspicions ?



There were even a couple of shavings of swarf (like vestiges of thread crowns) that came off the pile of nuts and bolts as I had them in the cleaning bath ...........

[steve3.8]

Rory ,
I don't think they have done wrong ,although not oil pressure fed as per original i would guess they have fitted the bushes as they are to mimic the later S3 XJ6 wide blade rods , done to reduce oil consumption . The later rods without the centre drilling relied on splash lubrication only.

One thing to check for is how true and square the honing is , thread 3 conrods onto 1 gudgeon pin and see how parallel they are together , you don't need a tilted piston flying up and down your clean new cylinder bores !.

S3 [left] and centre drilled conrods .

[abowie]

1. Looks wrong to me.

2. I recently received a set of "new" con rod bolts from one of the usuals. They were clearly used, with damage to threads, oil staining and flattened knurling. They looked identical to yours. Although I eventually got a refund the seller essentially denied all knowledge and tried to blame me for mixing up the bolts with old ones. So it's possible that your refurbisher got the same ones I did.

[rfs1957]

Thanks lads.
My suspicion is that as rods with no centre drilling are a lot cheaper to make, they were indeed cheapened and then trumpeted by Jaguar as an improvement to reduce oil consumption.
So I quite like the idea of a pressure feed to the top.
A frequently-mentioned (on this Forum) engine specialist was quite adamant that blanking off the feed was simply not how 3.8's were meant to be put together, even today.
Anyone else got five bob's worth to throw in ?

[PeterCrespin]

Thanks lads.
My suspicion is that as rods with no centre drilling are a lot cheaper to make, they were indeed cheapened and then trumpeted by Jaguar as an improvement to reduce oil consumption.

So I quite like the idea of a pressure feed to the top.
A frequently-mentioned (on this Forum) engine specialist was quite adamant that blanking off the feed was simply not how 3.8's were meant to be put together, even today.
Anyone else got five bob's worth to throw in ?

Your rods are fine - not even a hint of cock-up. The small end splash feed is universal these days, give or take a Pluto. Most don't even bother with the cross groove but do have a countersink on the external side of the hole, just as piston bosses do on the underside. The small end wears hardly at all because it moves hardly at all, relative to the pin, especially in a long rod design. The pin is fully-floating when warm, hence the circlips. In use the pin moves in the piston as well as in the bush, so on average the movement between pin and bush is half the total angle subtended between the rod and cylinder axis at 90-270 degrees crankpin rotation. i.e., insignificant compared to normal rotating shaft wear, when a positive feed would be helpful.

The bolts are a press-fit on high-precision ground shanks and under-head knurling. Even brand new ones should show markings if subsequently dismantled. Presumably any swarf would be hidden in the bolt bore where it was gouged out. It would only be revealed / made 'available' to do damage, once the interference area of the bolt bore was opened up on dismantling. Can't say I've ever seen this though...

The bolts should also show markings from assembly and disassembly, depending how the head or tail was pressed or tapped in/out. The coated new nut faces should show markings too from full torque for checking the big end eye for ovality, as those do. You have new style bolts in old rods, so if your S1 rods were fitted with standard drilled/castellated fasteners, they have been upgraded.

The drilling along the rod beam is old school and probably diesel engine/slow-rev related, where added mass is less of an issue. I put it in the same league as the heavy old clamped gudgeon pins, that only rotate in the piston bosses where splash from way down in the crankcase might not sufficiently lube a bush high up a long narrow bore. High speed IC engines don't need the drilling.

With your fabrication/engineering skills Rory, I'm mildly suprised you farmed the job out. An adjustable 1" hand reamer does the trick just fine.

[rfs1957]

Asking other peoples' opinions does not always mean that one doesn't have a clue oneself.

Modern engine practice has of course left this pressure-fed feature behind, but I like it, and I suppose I would like to have been consulted !

The Jag rods do not have any encouraging dimple or countersink on the tip that one tends to find on modern engines.

The "trade" contacts I've had are spilt about 50/50, pretty polarised.

I only got involved with confiding this kind of work to a third-party in the context of having all sorts of machining done for which I'm not equipped (relining the block ? replacing the tappet guides ? changing 12 seats ? grinding the crank ?) and was happy to pay to have the rods aligned and straightened, balanced, big-ends resized, pin bushes changed and honed etc by a firm that does that day-in and day-out.

Especially as I find using a big reamer over a relatively short length of bush very difficult to stop chattering.

However once you start to find things that have been botched or damaged you start to ask questions about all the rest.

[steve3.8]

It's not modern practice Rory to rely on little end splash oil feed , for instance the lotus Twincam for one and many others have a very small hole in the shoulder of the conrod at the big end , every rotation when the holes in the crank and shell align it sends a squirt of oil up to the little end , Jaguar must have assessed that the rotating mass was enough to lubricate , and it is removing 6x small oil pressure losses.

Ford essex 3l ,


The S3 xj6 conrod sets i have came from 50-70k mile engines that i stripped , they shown minimal wear and were still within tolerance.
I understand your hesitance without the oil feed but it is proven .


Did the engine specialist say why the conrod drilling was necessary to the 3.8 and not the last 4.2 as Jaguar built ? .

[Geoff Green]

These are my new ARP rod bolts.
If I were a race engine builder I would have many race tested parts that would have road life. However I would not sell these race tested parts as new.

[PeterCrespin]

Fair comments from all, especially if the job was part of a bigger tranche of machine shop work. I’ve done more bike engines than cars, but only recall one oil feed rod. Certainly never seen it on Carillo or Arrow cutting-edge H beam rods. Admittedly quite a few engines, two-stroke or four were not shell bearing type.

AFAIK the rod shoulder oil jet is usually to lube the rear thrust face of the piston, especially oversquare short skirt types that tend to rock in the bore more? There’s also oil-cooling of the piston crown from beneath but isn’t that also a different jet arrangement ?

Rory, I’ve got an uncracked odd filler-side cover. Are you sure the polisher didn’t do something stupid? Not that you’d expect polishing heat to warp that badly, but maybe leaving it undernatch a ton of breeze blocks?...

[rfs1957]

It's OK Pete, there were two cracked holes on yours but in exchange for yours becoming the banana they gave me this good un-cracked one that just needs a bit of polishing.





And to answer your question, welding and polishing were done by the same firm.

Now, which polisher can I trust with all five bits ?

Only the exhaust cover really needs doing, but it would be nice to freshen up the other four parts and get a uniform polish across them all. The nooks and crannies have had a very quick nuzzle from a distance on the bead-blaster and will come up really easily ............









Any proven UK addresses much appreciated.

[PeterCrespin]

It's OK Pete, there were two cracked holes on yours but in exchange for yours becoming the banana they gave me this good un-cracked one that just needs a bit of polishing.

Embarrassing though Rory. Must’ve been the only one at the time without twin D-Type breathers welded on. I remember sending it or them to the bike guy in Connecticut, but hope I didn’t ask top dollar!!