The_One

Hi folks,
I am rebuilding a 22R at the moment;
If the crank is polished and new rod bearings and pin bushings, pins and pistons are used - do the con rods have to go back in the same order they were removed in?
I found a thread about a guy who was doing a rebuild and forgot to label the con rods who asked a similar question but didn't mention if the crank polishing/new pin bushings, pins etc etc had also been done...

I cant think of any other parts that rely on the con rods going back in the same place they were removed from?

I should mention i did label the con rods in my rebuild, just hoping the machine shop doesn't remove the labels... next time i will use a punch to make little marks on them.

Thanks!

SwVa_1stGen

Yes connecting rods that are being re-used should go back in its original position and orientation
Its more about the set of the rod during its operation, caps always stay with the same rod as well

The_One

Ok thanks. I hope they leave the labels on them!
So it is more about putting the engine stresses on the rods in the same way - so they don't fracture or something?

On another note i ordered a master rebuild kit and asked for .40 oversize pistons, there was no option to also specify oversize rings so i assumed they would send matching pistons and rings...
The kit arrived and the pistons are marked "1.00" which i assume is +1mm which is correct - but the box the rings are in are marked "92 1.5 1.5 4" and I am presuming 92mm is the diameter - however isn't that standard ring size? Are these rings ok for 0.40 oversize?

gsp4life

When I ordered a .040" (1mm) over-sized piston set from 22reperformance, the Hastings rings they sent were definitely for a 93mm bore rather than 92mm std. It would seem to me that if you use them, your ring gap will be much wider than it's supposed to be and it'll blow oil as a result. Go to the machine shop and have them test fit those rings for gap.

gsp4life

In addition to keeping the order of your rods with matching caps, you also want to keep the orientation the same (i.e. which side faces front or back).

It's less important with all new pin bushings, resized big ends and bearings, but still matters according to 22reperformance. I didn't ask why cause I trust them but I imagine it relates to tensile and compressive stresses. Flipping the rod around would create new forces that the metal is subject to, after being heated and cooled for so many cycles over decades in the opposite position.

Disclaimer: I'm not an mechanical engineer or pro engine builder, just a guy who built a strong 22re that hasn't given me any problems. I'm curious to see what other more knowledgeable people have to say about keeping connecting rods in order.

millball

Order shouldn't matter when all attached parts are fitted new, but orientation does. The rods have an oil spray hole which MUST be facing the correct side of the engine block, and the rods caps must be oriented on their rods so that the bearing shell locating tangs are correctly postioned, as well.

gsp4life

And there's millball with the usual dose of common sense: the rods or caps CAN'T be installed backwards if you're paying attention and put it back together correctly.

I just recalled that the machine shop which supplied my bearings got me a set of Federal Mogul rod bearings with oil holes on the wrong side so the hole in the rod was blocked off! Bearings can only go in one way cause of the notches, and according to the light wear marks on the outer bearing shells they'd been test-fitted but the shop didn't notice. Fortunately I did, or my wrist pins would've failed. I ordered a set of DNJ bearings which had 2 holes per bearing and one of them lined up perfectly.

millball

Seems I remember that both the rod caps and the main caps have a sort of point cast into them that should always point toward the front of the engine block.

The_One

Yes that's right, there is a little raised bit cast into them which goes forward.
Is it normal practice to send the rings with the pistons to the machine shop for clearancing or just the pistons? They only asked for the pistons?

millball

If you bought the pistons and rings as part of an over-size set, the rings should need no clearancing work.

You should however, put 1 or 2 different rings into a cylinder after it has been bored (use an upside down piston to square the ring in the cylinder) and check the ring gap with a feeler gauge.

I expect that you will find everything will be just right.

SwVa_1stGen

Order does matter if the rods haven't been refurbished

millball

I'd like to know your basis for saying this.

All rod bearing shells are identical, and all crank journals are as well. How can rod position make any difference??

How can refurbishing rods change whether their position in the block is important, or not??

Of course, all caps must be joined to their correct rods, but rod order in engine must be respected, Why??

SwVa_1stGen

Rods take a set as to how each one is used in the engine some will bend slightly some will twist slightly it isnt enough to be seen quickly but trust me its there, after the set process rods continue to harden under use.
You take a rod from 4 and put it on 1 and it has a slight bend it will put uneven pressure on the rod journals and wristpin which can and will cause premature failure
Theres a reason rebuilders number each rod unless it goes through a refurbishing

Another member touched on it above

gsp4life

Hey now, don't go and use something I said to try to prove millball wrong!

Looking through his posts oughta make it clear that he's done a lot more engine building than I have. I'd consider myself a curious beginner that understands a 22re well enough to give basic build advice. A lot of the conventional wisdom is still beyond me.

The rod order is just something that a guy told me over the phone and he was more worried about me putting them in backwards (which would at least make the oiling hole face the wrong way during crank rotation, among other possible physical material reasons).

millball

Thanks for the kind words,gsp4life, But I am sometimes wrong for sure.

I can certainly understand why rebuilders would conform to factory assembly order whenever possible, if for no other reason than to reduce potential problems to an absolute minimum.

I certainly do it myself when it's possible to do so. I just say that it's often not essential.

The older an engine is, the more important it might be. A splash-lube babbit bearing Chevy from the '40s' for instance, might well self-destruct if its con rods were interchanged..

Most engines made since the 1980s' are very high precision machines made with truly interchangable parts, with many tolerances in the low 10 thousandths. Unless an engine is outrageously abused, engine internals hold these tolerances pretty well. In fact, many modern engines use con rods that are made from sintered metal powder, not forged, or cast from molten metal, as they were in the past.

I run a stable of 3 different Ford escort cars, and I have rebuilt 6 or 8 others, for friends. Those 1.9 and 2.0 single overhead cam engines often self destruct by dropping intake valve seats.
This destroys the head, one or more pistons, and bends, or breaks, those affected con rods. I invariably replace them with used con rods from other junk engines, often with high mileage.

There never has been a problem with any mis-matched con rods, and many of these rebuilds currently have 100,000+ miles on them and are running as well as when new.

I don't do mechanic work for money, but I do strive to use best practices in my work, and I'm not afraid to shuffle used con rods if necessary. I sure would do my best to put them back as original, especially if their used bearings, or pistons and rings are still on them. It is much less important when all new parts are hung on them.

old87yota

This thread has been an interesting read.

One question I have is: what do you mean by refurbished?

I am not arguing. I just have no idea what you mean.

millball

When a con rod is refurbished, a bit is milled from the joining faces of the rod and cap and they then are bolted back together tightly and the rods big end circle is machined back to its factory specs for roundness and diameter. A new small end bushing is installed and precision reamed to size.

Then the rod goes into a fixture and it is measured for parallel and stretch between the big and small end axises. It is either bent to conform or maybe discarded. Sometimes the cores might be magnafluxed before starting. Should conform to all factory specs when finished. Sometimes sets are weighed and material ground off so that each one is the same weight as the others.

SwVa_1stGen

I strated building race engines over 35 years ago so to me there is right and wrong, and no "good enough"