Great find and spot-on analysis. The only speck of info I might add is that when people tweak connecting rod weights, it is important to tweak each end, i.e. you want all the crank ends to have the same weight and ditto for the rod ends. That is because they don't just go up and down, rather the piston side accelerates back and forth. Perhaps you first tweak piston ends to match, then tweak rod ends so overall weights match. Towards that end, you can buy piston holders that let you weigh each side, some marketed towards hobbyist tuners (Summit, Jegs). Never done so, so just throwing out an issue to investigate.


The piston diameter group spec's have been much discussed here. I thought the consensus was that there was no purposeful intent to make pistons different sizes, the spec just had to do with how the factory sorted pistons and to install any slightly larger ones in cyl #1, because ... (runs cooler or such). Probably applied more to the original manufacturing and doesn't apply much to us today. Regardless, the OP's shop properly honed each cylinder to its piston, so shouldn't matter.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

Take a close look at the forging numbers / general shape of the rod to determine if they are from the same batch or not.

I strongly doubt that a engine maker would take the time to purposely bend a rod to fit a bad bore. Having had a shop for many years / been inside many engines I've never come across one from the factory.

Take a close look at the forging and see if things are bored off center. If the forging was bent prior to machining, it may have continued to bend in use.

I had a 1.6 Ford Kent ( early 70's Pinto motor ) that I was building for a Formula Ford. The rod forging was bowed but the machining was fine. ( RE the forging was bent prior to machining.) In a Pinto it would have gone for years, I didn't use it in the FF build because the rod would be more likely to bend under high load.

If the rod is bent resulting in a shorter length, would this necessarily affect the piston angle ?

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David


1996 Mercedes S124 E300TD - 129k - rolling restoration project -

1998 Mercedes W210 300TD - 118k (assimilated into above vehicle)

It depends on what direction the rod bent.

If the rod bends on the front to back axis, it will be like the rod of the OP with the piston tilted front to back.

If the rod bent left to right , center to center would shorten and the piston would be low in the bore but square.

I cannot see the relationship between length of con rod and angle of piston, shorter con rod lower piston height?

__________________
David


1996 Mercedes S124 E300TD - 129k - rolling restoration project -

1998 Mercedes W210 300TD - 118k (assimilated into above vehicle)

We believe you.

Cheers Frank, glad we are on the same page.

..btw, when you say 'We" who are you talking about ?

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David


1996 Mercedes S124 E300TD - 129k - rolling restoration project -

1998 Mercedes W210 300TD - 118k (assimilated into above vehicle)

It appears that Frank is once again taking issue with my words and again I need to smack him down.

My post 19 is entirely correct, run it by any competent engine builder.

If my words are incorrect, for the benefit of others, please explain why they are incorrect and not just do a vague hit and run..

Is the word "sarcasm", or the phrase "tongue-in-cheek" recognizable by anyone?

No call for that. Save it for over at O.D..

Let's simply impart knowledge and allow readers to choose whose advice they wish to follow.

No brownie points are given for being "right".

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

Many readers come here for knowledge and don't have the background to discern correct from incorrect information. It serves no ones good to let incorrect information stand clouding the issue.

Do you agree or disagree with the information my post 19?

I would like spock505 to weigh in as to what information he deems correct and what he took away from Franks words in posts 21 and 24.

Of course, my mind was fixed on a bend in line with the bearing as this is what i have seen before.

Looking at the OP second photo its clear that the bend is in line with the engine, 90 degrees to the bearing.



SL, these things can blow out of proportion, sometimes better to walk away.

__________________
David


1996 Mercedes S124 E300TD - 129k - rolling restoration project -

1998 Mercedes W210 300TD - 118k (assimilated into above vehicle)

AMEN.

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

So the new rod set came in. All were about 20 grams heavier than the old #1, so I took the #1 from the new set and polished with a flap disk, trying to take the weight equally off of the top and bottom balancing pads.



Ended up within 4 grams of the old one ...





Installed, and moment of truth ... joy.

COOL!

Keep the thread updated as you reassemble the motor. Lots of pictures!

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!