jer4251

iTrader: (6)

Ive been told by a few shops that a connecting rod can be reconditioned. I guess its just like boring a cyl wall. but ive got a quick question that i cant seem to answer.

If i have a crank thats in need of oversized bearings for the rod journals, and i have a rod thats been enlarged, how do you determine the bearing size? do they make special bearing for rods with larger journals? im affraid if i just buy a new rod its going to throw the balance off from the rest. Im working with stock components here for a rebuild.

Lets say the crank was worked to .010 under. and the matching rod had to be enlarged a bit to be round again. how would this work?

thanks, sorry if this is a dumb question but i dont have much knowledge of this kind of stuff, but i am learning with all the research ive been doing.

Apeiron

The diameter of the rod is the same after reconditioning.

jer4251

iTrader: (6)

Thanks for the quick reply, But how do they fix the rod without making the hole bigger? I feel better if i understand how it works.

thanks again

Apeiron

All the stress on a rod is along its axis, so the hole enlarges in this direction. To recondition it, the cap-to-rod mating surfaces are shaved down, and then it's bored back out to size.

sofakingdom

iTrader: (1)

What he said...

However, I will add, that it also makes the rod shorter; usually .005 - .010" or so. This increases the (usually) already excessive deck clearance in a rebuilt motor.

I would avoid it if possible; especially, doing just one. As easy as it is to find junk rods that are undamaged, it's usually better to go find a set, than to repair just one.

Note I said "a set"; not, 8 rods. The factory doesn't "balance" motors: rather, they measure rods as they come out of production and sort them into bins sorted by total weight, big end weight, little end weight, etc., all of which vary QUITE a bit; then they machine cranks with their balance set up for each bin; then when a bin fills up, they grab those "matched" rods, and a crank set up to those specs, and assemble them, without ever actually "balancing" anything after the fact. For this reason, if a rod gets trashed, my first preference is always to find a complete FACTORY rotating assy with its 8 origianl rods and original crank, to start a new build with.

jer4251

iTrader: (6)

How terrible would it be if i got a reconditioned crank kit and used one reconditioned rod? this isnt for some high performace race car, just a back and forth to work ride. I'd like to do a full rebuild or 383 stroker with all new parts, but i paid 500 for the car and just want it to run without knocking like it did. I know its not the best idea, but i'd like to just get the correct crank and bearings and give it a go. i have reason to believe the engine had been apart not too long before i got the car. not sure what was done if it was, but the block and cyl walls look really good to me. will one tiny bit of a shorter rod ever be noticed when its all done and running?

Apeiron

Length isn't a problem, it's the potential difference in weight.