Rod Cap Reinstall Alignment

secondChanceFury

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Hello all, I have a 69 Plymouth Fury 3 with a 73 318.

I had the engine pulled out to resolve rear main seal leak and decided to replace the rod and main bearings while in there. After getting everything replaced and measured with plasiti gauge I removed everything one more time. Everything seemed fine. No clearance issues. However, while testing the clearance, I did not rotate the engine.

Now on final install, I lubed everything with engine assembly. I noticed that two of the caps where hard to install. After installing these caps I could not rotate the engine. The caps are actually touching, pinching from the sides.

I thought, maybe I mixed up a cap in the process. Or maybe I have them on backwards? I wanted to at least establish I am putting them in correctly.
The bearings have a tab side and a notched side on both the lower and upper. When installing the cap, should it go tang to tang? or tang to notch?
Unfortunately this is something I didn't notice when pulling them out.

Thank you for your help.

PXL_20240425_124205056.jpg
 
Tang indexes with notch. Did you mark each rod cap before you removed them? Normally, this is done with a number stamp and small hammer. With both numbers (for each rod cap) on the same side, then you know the caps are on the way they came off.

Worst case scenario is that you take the engien to a competent machine shop and let them diagnose the issue and put things right. Probably not what you might desire to hear, but the other alternative would be to have the machine shop operative make a house call. Which might be the least-espensive option when all is said and done.

Just some thoughts,
CBODY67
 
. When installing the cap, should it go tang to tang? or tang to notch?
Tang to tang. The rod numbers are also both on the same side.
Unfortunately this is something I didn't notice when pulling them out.
Were the rods were numbered and did you put them back in the right spot???

I noticed that two of the caps where hard to install.
If there's an issue, you stop before you do any damage. Rod caps should never be hard to install.
 
Regretfully, I did not mark each rod cap. Just put them on the bench in the order they came out.
When I replaced the bearings in each, I took one replaced it and put it back. I was really trying to be careful. Obviously, I should have marked them.
However, I will now go back and make sure at least I have them all tang to tang and see where I am then.
Cheers
 
Regretfully, I did not mark each rod cap. Just put them on the bench in the order they came out.
When I replaced the bearings in each, I took one replaced it and put it back. I was really trying to be careful. Obviously, I should have marked them.
However, I will now go back and make sure at least I have them all tang to tang and see where I am then.
Cheers
They should already be marked. Stamped near the parting line.

If you've mixed them up, that's not good...
 
As Big John mentioned they should be stamped. Both the cap and the rod on the tang side, or facing the pan the oil sqirter v notch faces the pistons on the opposite bank to squirt oil up in the piston.
Would not matter too much if you flipped them (aftermarket rods do not have the v notch). Swapping bores randomly is probably not great because the offset pins would not match and the chamfer of the rod is on not toward cheek, it's toward the other rod.
Some of the stamped numbers may be hard to read, but usually through parts of numbers and the ones you can read clearly it can be sorted out.
 
When replacing rod bearings on an engine that you are not removing the pistons from, you
are better off doing one at a time. It cuts down on the chances of mixing them up. I know
this is no help to you now, but the advice above is good. It should be able to get you back
on track.
 
Why the need to replace the rod bearings in the first place? Excessive wear/clearance, gouging, erosion, bell ended?
 
Hello and good afternoon all.

Thank you very much for the help. As you can see from the picture... well let's just say I found some discrepancies.
My eyes are not as good as they used to be, and most of them were not as obvious as this. Some had a single number stamped across both rod and cap. So that was fun.
However, we got it sorted and now the engine is spinning freely again. I learned a valuable lesson. I will be marking them next time.

This is why forums like this are so important.
Thank you again

PXL_20240425_205248439.jpg
 
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