Look at this rod cap?

[smaceng]

So in my on-going saga to rebuild my 1275, the plot thickens. While the rockers were all out of alignment, I did find out that the rocker shaft was press fit into the pillow blocks! No wonder they didn't line up. So I checked the bottom end for clearance, and the plastigage said .002 to .0025 for #2 rod and the middle main. No wear on the bearings and the crank is smooth. All STD. All very good! Now I take a closer look and see the horror on rod #4! Why would this be done. Why would the cap be machined like this? Can I get just another cap, or should I get another rod. I am going to balance it. Does any one have an extra? thanks for your help.
Scott

 

[Trevor Jessie]

It is hard to tell from the picture, but I'm guessing it was done to balance the rod.

 

[bgbassplyr]

My guess too.

 

[smaceng]

I've never seen one with this much removed!

 

[bgbassplyr]

Agree with that. Guess I didn't look closley enough, saw a shiny place and assumed. Replace it (the rod and cap) and balance with other 3 rods. Also might want to check the crank journal to see if has been turned. Might be able to to read oversize stamp on rod bearing.

Since you're this far into it, check everything.

Jim

 

[Healeysince59]

That's mutilation. Probably a really bad attempt at balancing.

Marv J

 

[Hairyone]

That's really odd. Is there a dent in the sump & this was machined out to clear it? :banana:

 

[Trevor Jessie]

Yikes!!!!

 

[DrEntropy]

That's WAAAY more radical than balancing would require! Get rid of that thing! New rod/cap and balance all. Sheesh.

I'd be curious as to the reasoning behind takin' that much meat off ONE conn-rod end... other than an insidious sabotage attempt.

 

[smaceng]

thanks for all the input.
Anyone have a single virgin rod and cap they can sell me?
cheers,
Scott

 

[smaceng]

Mystery solved!
After I took the pistons out, I weighed all of the piston/rod assemblies. Ths suspect # assembly was still .4 oz more than the rest even with the big chuck machined out of the cap!
Wouldn't ya know it, the gudgeon pin was the killer! About .065 thicker than the others. At some point in time, the #4 rod was replaced (out of order for stamped number) and my guess it came with its own pin. On to see the machine shop tomorrow and to find another rod.
Cheers!
Scott

 

[DrEntropy]

Whoever did the "balancing" did a really goofy job! Ya balance the rods at the big ends comparin' one against another, NOT as an over-all piston/rod weight!!

wow.

Scary.

 

[Bayless]

That's what happens when some hack gets hold of a motor or most anything else for that matter.