It's Always a Problem: one fastener or the other (now rod bolt):

[Dibbons]

Finally removed the connecting rod caps from the 340 connecting rods after I had a shop install ARP rod bolts and recondition the large end. I noticed right off the bat one nut could not be removed by hand after it had been broken loose with a breaker bar. First tried a different nut but same interference. Brought out the trusty magnifying glass and found on that particular bolt the first two threads are squished. Forutnately, I mistakenly purchaed two sets of small block ARP bolt sets so I can "borrow" one from the complete set and take care of the problem. Unexpected glitch to say the least. Doesn't really show up in the photo, but it's obvious to the naked eye.

 

[R413]

You might take the road and new bolt back to the machine shop and have them do this. Then Recheck the roundness of the big end. ARP bolts are tight fitting and may change the round shape of the rod.

 

[1KoolBee]

Someone likely pounded it out with a hammer. Replace!

 

[Dibbons]

The machine shop cleaned up the jimmied thread for me.

 

[69Bee]

Arp threads are rolled, not cut so an ARP nut would be needed to mate correctly. They probably dinged it or did not use the assy lube required before resizing the rod. Mopar rods only lock for about 0.250" under the head of the bolt, so they are easy to remove. I would replace and the bolts can be purchased in a 2 pack (2 bolts and 2 nuts). Hold the rod in your hand and whak the offending bolt with a hammer and it will come out. Put the new bolt in and whak it with a PLASTIC dead blow to seat the bolt in the rod. Using assy lube, with the cap in place, carefully tighten the bolt by hand to bring the bolt home. Use rags or a towel with the rod in a vise at the big end, NOT the beam, and lightly snug it. The majority of the big end will be in the vise to prevent twisting the rod.

This will simulate a rod vise...

The rod in a rod vise...

 

[dvw]

I wouldn't run a rethreaded rod bolt. Replace it.
Doug

 

[Dibbons]

I wouldn't run a rethreaded rod bolt. Replace it.

I understand what you are saying, but I don't believe it was rethreaded per se, the first 1 1/2 threads had a tiny nick and once the nut is on all the way on, the threads in question are actually outside the nut.

 

[Cranky]

IMO, too many think just because a rod gets new bolts, it needs to be resized. Stick them in and mic it! If it's out of round then resize it. I also install new nuts instead of using any nut that's been torqued. It's the nut that gives up and not the bolt. Went to a seminar some years back that proved it. Now a bolt that's been used under hard use gets replaced at tear down. So far, I've never had a rod bolt failure.

 

[1KoolBee]

Stretch method to tighten. I found a brand new arp bolt in my brand new Eagle rods that was too “stretchy”. In that it exceeded recommended stretch when torqued to recommended torque. I replaced it with another new one. $14 insurance.

 

[dvw]

I understand what you are saying, but I don't believe it was rethreaded per se, the first 1 1/2 threads had a tiny nick and once the nut is on all the way on, the threads in question are actually outside the nut.

Did you replace the nut?
Doug