Stripped threads on a piston rod

[1crosscut]

I'm in the process of tearing down a B engine. Have not gotten as far as seeing what the three mains look like yet but have removed all of the pistons.
Babbitt on all of the rods look very nice with shim packs .032 - .035 on both sides of all the rod caps. Unfortunately one of the rods threads are weak and won't hold torque.

Just wondering what others have done in situations like this.

 

[BRENT in 10-uh-C]

Dave, unfortunately at that point it is scrap.

 

[1crosscut]

Realize that. Just curious if folks generally go with 4 new rods or try to weight match a new one to the other three.

 

[johnneilson]

What type of nut are you using?
If a stock style hex with cotter pin slots, it may be the culprit.

I don't use them anymore for a variety of reasons, instead use an aftermarket nut such as
mcmaster #90759A650

Use 55#ft torque

J

 

[Benson]

deleted

 

[1crosscut]

What type of nut are you using?
If a stock style hex with cotter pin slots, it may be the culprit.

I don't use them anymore for a variety of reasons, instead use an aftermarket nut such as
mcmaster #90759A650

Use 55#ft torque

J

It wasn't from over torqueing the nut as it came off buggered up.
I torque rod nuts to #35 lbs.

 

[Jim Brierley]

I use ARP nuts, and 50#, 35 is not enough. Castellated nuts do not have enough full threads.

 

[Dodge]

It happened to me once on a friends car. The babbit was still good so we threaded it to
11mm and used 11mm nuts.

 

[1crosscut]

Is the #35 lbs. listed in the red book incorrect then?

 

[katy]

On page #1-134 and on page 1-143 it says 35 ft lbs, on "Specifications" page 1 it says 40-50 ft lbs.

 

[Y-Blockhead]

Is the #35 lbs. listed in the red book incorrect then?

Yes, the Red Book does have some mistakes and inconsistencies.

 

[Flathead]

Yes it does.