Rod Bolt Stretch

[gramps]

What would cause large increase of torque to achieve correct rod bolt stretch,3rd use of bolts and original rods?

[David Redszus]

What would cause large increase of torque to achieve correct rod bolt stretch,3rd use of bolts and original rods?

An increase in friction of the bolt and nut (rod) threads will increase the torque required
for a given bolt stretch.

Check for distorted or damaged threads of rod and bolt.

[mag2555]

Your bolts could have stretched in the thread area which has changed the thread pitch some.
I would not chance reusing them unless you had 100% no choice!

[BillK]

Are you using the same lubricant as originally ? Same torque wrench ? What are you considering a "large" difference ? Have the bolts stretched from their original unstretched length ?

Also how are you actually checking it ??

[bentvalves]

perhaps you torqued them to spec in the past, correct?

and now you are using the stretch method to reach the desired preload and are saying to yourself "wow, that's more torque than I would have imagined" to get the bolt stretched .006"

[strokersix]

Underhead galling perhaps?