I'm currently rebuilding a 76 motorhome 440 to put in my 70 Challenger and am having a problem with rod #4. I have been torqueing all of the rods to spec back to front and turning the engine over in-between to make sure nothing had seized. As soon as I torque rod #4 to spec the engine will no longer turn over. If I torque rod #3 to spec without #4 it turns over fine and if I don't torque the bolts all the way to spec it turns over fine. I checked the bearings and everything seems fine. Does anyone have any ideas about what is causing this and how to fix it?

 

Bullet -

Remove the #4 rod and piston.
Torque the bolts (out of the block) and see if there's free movement on both ends.

Also look for score marks on the cylinder.

Archer

 

If you have no equipment use a piece of plastic gauge and check the bearing clearance

 

Sounds like the rod is out of round... Or the crank might be twisted in that rod journal ?

 

Notch forward? Piston in backward having bearing pinch in the journal radius.

 

Rod cap on backwards?