The torque idea is based on how much drag is generated between the rolled threads on the bolt and the cut

threads in the hole. So, clean and dry for both sets of threads give the highest torque reading per unit of bolt tension. One of those "Round-A-bout" methods of recovering data.

 

If the threads are all uniform and the gizmo that torques them up was calibrated this morning, and the clutch on the one that does number 9 has not run out of lubrication again and is torqueing number into the stratosphere.

 

In any case we count on a completely dry hole and bolt to predict an important outcome.

 

Case bolts are not torqued into their elastic range. This may have been the case with the reduced diameter

early bolts, but the full diameter bolts would probably deform some pieces. The thick bolts produce a more uniform torque because they are stiffer in torsion. A truly dry hole with the early bolts produce a stall and then a breakaway with a squeak. Then the torque is lost and the bolt must be turned further and so-on.

 

So, I just put anti seize on the threads and both sides of the washers. This is what Racing Beat says to do.

 

This added tension makes the stack stiffer in bending and torsion. It helps rotor housing deformation during detonation. This is where the loaded surface of the housing turns black from scrubbing on the irons.

 

In high output engines the spark plug side gets every hole oversized and dowels added. All of the case bolts outside the doweled area are over sized for added torsional stiffness.

 

So, replacing a thin bolt with a thick bolt would produce a slightly higher tension, but not enough to matter, so long as the bolt was dry and the hole is dry.

 

If the rear of the engine is available, I would retorque the whole stack. Mark the bolt heads and the iron with a dot from a Sharpie and be amazed by how many bolts pull down further.

 

One at a time in the proper order: turn the bolt backwards one full revolution with a breaker bar not the torque wrench. Then with a calibrated clicker style torque tighten the bolt in one continuous motion until the wrench clicks the first time.  

 

Do the whole sequence a second time. Not the loosen part, just check the torque again. Several may move a bit more.

 

Torqueing a new build is different than an assembled and run engine.

 

Download the free Racing Beat manual and catalogue. Then read it..........

 

Lynn E. Hanover