Years ago I discovered that no matter how meticulous I was about following the torque sequence on the case bolts, the next day several would have slipped below the spec and need to be redone. How could this be?

 

Also on stripping down dozens of gift engines, some case bolts would be finger tight and some would be missing heads. Did the factory not do this correctly in the beginning?

 

The early case bolts were necked down between the head and the threads. So as to stretch a bit more I suppose. All later bolts are a constant diameter head to threads. Super high stress bolts like rod bolts in racing engines do not have a torque spec. They have a stretch spec. Dimples in the bolt head and threaded end are used to set up a special jig to hold a dial indicator in place while the bolt is torqued. You use a breaker bar not a torque wrench. You keep pulling until the indicator says the bolt has stretched .007" for example. And that would be for a fairly short bolt. What hope is there of getting a completely constant torque on all of the case bolts? Remember this is for clean dry threads on a real long bolt. The answer is zero. 

 

So, I chase the threads in the end iron with a new tap. I wire brush the bolt threads even on new bolts. I apply Nickel anti seize compound on the threads and under the bolt heads. I torque the case up in 10 steps.

Then let it sit overnight. Then in sequence, loosen each bolt all the way to get more anti seize under the threads and head and re-torque every bolt in order. You can put paint dots on the right side of each bolt heads today. After the next days re-torque, look where those dots are.

 

Since I am torqueing above the spec of clean and dry, I just pull down to the minimum spec number. Have a few extra bolts standing by as you may loose a few doing this. Note that Racing Beat goes way high on turbo case bolts torque. Download their catalog or find the printed version and buy it. Much data in there.

 

Do not forget a bit of rubber hose in the center of the bolt, or a spiral of silicone to stop the bolt from singing and popping off the head. Used to be so common that a shield of metal covered the bolt heads to keep them out of the flywheel.

 

Loosing the coolant and exhaust gasses in the coolant on a well performing engine, would agree with a cracked iron would it not?

 

Lynn E. Hanover