head bolt torque

My first job out of college was developing bolt torquing procedures for jet engines at Pratt & Whitney Aircraft. What I learned from that 6 months of my life is using a torque wrench to tighten bolts is a very in accruate activity.

So regardless of what is in an FSM manual for steps this is what I do;

1. run a tap down all the head bolt holes and use some brake cleaner to clean out any debry and crud.
2. make sure the underside of the bolt heads, both sides of the washers and the surface of the head are smooth and free of burrs.
3. If you have a die run them of the threads on the bolts, if not examine the threads carefully and fill off any dings or burrs. Use the solvent to clean the threads of any crud. The bolts should sping down into the bolt with no resistance.
4. Regardless of what the FSM states always use at least some clean motor oil on the threads, bottom side of the head and on the washers. Definately use the lube provided with bolts like ARP.
5. Regardless of the the FSM. Run all the bolts down finger tight plus a 1/4 turn to seat the head and gasket.
6. Following the FSM recomended toquing pattern the first step should be no more than 25 ft-lbs. Then no more than 10 ft-lb increments to you reach the specified torque.
7. Always go around a couple of times at the specified torque to make sure they are all even.

The most important thing for long life of the head and gasket is even clamping force, this has become critical with aluminum heads on iron blocks to the point that torque to yeild bolts are specified almost universally on new cars now. But for us iron on iron guys removing all sources of friction is appropriate. A simple burr can reduce the clamping force by as much as 40% even though the bolt was torqued to the specified value