Replacing Head gasket

[N20LT4Bird]

This is a dicey subject. There were two methods used to apply torque to the head bolts/studs. One method is a stepped torque, where you tighten each bolt in the proper order but with increasing torque in steps. It takes several times through the sequence to get to the final torque. The other method is doing an initial torque, then then tightening per a prescribed angle. This way the bolt may get an initial torque of 22 ft-lb, then tighten an additional 60º. With this method you will need to have a rotational angle meter that slips on the wratchet. My manual calls for stepped torque on 93s but angle for 94 and up. Why? Don't really know but my guess is that the factory had problems with the 93 method. The reason is that no load is being recorded on the fastener. I believe that each bolt or stud is going to have it's own rotational resistance and it's own internal metalurgy that may vary it's clamping force. To merely rotate an addition XX amount of degrees does not account for this. I have seen a fastener torqued to a certain rotational degree, the torque measured, the fastener rotated another 25º and the torque load was unchanged. In my experience in keeping engines together suggests that the most amount of compression of the gasket at equal fastener torque value keeps the gasket from prematurely blowing. by doing the simple angle method, you could have a torque of 70 ft-lb, yet still be able to rotate the faster a certain number of degrees and still have the same torque reading. Even though I have an angle meter, I still went with my own method of torque in steps, but made sure that I couldn't rotate any further without raising the torque value. That angle meter is a bear when you are doing this on the car.

As far as what to do since you already re-used the headbolts? The only thing I would do is after a thousand miles, pull the valve covers and check the torque of the bolts, but do so very carefully. Follow the proper order and use the 93 method to torque and not try to use the angle method. Whatever you do, don't loosen a fastener and then retorque. Then in another 3K miles, pull the valve cover and check them again. As long as they hold, you should be fine. Yes, studs can be used. The only difference between the studs and bolts is how the load is applied to the fastener. Studs are far superior and are a good insurance clause.

Joe, just to piggy back of this for the guys using ARP bolts.......If youre going to be using the ARP head bolts, I would recommend a straight torque setting of about 70 ft/lbs or so (obviously in steps). It tells you in the instructions included in the box of bolts, I cant remember the exact spec of the top of my head. The torque specs follow the bolts, not the car.