Headers are inherently warped by a certain amount where they are welded to the separator flange, causing uneven seating against the head. To correct this problem, special thick, soft header gaskets are used to conform to the header and the head to give a good seal. These special gaskets, however, have the tendency to collapse as they absorb heat. This collapsing or compressing of the gasket causes the header bolts to become loose as the collapsing continues for the first few hours after installation.
Determine how you would like to anchor the header bolts. There are several methods. One is to use special locking bolts from a speed shop, which have a special washer placed under the bolt and then a snap ring is placed on the bolt that locks the two together. Another method is to use an inside serrated washer, (a circular washer with teeth like serrations on the inside that tough the bolts and contact the head) under the bolt. This is a good method because the washer's serrations are twisted so that they grip the block as well as the head of the bolt--and they are inexpensive. They can be purchased at any hardware store. The last method is to use Loctite.
Install the first type of special header bolt by sliding the washer on the bolt and run the bolt in and tighten with a wrench. Before they become tight, straighten the washer out so that the flat edge is against the flat edge on the head of the bolt. Install the snap ring on the bolt by pushing it down inside the grooves in the bolt head.
Install the second type with the serrated washer by simply putting the washer on the bolt and tighten. The serrations will not allow the bolt to back out.
Tighten the bolts and drive the car a hundred miles or so before using the Loctite. Once the Loctite is applied, the bolts can no longer be tightened any further without ruining the efficiency of the Loctite. The object is to keep tightening the bolts until the gaskets have collapsed as far as they are going to and then apply the Loctite.
Tighten the bolts at least three times, once every 100 miles, before the final tightening and application of Loctite.
