Cylinder Head Studs
The four-cylinder engines found in TR2-4As seem to fall into two categories: those that motor on endlessly despite being thoroughly worn out, and those that can't seem to shake persistent problems with head gaskets and overheating. With the increasing age of our engines, I think a quick refresher on cylinder head studs and nuts could help solve a lot of mysterious gasket failures and overheating problems.
First, the cylinder head studs. These are of grade-eight spec. and fully capable of handling the 105 ft/lbs. of torque exerted on them when new. By design, every time you torque them, they are being stretched a bit. All metals have a "memory" to return to original shape, to a point. But by the time your engine is thirty years old, the studs, nuts, and washers can be hopelessly tired and replacements should be made. Stretched studs have an hourglass profile when carefully inspected against a straight edge. Stretched studs simply don't have the tensile strength to hold the head down and as a result mysterious head gasket problems can develop. If you suspect that any of your studs are stretched, then all of them should be replaced.
Equally important are the nuts. Factory supplied nuts were approximately 1/2" tall and when new, prove themselves entirely up to the task. With the nuts, you should use only the proper grade-eight flat washers. I've seen everything from spring-washers to nothing at all being used here. Don't assume that what you have on your engine is up to spec., replace them as a matter of course, particularly if there is any indication that there is distortion.
It's often the most obscure things that causes big problems, so I hope this recap can save some of you a headache or two.
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