[Tim Ayers]

Originally Posted by Pete

Almost everyone understands the basic problem as stated.

The fix should be done BEFORE any other machine work is done on the block.

The cause:
The stud is bent. Not likely with new studs.

The thread in the block is not straight due to rust and corrosion or bad previous fix.
A tap run in by hand will NOT necessarily correct this. The tap needs to be run in on a machine like a mill, head/block machine or a fixture that bolts to the deck to keep the tap vertical.

The old myth about using the correct class of tap in this case is over kill. The threads have seen so much use that they are way beyond the tap tolerance to start with. An ordinary class 2 tap is adequate. If you can screw an oil lubed stud in with your fingers and it has a slight drag, the thread is tight enough.

Putting a nut on the end of the stud and bumping it with a hammer or using the pipe method will work most of the time but there is a better method that is non violent and will also check the condition of the stud and the block thread before any assembly work has been done.
You need a piece of 2 inch round alloy bar stock (SAE 4340) with a 7/16 hole through the middle and
FACED SQUARE ON BOTH ENDS. The length will be the same as the thickness of the heads you are using. You will need a HARD high nut also. After you tap the hole, oil the stud and screw it in the hole to be tested. Screw it in by HAND till it bottoms and BACK IT OUT 1/2 turn. Put the sleeve on the stud and the high nut and torque to 10 ft. Lbs. ABOVE the torque you will be using at final assembly.
If it holds and feels good when tightening, back it off and remove the sleeve. Now take a square and see if the stud is square with the deck. It should be. If not you have 2 choices. One, fix the thread in the block or, two, Mickey Mouse the stud with a pipe or hammer.

In any case you know what you have BEFORE final assembly. No rust or dirt in the cylinders or ports.

Great suggestion