Model A Ford - testing engine block threads

In this video, I'll show one way to test the integrity of the threads on your Model A engine block stud holes. This is a good test to run if you:
are having head gasket problems
have the head off for the first time in many years
had problems removing any of the studs
know that any of the stud holes have Helicoils or other insert repairs

Required parts/tools:
torque wrench
11/16" socket
30-weight oil and a brush
set of Grade 8 Model A head nuts
at least 7 Auveco 9712 studs
steel spacer (specs in the video)

This test was designed by Larry Brumfield. Larry designed high compression heads for the Model A and sold thousands of them in the '80s and '90s.

I have a note from Larry that he asked me to add after viewing this video:
A stud hole test can be equally important for testing at 55 pounds for stock head installations on questionable blocks. If the holes pass the test then testing at 65 is not necessary and could possibly cause a hole to fail that would have not failed at 55.

Please explain to the audience in these simple terms that a nut loses a certain amount of their clamping power each time they are reused as the thread angle and pitch are affected by the load and friction, i.e., a deformation takes place. This increased friction between the deformed threads causes the applied force with the torque wrench to not be equal to the actual force or clamp provided by the nut as it follows the inclined plane. In other words, the clamp is less and becomes progressively less each time the nut is reused even though the torque wrench is still set at the same value. That is important to consider if one wants an accurate stud hole test as well as the best clamp and even clamp from nut to nut when installing a cylinder head.

An even harder grade of stainless steel could be obtained if one wants to specify the grade. The piece you found at the scrap place served the purpose but it was the most common grade, i.e., type 304, 18/8 stainless.

One last thought.  It’s not good practice to use an accurate torque wrench to loosen tight nuts or bolts. Use a regular wrench instead for loosening purposes. Use the torque wrench for tightening only!

Update: Jan 18 2022 - Larry Brumfield passed away earlier this month in Waco, TX, at the age of 65.