Model A Ford - testing engine block threads

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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.

Опубликовано:

30 сен 2024

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Комментарии : 13

@allareasindex7984 2 года назад

I love understanding the technical details and you explain things in plain language without jargon. Thank you!

@mikeb7837 2 года назад

Enjoyed the video. I can see where to is better to do this test and not have the threads pull out when you are torquing the last nut with the head on. A question that occurred to is: what are your thoughts on reusing lug nuts?

@alexiskai 2 года назад

I assume you mean wheel lug nuts. These are fine to re-use as long as the threads are good. There's much less force on them than on the head nuts. The most common failure with wheel lugs is for the studs to come loose from the hub.

@dougsather2939 4 месяца назад

Very nice video, I have a Brumfield head and I will surely follow your procedure before I put it on. Thank You oh I have a 1930 Coupe B45

@jasonsuggs111 3 года назад

Thank you, this is very informative

@robdoe2420 Год назад

Nice, keep them coming, please.

@alexiskai Год назад

Got one in the editing bay now.

@Cougracer67 3 года назад

It's easy to compensate for oversized washer holes: Just go a size smaller, and also note the difference between SAE and USS sizes. In some cases a metric washer will give the snug fit.

@alexiskai 3 года назад

Good suggestion. Washers can still throw off the clamp load, and they don't spread the clamp load like the spacer does. But I agree that, if you insist on going with washers, having a snug fit is critical.

@michaelburns3645 3 года назад

@@alexiskai Why are you torquing the nuts to 65 when the original Ford specs call for 55 ft lbs ? According to Snydars they recommend 55 ft lbs max with their 5.5 head .

@alexiskai 3 года назад

@@michaelburns3645 That's a great question and something I should have covered more fully in the video. Several reasons: 1. It's a common misconception that the original specs call for 55 ft-lbs. I've never seen anyone produce these specs. Modern torque wrenches were not used on the factory line. Workers torqued by feel, and it's likely that if anything they applied more torque than was strictly needed. 2. 65 ft-lbs is recommended by some head makers, notably by Larry Brumfield for his Super Brumfield heads - and since this is Larry's procedure, I went with his standard. 3. People sometimes opt for 65 ft-lbs if the block or head (or both) has some low spots, on the theory that it will cause the iron to accommodate a little more and close those gaps. 4. There is a common idea that 65 ft-lbs is Crazy and Way Too Much and will lead to thread failure. The truth is that most heads will handle 65 just fine, even with Class 2A threads as you see on these general-purpose studs. So it's worth showing people in the video that a head with what I consider normal wear is actually pretty strong. 5. There's evidence that torquing a fastener to a higher percentage of its proof load is actually more stable, over a long period of cyclical tension load, than torquing to a lower percentage, so if the block can take 65 ft-lbs then that may be a better setting. This is covered on p. 59 here: practicalmaintenance.net/wp-content/uploads/Fundamentals-of-Threaded-Fasteners.pdf Having said all that, as Larry notes in the written description above, if you plan on torquing to 55 for your head, you could reasonably torque to 55 for the test as well. I'll be doing 55 for my new cylinder head. If 65 gives you the willies, don't do it! Better to test at a lower load than not to test at all.

@831BeachBum Год назад

You should always zero out torque wrench back to zero after using if you're not going to use it for a while. Also, you shouldn't use a torque wrench to loosen a bolt or nut. Just saying.

@alexiskai Год назад

That’s good advice for anyone!