70-72 Judging manual ??'s

[Gary S.]

I am reviewing the 1970-72 TIM & JG and I have come up with a couple of questions that I can't figure out. Any help here folks?

1. Under 9. exhaust system, it states "the nuts on the studs are carbon steel in a self-locking deign." This is for the attachment of the exhaust to the manifold. I have only seen the standard brass nuts and never the original self-locking type. Obviously I know what a self locking nut is, but what did the original look like; is there a suitable replacement, and where?

2. Under Fuel & brake lines it says: "Original brake line nuts at the master cylinder are often stained red and blue to distinguish the different size threads." Is this a translucent, transparent, or opaque stain? Which line is blue and which is red? I have never seen this, even in a 13000 mile car I judged in 2001.

3. I still have the yellow part number stamped on my driveshaft but rust, time, and driving are slowly taking its toll. What is the best way to preserve this in the (unlikely) event that a Bowtie slot becomes available at Hershey this year or Canada in 2004?

Thanks as always for your help.
Gary
72 LT1

[Patrick H.]

Re: 70-72 Judging manual ??'s

Gary,

1. They are commonly called "acorn nuts." Imagine the common acorn-type nuts used for decoration or trim. Now imagine a hole going all the way through. Another way to envision them is a modern self-locking nut with a plastic insert and the insert sticking up a little in the middle of the nut. Now instead of plastic there's a deformed thread doing the locking job. Make sense?

2. Translucent, often on just the thread area. I can't recall which is which. I wouldn't worry about it. I think it is more of an FYI notation.

3. You KNOW my answer for this one. Seriously, after 106,000 miles the stencil on my 71 was still visible and remains so at 126,000 having done nothing to it. I doubt yours is disappearing as fast as you'd think. Again, other than my "usual" answer to you (inside joke) I'd leave it alone. Anything else will look fake.

Patrick

[John H.]

Re: 70-72 Judging manual ??'s

Gary -

Brass nuts were never used by GM in production, although they are popular as replacements as they don't corrode to the studs. Paragon has the original-type "acorn" nuts with the triangular deformed threads - their #6498K.

[Harmon C.]

Re: 70-72 Judging manual ??'s

I had some of the Paragon exhaust nuts and they fit so tight I thought the studs would break out of the manifolds. I also had new studs so they may have been oversize. They also were not shaped the way I though was correct for exhast nuts.

[Dave S.]

Re: 70-72 Judging manual ??'s

Lyle,

I had the exact same problems with the Paragon exhaust nuts. They didn't fit properly and they don't look like originals.

[Patrick H.]

Re: 70-72 Judging manual ??'s

To quote one of my mentors, I'd likely "take the hit" on this one, and use either brass or stainless. Or, I'd use a tap to re-thread them and then use them that way (i.e. without the poor fitting locking feature). Since originals are not easily found, that may be the "best" solution.

Patrick

[Harmon C.]

Re: 70-72 Judging manual ??'s

I did retap them but they don't work much better. The reason I tried to change from brass was that the brass nuts would need to be retightened after driving and to be more correct. If you never drive much it wouldn't be a problem.

[Patrick H.]

Re: 70-72 Judging manual ??'s

Lyle,

Well, it was a good thought.

I've used two brass nuts on each stud before to avoid the loosening thing.

Patrick

[John H.]

Re: 70-72 Judging manual ??'s

Patrick -

That's what I do - I run a 3/8"-16 tap most of the way through them first; the "acorn" portion doesn't look "exactly" like the originals, but I haven't found any others that are closer.

[Gary S.]

Re: 70-72 Judging manual ??'s

Thanks John and others. I have my Paragon catalog open and I see the nuts. The only self locking nuts that I have seen lately have nylon in them. Of course, that won't work for exhaust systems.

Gary