I believe Ol'Henry put stops on the manifold bolts for the good reason of protecting the block from over tighten the manifold studs into the casting as your wrenching the manifolds on tightly. I would think that people would pay the extra $$ to use these rather then a plain stud you could over torque into the block. I welcome your comments.
Ol' Henry or some of his buddies that had a drop forge said, 'Bottoming out can cause a snap off, or worse yet crack a casting! If we put a mild shoulder here, folks will know to slow down and the stud will soft seat!"
Then rolled threads came along, and someone decided that most of the benefit of rolling a thread was lost if they also had to roll/head up a reasonable stop. It added an extra step to the process.
A bright young MBA stood up and said, "Don't worry about the shoulder, when they run out of thread it is visual enough and if they are too stupid to keep on speed-wrenching...well our parts service revenues go up"
All at the meeting approved...and the young MBA kept finding similar opportunities until he was eventually promoted to CEO...but by then, he had no fat on the bone to work with and had convinced his own people that people didn't have to think and that people were more of a liability than an asset! And thus, began the wholesale decline of the American manufacturing engine, because they kept outsourcing the work to places where quality rejects caused the supply line to choke.
They then sent a 25 y/o supervisor south of the border since they had early retired all of the white-hairs, to teach folks what to do, folks who were now willing to strike over a quality reject where a CAD drawing only knows to call out a 1/16x45 chamfer on a journal end and the operators of those manual tools said, "Are you kidding me? That's break sharp corners and I use a file! Close enough, ya' know?...you reject my work and we'll see how far up this file fits!"
And so like the tale of the LORAX, Dr. Suess was correct once again and tried to have us teach our kids otherwise
I'm afraid you are going to have to search for those. They are around, and there are two lengths of them too. I think the longer one is for the valve covers, or possibly the early style manifold clamps, and yours too if they are turned over. I think they went to bolts in '26-7. Gosh can you imagine trying to line up that manifold without studs? Anyhow Jay, I'll bet you found them at the Auburn meet? Clean em up an use them!
That's great George
George, they were taking cost out of the product so Henry could drop the price. In theory it was a good plan. But without Failure Mode Effects Analysis, documented processes and process controls, sufficient design testing and preproduction evaluation, though the cost of manufacture was lowered and the cost of the vehicles went down they shot themselves in the foot through the improper processes of Engineering Change Control. And then in order to create the type wages organized labor demanded they made product without the controls to satisfy the greed and ended up building cheap low quality product and sold it at inflated prices to fill their pockets and the pockets of organized labor. Then they ended up shutting down once great manufacturing centers like Detroit because somebody thought they could save a buck in the end instead of spending it up front.
When were those used? I'm assuming not through end of production in 1927. There would be a lot more of them around if they had been.
My 1926 has them.
Speaking from my piece of the industry, common sense is prevailing. There was a DIN standard written which was eventually embraced by the industry worldwide and it became ISO 13715.
ISO 13715 invoked on a drawing tells them the maximum chamfer or fillet allowed on a part. This means it can be machined or filed down as you mention in order to meet the specification. In cases where the object of the game is to knock off the flash and it doesn't matter if there is a radius or a chamfer, then callouts such as these are employed. A positive number indicates extra material, a negative indicates a permissible corner break or metal removed.
It guarantees a functional part and makes inspection of a minor feature a lot easier.
In regards to the manifold studs, I agree it would be better to have a shoulder. Most designs that I see now do not have straight studs; most have a hex washer head or another feature to ensure correct insertion depth.
Thanks for that update...it sure makes sense for what 'break sharp corner' really means in terms of a max. While I was being a bit cute with my story, the facts of the example were true.
I know a company in Mexico that made $150,000 bucks worth of turned shafts for a company in Baltimore...only to find them all rejected on receipt because the QC manager had made a gauge that was a go-no-go for that 1/16x45 call out with a title block tolerance zone of +/-0.010"! There was no appeal possible, and yes it was really a 'break sharp corners' issue.
Without referring to my 1925 parts list or the Service Bulletins, I believe those "collared" studs & clamps, as Jay pictured, came into effect when Ford offered the combination mixture & choke assembly to convert earlier models. A different designed hot air pipe was also used specifically for the combination set up - it no longer had the riveted "ear" to attach to the # 4 stud but a portion of the tin was stamped out to form it's own attachment point. That stud was used through the end of production.
Departing from the thread drift on mfg.......
According to Bruce's CD Encyl.
The parts books indicate changes to the clamp (3065) and the stud (3066).
The short stud (3066C) with flange was introduced late, for the change to the 'recessed' style ('24-'27) clamp sometime in 1924.
Short version 2 5/8" long stud on recessed clamp, shown. The clamp 'recesses' under the manifold.
(As noted for some reason two lengths of the 3066C can be found, most are 2 5/8", the other is 3".)
Below is the pre-24 clamp with the 'web pads' and it uses the std. long length 3 1/4" straight stud with no flange. This stud is now is made by the vendors, without flange, and fits both styles of clamps.
Pre- '24 clamp with long straight 3 1/4" stud.
Photo shows how the 'Recessed' style clamp, '24-'27 can be used with the earlier long 3 1/4" stud, by just swapping it backward so that the recess is now outboard.
Reversing those later manifold clamps looks tacky.
Thanks Dan for taking the time to show us the differences in the manifold studs. This takes a while to put This information and Photos together.
Just to be clear, the clamps in the last photo are actually upside down for the later cars.
I had a lot of new ones on my $1.00 table at Chickasha I think they were to high!!! get them next year!!!!!!!!!!!!!charley
If you tighten too much, you will strip the threads whether it has the ridge or if it bottoms out. But the ridge would keep it from pushing a hole through the bottom into the water jacket. The stud doesn't need to be force tightened into the block. just screw in as far as you can by hand or with pliars and do the torque of the manifold with the outer nuts.
If you want them I will make them after the sale, let me know, Bob
Those are the T parts you'll find in boxes of junk off a farm. Been there and done that a few times!
That is the kind of stuff that makes this hobby so interesting. I built a '25 pickup a few years back out of parts, and I had to research all that stuff, and yes, it has those manifold studs.
To answer your question I have 2 answers: 1, it's cheaper and 2, no one's complained about it.
Whether you strip the threads by bottoming and pushing the threads out or pull them out because of a shoulder doesn't make any difference.
If you yank on 'em with a 16" extension they're going to strip either way.