I decided to "dig in" to these specifically in relation to my 1967, 289. In doing the research, I found that the ones I am addressing here, are also applicable to all 1965-68 260, 289 and 302 V8's that use a 1" carb to manifold spacer.
To many, the carburetor studs and nuts compared here, are "out of sight, out of mind" items. However, some of us don't accept that solution except as a last resort ; thus this comparison.
NutsThe nuts used to attach both the 2v and 4v carburetors to the intake manifold in 1967, are Ford Part Number 351089-S8. As noted above, they were also used on all 1965-68 small block V8's. In addition, they were used beginning in 1957, through at least the mid-seventies, for attaching most, if not all, V8 carburetors to the intake manifolds, as well as some other miscellaneous applications.
The Ford Standard and Utility Parts Catalogs show this as a "Hex Nut", with a 5/16"-24 thread, which requires a 7/16" wrench, is 7/32" thick, and has a zinc plate finish. As a comparison, an ASME "standard hardware" nut with a 5/16"-24 thread, requires a 1/2" wrench, is 17/64" thick, and usually electro-plated (although other finishes are available). An ASME "standard hardware" jam nut of 5/16"-24 thread also requires a 1/2" wrench, but is only 3/16" thick ; these are also commonly electro-plated, but also available in other finishes.
As you can see, the 351089-S8 nuts are not the common "off the shelf" nuts.
I thought that it would be interesting to compare NOS 351089-S8 (first picture) nuts, to those reproductions that are available.
The NOS nuts sampled all measured 7/16" across the flats, and, after measuring at least 8 of them with a digital caliper, all measured
exactly 7/32" thick.
For the Reproductions, I had two different samples ; a set which Scott Drake sells (second picture), and a set that came with the carburetor studs from NPD (third picture)
The Reproductions were of course both 5/16"-24 thread, and require a 7/16" wrench. Interestingly, four samples of each showed that they were all
exactly 27/128" thick..
The fourth and fifth pictures show side by side comparisons.
Bottom line ; will they work ? Absolutely ! How do they appear ? First, being mostly "covered" by the Air Cleaner, they are hard to see, and secondly, I seriously doubt that even the most discerning eye can tell the difference between 7/32" and 27/128".
An interesting "aside" is that in over 55 years of removing these nuts from my own cars, as well as many, many junk yard ones, I cannot remember seeing one in other than a bare steel finish. Difference between Factory and Service Parts ?
StudsThe studs which screw into the intake manifolds for the 1967 289's, are Part Number 88471-S (pictures 6 and 7). As with the nuts, these were used on all small block V8's from 1965 through 1968 with a 1" spacer. This stud appears to have first been used on some 1964 Models, and was still available through at least 1983.
The stud is a 5/16" diameter stud, 2-1/2" overall length, with 1/2" of 5/16"-18 thread on one end, and 5/8" of 5/16"-24 thread on the other end. It is a plain (bare steel) finish.
For comparison here, I used the studs that came with the "Carburetor Attaching Kit" from NPD, and the description of AMK's Reproduction from their website.
The first observation is the finish. The studs from NPD (picture
appear to be a zinc finish ; the ones described on AMK's website are a zinc and wax finish. As only the top of the threads that stick through the nut are "visible", this is not really an issue.
Next, the threads. Both the NPD and AMK studs are 2-1/2" in length, have the correct 1/2" of 5/16"-18 thread on one end, yet on the other end, each have 1-1/2" inch of 5/16"-24 thread, compared to the NOS ones that have only 5/8"(picture 9).
Bottom line ; will they work ? Absolutely ! How do they appear " As noted above, since only the very top of the thread that sticks through the nut is visible, and then not easily with the air cleaner in place, this is not an issue.
An interesting aside here is that, in looking through my Standard and Utility Parts Catalogs (1954, 1959, 1960, 1961, 1965, 66, 69, 75, 81, and 83), there is no 5/16" x 2-1/2" stud shown with 1-1/2" of 5/16"-24 thread. Since AMK and other manufacturers and suppliers, make hardware for other makes besides Ford, there must be some application
that uses a 5/16 x 2-1/2" stud, with 1/2" of 5/16"-18 thread, and 1-1/2" of 5/16"-24 thread ?
SummaryThe carburetor nuts available from NPD and Scott Drake, as well as the carburetor studs available from NPD and AMK, while not 100% "Factory correct", are adequate for use ; mainly because they are not easily seen in a completed project.
However, this comparison only resurfaces "Reproduction issues" that have been around for years, and personally, beginning with 1957-59 Ford reproduction parts which started hitting the market "in force" during the 80's. Specifically, if someone (or company), spends the time, trouble and expense to reproduce a part, why not do it correctly ?
Just to note some Mustang examples, they would include Rocker Moldings that appear correct, but are made with material of almost half the thickness as originals : Safety Convenience System Bezels and lenses that are all red, and Face lettered like only the late 67's and 68's, and even then, the "Belts" lens is incorrectly labeled "Seat" ; the early 1967 Washer Bag brackets being sold the same as 1965-66 ones ; pinned letters and emblems where the pins do not match original holes, just to name a few.
There of course could be many reasons for this, including trying to keep the prices low, to avoid paying Ford Licensing fees, or just plain not knowing. I, for one, would not mind paying 10%, or even 20% more to get an accurate part.
While the examples noted are much more visible than "studs and nuts" subject of this thread, the point is the same.
Sorry, I'll get off the "Soap Box".
Bob
