57-58 Corvette w/4BC AIR CLEANER STUDS

[David L.]

According to the 1958 Chevrolet Parts Catalog the air cleaner stud for a 57-58 Corvette with 4BC is GM # 3750992 and is described as 1/4-20-20 X 3 3/8. A few decades ago I bought a box of 30 or maybe 40 air cleaner studs at a swap meet. Recently in these isolated times I have been trying to determine the applications of these air cleaner studs.
In the photo below are what I believe to be 3750992 air cleaner studs as they measure 1/4"-20-20 X 3 3/8" (top T.L. measures 15/16" and the bottom T.L. measures 9/16" on two of them and 1/2" on the other).

According to Chevrolet Parts History GM # 3750992 was discontinued in March of 1961 and replaced with GM # 3785255 (1/4"-20-20 X 5") which had to be cut down to prevent damage to the hood.

I have many assembly manuals but I do not have a 57 or 58 Corvette Assembly Manual.

I have researched the Web without much success. The reproduction air cleaner studs for 57 & 58 Corvettes seem to vary from Corvette vendor to Corvette vendor.

Dave

[Bill B.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

I have a 58 AIM and I thumbed thru the pages looking for any air cleaner (FI, 2x4,1x4) illustrations which specifically showed "stud" with a part number. Following is what I found for you:

2x4 Application-Stud part number is 378921. Drawing date is June 26, 1958 and Revision note indicated released for 59 on August 15, 1958. Additionally, on August 18, 1958 Revision Record note indicates the stud was previously part number 1558773.

Fuel Injection-Stud part number is 3750005. Drawing dated June 26, 1957. Revision Record shows "Redrawn & Revised" on August 16, 1957.

1x4-Stud part number is 3718921. Drawing dated June 12, 1957. Revision Record shows "Redrawn" on May 15, 1958.

Looks to me that at least in 1958 both single and dual quad carbs apparently used the same "921" in late production and most likely this would have carried into 59 production. And, I assume the "921" was used in early 2x4 applications but early 1x4 started out using "773" until it was changed to "921". None of this information appears to be consistent with your above GM info?

[David L.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

I have a 58 AIM and I thumbed thru the pages looking for any air cleaner (FI, 2x4,1x4) illustrations which specifically showed "stud" with a part number. Following is what I found for you:

2x4 Application-Stud part number is 378921. Drawing date is June 26, 1958 and Revision note indicated released for 59 on August 15, 1958. Additionally, on August 18, 1958 Revision Record note indicates the stud was previously part number 1558773.

Fuel Injection-Stud part number is 3750005. Drawing dated June 26, 1957. Revision Record shows "Redrawn & Revised" on August 16, 1957.

1x4-Stud part number is 3718921. Drawing dated June 12, 1957. Revision Record shows "Redrawn" on May 15, 1958.

Looks to me that at least in 1958 both single and dual quad carbs apparently used the same "921" in late production and most likely this would have carried into 59 production. And, I assume the "921" was used in early 2x4 applications but early 1x4 started out using "773" until it was changed to "921". None of this information appears to be consistent with your above GM info?

Bill,

Thanks for responding. I guess that the 3750992 stud listed in the March 1958 Chevrolet parts catalog is a service part and not necessarily an assembly line part. Apparently GM # 3718921, 3750005, or 1558773 were not sold over the counter in March 1957, March 1958, February 1961, or October 1962. My 1963 Chevrolet parts Catalog (Oct. 1962) lists stud # 3785256 (1/4"-20-20 X 9") for ALL models with a note to cut to required length.

Another Example: My 1963 Chevrolet Parts Catalog (Oct. 1962) lists GM # 3825532 (1/4"-20-20 X 3 5/8") as the air cleaner stud for the 1963 Corvette while the 1963 Corvette Assembly Manual lists the air cleaner stud as 3777266 which apparently is 1/4"-20-20 X 3 1/4" in size. It was not until Feb. 1967 that GM # 3825532 was replaced with GM # 3777266 as per Chevrolet Parts History. At this point in time I have no clue what other models were issued the 3825532 stud except for possibly a Chevrolet truck.
Back to researching.

Dave

[Richard M.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

Dave, to add to Bill's research....

The 1957 AIM pdf can be downloaded from Russ Uzes site..... http://www.earlycorvettes.com/
Scroll down the page a bit to the link to download.

I just checked for the studs.

1x4 stud is 3718921 (page 85 of the AIM pdf, Sec 6 Sheet 3.00)
I did a search using gmpartswiki and for some unknown reason it only shows that part used for the Corvair.

http://www.gmpartswiki.com/getpage?pageid=3809

2x4 stud is 3728798 (page 188 of the AIM pdf, RPO 469 Sheet 1.00)
I found no entry for this. I'd imagine not available in service.

Rich

[Bill B.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

I have always been surprised how accurate the AIM drawings are. But, while going thru the pages I noticed a wiring harness illustration which showed the motor with a single carb and an air cleaner...so I visually scanned over it looking for any stud info. There wasn't any but I then noticed that the air cleaner was nothing like the low profile Corvette air cleaners but akin to an air cleaner you would see on the Tri-Five passenger cars. Obviously this particular page was not very accurate! Doesn't help you but I found it novel.

[David L.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

Rich,
Thanks for the information. I will print out the manual and add it to my library in the basement once I straighten out the mess.
Dave

[David L.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

Dave, to add to Bill's research....

The 1957 AIM pdf can be downloaded from Russ Uzes site..... http://www.earlycorvettes.com/
Scroll down the page a bit to the link to download.

I just checked for the studs.

1x4 stud is 3718921 (page 85 of the AIM pdf, Sec 6 Sheet 3.00)
I did a search using gmpartswiki and for some unknown reason it only shows that part used for the Corvair.

http://www.gmpartswiki.com/getpage?pageid=3809

2x4 stud is 3728798 (page 188 of the AIM pdf, RPO 469 Sheet 1.00)
I found no entry for this. I'd imagine not available in service.

Rich

Rich,
I just checked my Oct. 63 and Jan. 66 Corvair-Chevy II-Chevelle parts catalogs and GM # 3718921 is not listed. The 3718921 must be longer that 3.37" long as shown on UPC C64, Sheet C3 of the Corvair AIM . My guess is that the length of the 3718921 stud must be at least 3 1/2" long, maybe 3 5/8". Another clue for the research.
Dave

[Bill B.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

Dave, to add to Bill's research....

2x4 stud is 3728798 (page 188 of the AIM pdf, RPO 469 Sheet 1.00)
I found no entry for this. I'd imagine not available in service.

Rich

Dave, sure you already have checked with the online 57 AIM and this illustration shows the dual quads with two small air cleaners that must have required a totally different length stud. And, then a running change at some point when the low profile air cleaner replaced them.

I also noticed that the FI studs were different 3719981 (w/o high lift cam & w/o air intake) and 3744846 (w/high lift cam & w/air intake). Knowing the FI units did not appear until mid-to-late 57 production and in a very small quantity, the "981" FI illustration page was drawn on September 15, 1956; but, although it appeared in the initial 57 AIM, it took many months before it actually appeared in production. Interesting to me.

[David L.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

Bill,
In my collection I have 1/4"-20-20 air cleaner studs that measure 3.38", 3.46", 3.61, 3.93", 4.03", 4.07", 4.25", 4.50", and 4.62" as well as shorter and longer ones. My research will continue as what else does one do when confined to a house.
Dave

[Bill B.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

I totally understand shut in as I my wife has trained me not to go past the end of our property line very similar to how I trained our little poodle to do same. I now understand why he gets excited when he sees a squirrel in the yard and runs after it...I saw a squirrel out the back door the other day and nearly ran outside and started chasing it!

Don't know if it will help but I have a very complete and correct 58 1x4 carb and think it has the stud in it. Give me couple hours and I will post the length and thread lengths. Realize that I cannot guarantee it is the real original stud but everything else on it was by the numbers. My dual quads are correct too but came without any studs.

[David L.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

Bill,
No need to get your hands dirty. I got some information about the studs via my email.
Thanks anyway,
Dave

[Joe L.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

I have a 58 AIM and I thumbed thru the pages looking for any air cleaner (FI, 2x4,1x4) illustrations which specifically showed "stud" with a part number. Following is what I found for you:

2x4 Application-Stud part number is 378921. Drawing date is June 26, 1958 and Revision note indicated released for 59 on August 15, 1958. Additionally, on August 18, 1958 Revision Record note indicates the stud was previously part number 1558773.

Fuel Injection-Stud part number is 3750005. Drawing dated June 26, 1957. Revision Record shows "Redrawn & Revised" on August 16, 1957.

1x4-Stud part number is 3718921. Drawing dated June 12, 1957. Revision Record shows "Redrawn" on May 15, 1958.

Looks to me that at least in 1958 both single and dual quad carbs apparently used the same "921" in late production and most likely this would have carried into 59 production. And, I assume the "921" was used in early 2x4 applications but early 1x4 started out using "773" until it was changed to "921". None of this information appears to be consistent with your above GM info?

Bill------


I cannot find that GM #378921, 1558773, 3750005, or 3718921 were ever available in SERVICE.

[Bill B.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

Bill------


I cannot find that GM #378921, 1558773, 3750005, or 3718921 were ever available in SERVICE.

I have only extracted what is published in the 58 AIM and not defending the accuracy of the AIM info? With your knowledge how often do you encounter issues like this and what do you attribute it to?

[David L.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

Bill,
Another NCRS member sent me an email with some valuable information about someone that makes reproduction 56-61 Corvette air cleaner studs. Now at least I know what they look like but I am still a bit confused.
Is the 56-57 stud GM #1558773 (4 5/16" long) and is the 58-61 stud GM # 3718921 ( 3 15/16" long)?
According to one of your previous posts GM # 1558773 was replaced by GM # 3718921 on 8/18/58 in the revision record.
Dave

http://www.paulmazutcorvette.com/services_parts/engine/56_-_61_2x4_carb_studs_with_2.html

[Bill B.]

Re: 57-58 Corvette w/4BC AIR CLEANER STUDS

Now that is some good information and I don't care what the numbers should be. The source is totally worth $12.00 for me to replace the two generic studs that I just recently purchased from a vendor. You do good work when your shut in.