57-58 Corvette w/4BC AIR CLEANER STUDS

[Joe L.]

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

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

Dave-----


Assuming that the studs you have are actually GM studs, they are likely either GM #3825532 or, possibly, GM #3777266. The 3825532 was 3-5/8" and the 3777266 was 3-1/4".

Most of the GM carb studs available in SERVICE were eventually discontinued in favor of the GM #3785256 which was 9" in length and almost just a length of all-thread rod (but with a very short unthreaded section in the middle). The exception was the GM #3777266 was discontinued without supercession in October, 1971. I suppose that GMSPO finally decided that inventorying all these different carb studs was unnecessary. Mechanics could simply cut the 3785256 to the required length.

[David L.]

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.

Bill,
Paul Mazut Corvette also makes the 58-62 Corvette F.I. studs, GM # 3750005, I assume. However, the thread lengths are not the same on the two studs. The top 1/4"-20 stud in the photo has about 17 threads (about 7/8") at the tapered end and 20 threads (1") at the other end. The bottom stud in the photo has about 60 threads (3") at the tapered end and about 10 threads (1/2") at the other end. Based on the fact that there are 20 threads per inch I would estimate that the length of the two studs is about 8 3/8", 8 1/2", or 8 5/8" or something close to that.
Dave

http://www.paulmazutcorvette.com/services_parts/engine/58_-_62_fl_air_cleaner_stud_2.html

[David L.]

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

Dave-----


Assuming that the studs you have are actually GM studs, they are likely either GM #3825532 or, possibly, GM #3777266. The 3825532 was 3-5/8" and the 3777266 was 3-1/4".

Most of the GM carb studs available in SERVICE were eventually discontinued in favor of the GM #3785256 which was 9" in length and almost just a length of all-thread rod (but with a very short unthreaded section in the middle). The exception was the GM #3777266 was discontinued without supercession in October, 1971. I suppose that GMSPO finally decided that inventorying all these different carb studs was unnecessary. Mechanics could simply cut the 3785256 to the required length.

Joe,
The 3 studs in my photo are 3 3/8" long. I have one more 3 3/8" stud that is exactly the same as the 3 in the photo and it was removed from a 1966 Chevrolet with 2BC 283 engine many decades ago. The part number in the 1966 Chevrolet AIM (UPC 6, Sheet C2) is 3750992. There is no question in my mind that the part number of the 3 studs in my photo is 3750922. This same part number also appears in my 1963, 1964, and 1965 Chevrolet AIM's for the 283 2BC engine. These studs were very common in the 1960's.

Also, I have two 3 5/8" long air cleaner studs that I have yet to determine the application.
1. One of then has thread lengths of 1" on each end and is similar to the 3 studs in the photo.
2. The other 3 5/8" stud has a 1/16 inch wide, 0.40" diameter, "washer" located 1 9/16" to 1 5/8" from the top end in the non-threaded part of the stud. The thread lengths are 1 3/16" at the top end and 13/16" at the bottom end.
Possible part numbers so far are 3818717, 3854534, 3864802, and 3825532.
Dave

[Joe L.]

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

Joe,
The 3 studs in my photo are 3 3/8" long. I have one more 3 3/8" stud that is exactly the same as the 3 in the photo and it was removed from a 1966 Chevrolet with 2BC 283 engine many decades ago. The part number in the 1966 Chevrolet AIM (UPC 6, Sheet C2) is 3750992. There is no question in my mind that the part number of the 3 studs in my photo is 3750922. This same part number also appears in my 1963, 1964, and 1965 Chevrolet AIM's for the 283 2BC engine. These studs were very common in the 1960's.

Also, I have two 3 5/8" long air cleaner studs that I have yet to determine the application.
1. One of then has thread lengths of 1" on each end and is similar to the 3 studs in the photo.
2. The other 3 5/8" stud has a 1/16 inch wide, 0.40" diameter, "washer" located 1 9/16" to 1 5/8" from the top end in the non-threaded part of the stud. The thread lengths are 1 3/16" at the top end and 13/16" at the bottom end.
Possible part numbers so far are 3818717, 3854534, 3864802, and 3825532.
Dave

Dave------


Yes, you're correct. I blew it on this one. I don't know what I was thinking when I said the ones you pictured were 3-5/8" GM #3825532. They are almost certainly the 3750922.

The 3-5/8"studs you have could be either the 3818717, 3854534 or 3825532. I don't have any specs on the 3864802.

[Bill B.]

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

[QUOTE=David Liukkonen (3775);867929]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/QUOTE]

Just noticed you were asking a question about my previous post. Have no idea on lengths.

[David L.]

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

Dave------


Yes, you're correct. I blew it on this one. I don't know what I was thinking when I said the ones you pictured were 3-5/8" GM #3825532. They are almost certainly the 3750922.

The 3-5/8"studs you have could be either the 3818717, 3854534 or 3825532. I don't have any specs on the 3864802.

Joe,
The 3864802 air cleaner stud is listed in my 1966 Chevrolet AIM (UPC L30, Sheet A3.5) for a 327 engine using a Rochester carb #7026203 or Carter carb 3826749 (possibly misprint as 1966 parts catalog lists 3876749). The 3869954 air cleaner stud (1/4"-20-20 X 2") is listed for used with a 3876747 Holley carb. Many years ago I marked the 3864802 stud as 3 5/8" long in this AIM.
I think that I wrote 3 5/8" next to 3864802 in the AIM because back in the 1980's I bought a complete 1966 Chevrolet 327 engine in a salvage yard in Orange, MA, for $25. All the components (carb, alternator, starter, 4657 AC fuel pump, intake, etc.) had date codes that matched up with the date code stamping on the engine pad "T0521HAR" (Tonowanda, May 21st, 327 w/M.T., and "R" for Rochester carb). The block casting was with "E 13 6" or "E 18 6" (May 13th or 18th, 1966). I assume that the 3864802 stud was still attached to the carb which I sold many years ago.
I have no other evidence to prove that the 3864802 stud is 3 5/8" long.
BTW, the 3864802 stud and the 3869954 stud are also listed in the 1966 Chevrolet AIM (UPC L35 L36, Sheet A9) for 396 & 427 engines depending upon which carb was installed on the assembly line.
Attached is a photo of two air cleaner studs that are 3 5/8" long. One of them might or might not be GM # 3864802. I may never find out but that is what makes it a challenge.
Dave