Author Topic: Carb Stud Length - '69 Cowl Air Cleaner  (Read 2352 times)

Edgemontvillage

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Carb Stud Length - '69 Cowl Air Cleaner
« on: March 09, 2013, 06:36:46 PM »
The cowl hood (original paint) and air cleaner assembly on my '69 Z/28 are original however at some point a few fasteners lost their way... including the air cleaner stud, and I have been painstakingly trying locate correct originals. The air cleaner stud seems to be a particular challenge.  The commonly available era correct stud is ~2.25" total length, the lower segment that screws into the carb is ~0.50" and upper segement that secures the cleaner lid and filter element is ~1.75".  I use an AC Delco repop 212CW air cleaner element which measures ~3.00" in height and an original 4053 carb with paper gasket.  I understand the original 212 element was also 3.00" high.

The stud has a lot (no photo) of excess thread length above the top of the air cleaner lid with the wing nut secured and doesn't look right. What is the correct total and segment lengths of an original cowl air cleaner stud and are there any differences vs a non-cowl hood open element stud? I am also interested in how the top of the stud was finished/cut. The stud in the photo is tapered rather than bunt cut  ???









Lloyd
1969 RS Z/28 (Brooklyn Project)

69Z28freak

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Re: Carb Stud Length - '69 Cowl Air Cleaner
« Reply #1 on: March 10, 2013, 07:12:08 AM »
Nice work Lloyd.
Mike 1969 Grandma Camaro

rszmjt

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Re: Carb Stud Length - '69 Cowl Air Cleaner
« Reply #2 on: March 10, 2013, 02:38:08 PM »
Lloyd,

The stud in the photo looks correct for a cowl hood car, however I think your wing nut is not the original, it looks to bulky in the wing thumb hold area. The wing nut should not be chrome, and the stud ( i think) is like a dull black phosphate. I had changed mine many years ago ( put a chrome lid and stud/nut off a non cowl hood car) and in going through my original kept parts for my car ( reinstalled), just came across it and the wing nut, ( as well as the lid) I will snap a picture Monday and repost it for you. 

copo

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Re: Carb Stud Length - '69 Cowl Air Cleaner
« Reply #3 on: March 10, 2013, 07:03:45 PM »
In the AMK products catalog it shows the stud with part 3747933 as 1/4 20 x 1 5/8 OAL. This part number of the stud # 3747933 is listed in the cowl induction section of the AIM. This length of the stud appears to match the original engine photo of the # 3 ZL1 camaro in a book I have.

Edgemontvillage

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Re: Carb Stud Length - '69 Cowl Air Cleaner
« Reply #4 on: March 10, 2013, 07:32:33 PM »
Lloyd,

The stud in the photo looks correct for a cowl hood car, however I think your wing nut is not the original, it looks to bulky in the wing thumb hold area. The wing nut should not be chrome, and the stud ( i think) is like a dull black phosphate. I had changed mine many years ago ( put a chrome lid and stud/nut off a non cowl hood car) and in going through my original kept parts for my car ( reinstalled), just came across it and the wing nut, ( as well as the lid) I will snap a picture Monday and repost it for you.  

Would be great if you would post a photo of an original, thanks Mike.

rszmjt

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Re: Carb Stud Length - '69 Cowl Air Cleaner
« Reply #5 on: March 10, 2013, 07:46:19 PM »
In the AMK products catalog it shows the stud with part 3747933 as 1/4 20 x 1 5/8 OAL. This part number of the stud # 3747933 is listed in the cowl induction section of the AIM. This length of the stud appears to match the original engine photo of the # 3 ZL1 camaro in a book I have.

AMK studs are not correct, they are close but slightly shorter, I just got 1 for a Restoration I am doing on another 69Z, the original correct production line installed GM stud is over 2.25 and it looks goofy as it sticks through the wingnut quite a bit when the lid and filter is installed.
 I will take a picture of mine and repost Monday, my Z28 is at the shop.

69Z28freak

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Re: Carb Stud Length - '69 Cowl Air Cleaner
« Reply #6 on: March 11, 2013, 06:44:46 AM »
I wonder if the wing nut on my original car is correct? Were all wing-nuts created equal?

rszmjt

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Re: Carb Stud Length - '69 Cowl Air Cleaner
« Reply #7 on: March 11, 2013, 04:12:16 PM »
I wonder if the wing nut on my original car is correct? Were all wing-nuts created equal?

No, original 6 cylinder wing nuts have a flat bottom, pretty sure I have a correct 1 for Lloyd

69Z28

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GaryC

'UNRESTORED' 1969 Cortez Silver X33D80 Z28

rszmjt

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Re: Carb Stud Length - '69 Cowl Air Cleaner
« Reply #9 on: March 11, 2013, 07:06:09 PM »
Lloyd, your stud is a little too long. IMO. I can only measure mine from the flange up, but it is 1.500 from the top of the flange to the top of the stud. Mine appears to have a smaller unthreaded shank area above the flange. Original cowl hood wingnuts are plain steel and have small thumb wings, BTW. I have also included the correct short stud and chrome wing nut for non cowl hood cars, as well as the current repo AMK chrome wingnut compared to a known GM original which appears flash plated much like GM chrome valve covers.. Notice the thumb wings on the AMK wingnut are much bigger and extend to the inside more. I have heard that 67 427/435HP Corvette studs are the same, but I just measured 2 known originals, 1 a 6,000 Mile survivour and they are both 1.422 and 1.415 from top of flange to top of stud.
As far as I know mine is original, I have owned this RSZ28 since 1973.

Edgemontvillage

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Re: Carb Stud Length - '69 Cowl Air Cleaner
« Reply #10 on: March 11, 2013, 11:23:42 PM »
Mike, thanks for the posting, that's excellent information and the photos help a great deal!  For completeness of topic and future reference, do you have, and would you post the measurements for the non-cowl stud as well.

 

rszmjt

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Re: Carb Stud Length - '69 Cowl Air Cleaner
« Reply #11 on: March 11, 2013, 11:30:09 PM »
Mike, thanks for the posting, that's excellent information and the photos help a great deal!  For completeness of topic and future reference, do you have, and would you post the measurements for the non-cowl stud as well.

 

1.505 Overall Length,machined raised portion in middle .265 long X .312 wide, threaded length .620 both ends

Edgemontvillage

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Re: Carb Stud Length - '69 Cowl Air Cleaner
« Reply #12 on: March 13, 2013, 06:29:42 AM »
Thanks for the additional details Mike.


69Z28freak

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Re: Carb Stud Length - '69 Cowl Air Cleaner
« Reply #13 on: March 14, 2013, 04:41:39 AM »
Well done Mike. Always great to get info from you. Perhaps you can help me with some of my questions. I started a few threads here and on Team Camaro. You detailed responses are excellent and informative.

Thank You