1969 Corvette 3 x 2 Carb to Intake Manifold 9418918 BOLT MARKINGS

[David L.]

The 1969 Corvette AIM (UPC L71, Sheet A1) lists the 2 carb to intake manifold bolts on the left side as GM # 9418918. These bolts were sold over the counter as described as 5/16"-18 X 1" 280 M (Grade 5 with the 3 radial lines on the head of the bolt). For those who have original cars with this option what are the markings on these bolt heads ("WB", 'RSC". "RBW", "L5", etc.)?
Dave

[Wayne M.]

Re: 1969 Corvette 3 x 2 Carb to Intake Manifold 9418918 BOLT MARKINGS

Hi David -- I don't have a '69 car, but do have a late 400hp set-up with air cleaner that I've owned for about 30 years. Center carb list 4055, dated 981 and the front / rear carbs list 3659, and dated 951.

Can't say I've ever noticed these 2 bolts (are they to permit wrench access with the fuel lines installed ?).

Anyway, my 2 bolts have the hex circle divided into 3 equal segments {think a pie shared by 3}. There's a small triangle in one of the segments -- nothing else. Would take a photo except I'm temporarily camera-poor. Am not implying this is factory-correct, but it's what's on what I have.

[David L.]

Re: 1969 Corvette 3 x 2 Carb to Intake Manifold 9418918 BOLT MARKINGS

Wayne,
DocRebuild apparently had some reproduction 9418918 bolts with "WB" on the bolt heads listed for 67-69 dual quad Corvettes but is out of stock. The 67-68 Corvettes list GM bolt #122017 (UPC L71) but the 69 Corvette lists GM # 9418918.

To be "correct" I need 4 of these bolts to connect the 2 links to the rear stabilizer bar of a 1970 Camaro. The 9418918 bolts are listed as 5/16"-18 X 1" 280 M (grade 5 with 3 radial lines) with full thread length and I believe that they have a black chromium finish.

In my collection I have eight 5/16"-18 X 1" (grade 5 with 3 radial lines) with full thread length each with an "L5" marking on the head and they have a black chromium finish. These 8 bolts (which appear to be N.O.S.) were in a 57-61 Corvette dual quad intake manifold (Casting # 3739653) instead of studs that I bought at a swap meet back in the 1980's. I sold the intake but kept the 8 bolts because they were not "correct" for the intake. I know that GM bought bolts from several vendors as listed in my first post.

I was just curious what bolt markings were on the 2 bolts on an original 69 Corvette intake manifold w/dual quads.
Dave

[Chris H.]

21B0CE58-D8C7-4D31-969F-B70060E0E411.jpg

[David L.]

Re: 1969 Corvette 3 x 2 Carb to Intake Manifold 9418918 BOLT MARKINGS

Chris,
I assume that your Rockford bolt is 5/16"-18 X 1" with a full thread length. Do you think that the 2 Rockford bolts are original as I have never seen an original GM bolt with a Rockford marking but I have not seen all the different bolts from every bolt company that supplied Chevrolet with bolts. However, I do have some 7/16" Rockford bolts that I bought at my local hardware store many years ago to attached the bumper brackets to the frame on my 1966.
Dave

[Chris H.]

[David L.]

Re: 1969 Corvette 3 x 2 Carb to Intake Manifold 9418918 BOLT MARKINGS

Chris,
With 14.000 miles I would this that the bolts were original. It's just in the last 41 years I have gone to many salvage yards, many swap meets, etc., and have never seen GM bolts with a Rockford markings.
Dave

[Ronald L.]

Re: 1969 Corvette 3 x 2 Carb to Intake Manifold 9418918 BOLT MARKINGS

David,
"Black Chromium" I would like to see the specs on that - is it a 1960s 1970s industry corrosion preventative finish?
Would that have been the standard for a chassis part in 1970?

I really doubt that type of finish was even in the spec books, I only studied and tested materials to the GM Specs back in that time period for a few years, so perhaps is just memory. However I would suggest someone has the print for this bolt, if it was special fastener. If not, it would be the the GM Standards books that some NCRS members do have. Either way - that print will tell you what the finish was.

[David B.]

Re: 1969 Corvette 3 x 2 Carb to Intake Manifold 9418918 BOLT MARKINGS

#9418918 5/16-18 x 1 phosphate coated* GM 4435-M code A spec.

[David L.]

Re: 1969 Corvette 3 x 2 Carb to Intake Manifold 9418918 BOLT MARKINGS

Ron,
I got the idea about the finish of the 9418918 bolts from the link below. I guess that I meant black phosphate but I actually typed black chromium, an error on my part. I had just added some 1970 Camaro black chromium wiper arms and blades for sale on a Camaro site. This is what happens with getting old. Thanks for the "wake up call".
Dave

1967-1969CorvetteHolley3x2CarbMountWBBoltGenuineGM94189 18NOS.aspx

[Ronald L.]

Re: 1969 Corvette 3 x 2 Carb to Intake Manifold 9418918 BOLT MARKINGS

Thanks David, those are some nice bolts and NOS to boot, yes black phos, used to redo lots of those back in the resto days, normal phos solution was a much lighter gray, I no longer remember what I was told to put into the solution to achieve the dark color...