Nuts & Bolts Question 67 Fan Shroud/DS Horn

[Kirk M.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Kirk,

Thanks very much for the pictures, looks very similar to the bolt I think Tim is referring to. Is it a 5/16-18 x 3/4" bolt with a 3/4" diameter attached serrated washer? If so, it has the same length (and thread) as the regular 122007 fan shroud bolt. Is it 1/2" across-the-flats?

I will try and get some measurements tonight. I've had that bolt in and out about five times now.

Kirk

[Scott S.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

I will try and get some measurements tonight. I've had that bolt in and out about five times now.

Kirk

Thanks Kirk.

It should be 5/16-18 in order to fit the bolt-hole, and your pictures show it is an indented hex with attached conical serrated flat washer, with a flat tip. I think the only dimensional info we still need is:

1. the bolt-head across-the-flats / wrench-size measurement
2. the length (from underside of head to flat tip)
3. the diameter of the attached washer

There were several bolts of this general style that were used on these cars, all looking similar, with the primary differences being flat tip vs. pointed tip, the diameter of the attached washer (5/8" vs. 3/4") and different lengths (5/8", 3/4", 7/8"). Small differences, but each corresponds to a different part number.

[Henry S.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Thanks Kirk.

It should be 5/16-18 in order to fit the bolt-hole, and your pictures show it is an indented hex with attached conical serrated flat washer, with a flat tip. I think the only dimensional info we still need is:

1. the bolt-head across-the-flats / wrench-size measurement
2. the length (from underside of head to flat tip)
3. the diameter of the attached washer

There were several bolts of this general style that were used on these cars, all looking similar, with the primary differences being flat tip vs. pointed tip, the diameter of the attached washer (5/8" vs. 3/4") and different lengths (5/8", 3/4", 7/8"). Small differences, but each corresponds to a different part number.

Scott,
Are there several places on the midyears you would find 5/16-18 bolt with a serated washer?

[Scott S.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Scott,
Are there several places on the midyears you would find 5/16-18 bolt with a serated washer?

Hi Shooter,

The only examples with attached/captured serrated washers that I have learned about so far, are the 1963-only hood-hinge to hood bolts, also used on the radio in '63. Someone with a 1963 AIM database would need to search "3795488" to see if that bolt ("Screw Asm.") is used anywhere else besides the hood hinge and radio attachment.

I would have to check the archives, but I think there have also been some early midyear screw assemblies mentioned with serrated washers on the seat track/floor bolts. In my archive searches, I see at least two recurring problems involved in identifying these kinds of things correctly:

A) the part numbers often changed from year to year, and people having different model years end up talking apples-and-oranges without realizing it;

B) there are several of these screw assemblies that are very similar, and they also changed from year to year (particularly the seat-track to floor bolts). The archives are contradictory on many of them, in part because the differences are small. For example, going by fairly recent memory, some have posted that the 3847757 bolt has a pointed tip, others that it has a flat tip. Some said it was 7/8" long, others said it was 1" long, and others said it was 5/8" long. Sometimes it was the same person saying two different lengths in two different threads, other times one person says it's either 5/8" or 7/8" in the same thread (it can't be both!)

With the differences being so small (i.e., 1/8" increments), guessing or "eyeballing" it leads to more confusion - we need measurements

[Kirk M.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Thanks Kirk.

It should be 5/16-18 in order to fit the bolt-hole, and your pictures show it is an indented hex with attached conical serrated flat washer, with a flat tip. I think the only dimensional info we still need is:

1. the bolt-head across-the-flats / wrench-size measurement
2. the length (from underside of head to flat tip)
3. the diameter of the attached washer

There were several bolts of this general style that were used on these cars, all looking similar, with the primary differences being flat tip vs. pointed tip, the diameter of the attached washer (5/8" vs. 3/4") and different lengths (5/8", 3/4", 7/8"). Small differences, but each corresponds to a different part number.

Here are the measurements that I got:

1. 1/2" bolt head
2. 13/16" was the length of the bolt (I measured and re-measured it several times to be sure)
3. 3/4" diameter washer

1 and 3 seem to match your measurements but the bolt length seems to fall in between the 3/4" and 7/8" lengths you listed. As I said, I realized that and kept measuring and remeasuring it and could not make it come out to be anything but the 13/16".

Kirk

[Ronald L.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

Kirk,
if you are looking at the 122007 bolt, there is a lot about that bolt on this forum.


Yes WB is a popular headmark as its been reproduced. I submit though knowing you have a 67 that WB just might not have been the head mark used when your car was assembled.

What you need to do is look at all the other usages - and it helps if your car has not been wrecked or tampered with.
Key areas to look for the same part:
pencil braces from the bottom of the grille up into the head lamp pockets. These are hard to get at and don't get messed with but on front end crashes and restorations.

Thru-exhaust - the rear hangers - what do you have there?
If an original 427 car - the rear brackets that bolt to the control arms - the #1 area that gets changed. On AC cars there are a couple of others.

Next on the WB or what I expect you to find on an unrestored car, an RSC, the length under the head is about 3/4" .

This bolt figures on the one-page chart that was posted several times here too.

If you are looking at standard bolts, in the series such as this 122007, they won't have special flanged heads, captured lock washers and the like. Those carried special part numbers.

The horn mounts on the 66 67 also were RSC - but a grade 5 with 3 bars and they were shorter - more like 5/8" under the head.

Did you get pics of the correct u-nut? They are hard to find and not reproduced though I know of at least one source for a set of these.

The other thing to get your hands onto is the database of all the part numbers in the AIM, that way you can sort and find other areas the same part was used on your car, or any mid year for that matter. Its a wonderful tool!

[Scott S.]

solid data point (carefully measured), an unusual length, and something to compare with other examples.

Thank you very much for going the extra mile. As someone who spends a lot of time trying to figure these things out, I appreciate it

[Kirk M.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

solid data point (carefully measured), an unusual length, and something to compare with other examples.

Thank you very much for going the extra mile. As someone who spends a lot of time trying to figure these things out, I appreciate it

Not a problem. I think it's kinda fun to work through things like this.

Kirk

[Henry S.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

The other thing to get your hands onto is the database of all the part numbers in the AIM, that way you can sort and find other areas the same part was used on your car, or any mid year for that matter. Its a wonderful tool!

Ron, where can this database be found? I have the "Corvette Parts Book" (1953-1972) by Motorbooks International. Was hoping there is a more "user friendly" one available. Thanks, Shooter

[Stephen G.]

Re: Nuts & Bolts Question 67 Fan Shroud/DS Horn

I just started reading this thread from earlier this month. I have a question about the horn itself on a 67 400 HP A/C car). Did the horn bracket get bent so that the horn was forward of the AC condenser coil or did it butt into the side of the AC condenser?

Currently my horn blows partially into the side of the condenser coil and horizontally across the front of the car. (If that makes any sense to you)...