67 BB Fan Shroud U-nut Help

[Dereck S.]

At last year's National Convention at Charlotte I spent a great deal of time looking at 67 fan shroud u-nuts on BB cars. There were several versions of u-nuts on cars being judged as well as on two "survivor" cars. I'm interested in learning what u-nuts are correct for 66-67 BB cars. Below is what I have found along with pictures for feedback. The u-nuts are identified as 1,2,3, and a picture of four nuts that I believe are correct for the BB application.

1. Nut #1 was seen at the convention on one BB car being judged. It has a square nut with mushroomed corners with no other markings or features.
2. Nut #2 was seen on one BB car being judged as well. It has a square nut with no mushroomed corners. The back of the clip is shortened with the stamped numbers T5618 087-093. This nut also has a raised rib down the center.
3. Nut #3 was not seen on a car at the convention but has a square nut with very promanant mushroomed corners. It also has a raised rib down the center.
4. The four nuts in the separate picture are off a 67 sent to me by another NCRS guy. All are a square nut with mushroomed corners and a round dimple on the face. There is also a stamped marking on the back shown in another picture. These were on the "survivor" cars at the convention and believed to be original. The third pic is of the backside showing the stamp.

Now for the big question. Out of all the nuts shown and listed which are definately correct for a 66-67 BB fan shroud? Which are from steel cars to attach body panels together? How are these judged at events?

Thanks,
Dereck

[Ronald L.]

Re: 67 BB Fan Shroud U-nut Help

Dereck,
It helps to see a side view and the back of all of them.

These were on these BB's three years only 66 67 and 68 and two styles have been seen, I attribute the difference to the height of the nut within the clip and 66 67 are the same with 68 being higher. My observation has been off of original 66 67 parts, not show cars that you never really know where they have been. There's sure to be other opinions. Most of these details were posted here last summer.

Clip #2 of your pictures is NOT fan shroud, it is either a trans clip or a sheat (pun)metal part.

So the pics in your second photo from the other NCRS-er are what I recognize as 66 67 with the dimple and the logo on the back.

[Dereck S.]

Re: 67 BB Fan Shroud U-nut Help

Ronald,
Thanks for the feedback. Attached is a pic of the backside of each u-nut. Tough to see details but other than #2 there are no stamps or markings.
Dereck

[Ronald L.]

Re: 67 BB Fan Shroud U-nut Help

Dereck,
No markings, then they'd not seem to be the original style for 66 67.

[Keith B.]

Re: 67 BB Fan Shroud U-nut Help

I would say that the second photo is what I have seen also. Ron is a true expert at the shroud and the nuts. Please make sure that these get forwarded to the writers of the the judging guide. Thanks this is educational.

[Scott S.]

Re: 67 BB Fan Shroud U-nut Help

At last year's National Convention at Charlotte I spent a great deal of time looking at 67 fan shroud u-nuts on BB cars. There were several versions of u-nuts on cars being judged as well as on two "survivor" cars. I'm interested in learning what u-nuts are correct for 66-67 BB cars. Below is what I have found along with pictures for feedback. The u-nuts are identified as 1,2,3, and a picture of four nuts that I believe are correct for the BB application.

1. Nut #1 was seen at the convention on one BB car being judged. It has a square nut with mushroomed corners with no other markings or features.
2. Nut #2 was seen on one BB car being judged as well. It has a square nut with no mushroomed corners. The back of the clip is shortened with the stamped numbers T5618 087-093. This nut also has a raised rib down the center.
3. Nut #3 was not seen on a car at the convention but has a square nut with very promanant mushroomed corners. It also has a raised rib down the center.
4. The four nuts in the separate picture are off a 67 sent to me by another NCRS guy. All are a square nut with mushroomed corners and a round dimple on the face. There is also a stamped marking on the back shown in another picture. These were on the "survivor" cars at the convention and believed to be original. The third pic is of the backside showing the stamp.

Now for the big question. Out of all the nuts shown and listed which are definately correct for a 66-67 BB fan shroud? Which are from steel cars to attach body panels together? How are these judged at events?

Thanks,
Dereck

Picture two (fronts, with "WB" bolts) and picture three (back with angular "G" stamp) are the same as I have (1967, L79).

[Michael M.]

Re: 67 BB Fan Shroud U-nut Help

Dereck, as long as its a u-nut it should judge OK. The u-nuts with the dimple are the most common. The only other thing I would say is that the nut itself should have the corners cut off. In the first picture the middle u-nut would not be correct for 1967 because the nut itself is square. I have seen four different versions of u-nuts for fan shrouds and all the u-nuts have the corners of the nuts cut off.

[Ronald L.]

Re: 67 BB Fan Shroud U-nut Help

The nut with the dimple and a diamond shaped G on the back is what I see off 1967 shrouds, original & non molested.

The notches on the corners are where they are pinched over in the forming operation, not really cut off.

And to go out on a limb, you'll be hard pressed to tell me GM dual sourced a clip that the total take rate into STL was 100,000 ( 25k cars by 4 each) a year.

Fastener suppliers like to run these by the millions, and this was s special SMC only fastener versus all the other similar clips designed for multiple layers of sheet metal.

The fact that some Camaro clips that look close get on these cars is understandable and a simple matter of people finding a look alike in a hobby where there is no reproduction part. The clips GM had for the service parts were so different no one could be fooled.

If you are looking for them, patience, and one or two of our members just might have some.

Also, you will note the design of this clip was such that it snapped into the center of the slotted hole is such a way that removing them from the SMC has usually meant a torn out corner hole. If you plan on removing them, use caution as they are also fragile to fracturing (in half) on prying them open to get the lock past the smc, don't ask me how I know...

[Dereck S.]

Re: 67 BB Fan Shroud U-nut Help

Thanks Ronald and to all who replied. I ended up buying a completely beat up 67 shroud just to get the original u-nuts off it. Based on what I noticed at the Convention as well as trying to locate some of these it is understandable to use something that appears visually similar. I'll let the judges sort that one out. They are tough to find. Purhaps the TIM should reference the specific features of the correct u-nut (i.e. dimple, mushroomed corners, angular "G" stamp, etc) to help guide others. Then again, the info in this thread should help a lot.
Dereck

[Mark M.]

Re: 67 BB Fan Shroud U-nut Help

I'm restoring a 67 with L68 427 right now and it came with a lot of but not all it's original hardware.Two shroud u-nuts are like example #3 in first picture except one has a dimple above square nut and one doesn't. The other two have hex heads. I'm not sure if this helps but I'm also trying to find out what was used here in 67 BB.

[Ronald L.]

Re: 67 BB Fan Shroud U-nut Help

The hex was not on 67's from the factory. There have been this month a couple 67-only BB shrouds sold with original clips and there is one 67 327 shroud for sale with three of its original clips.

All are square.
All have a diamond symbol on the back that is "G" the name of the original manufacturer.
The height difference I have seen also seems to correlate to a difference in that "G".

They all have the small dimple too.

I think we'll find that hex was a GMPD service action of the late 70's so as to not have so many parts in the system. In 1975 I'm pretty sure you could get the "service shroud for 66-68 427" and the clips would still be square.