1967 Big Block Fan Shroud

[Enzo C.]

Re: 1967 Big Block Fan Shroud

BCB73617-0264-4D69-B01C-87AD66167319.jpg01BB8B77-2D87-4808-9332-E4079249C11B.jpgHere you go Joe.

[Joe L.]

Re: 1967 Big Block Fan Shroud

[ATTACH=CONFIG]104605[/ATTACH][ATTACH=CONFIG]104604[/ATTACH]Here you go Joe.

Enzo------

Thank you.

This looks like an earlier version of the GM #3938940. It's a 1968 model year shroud that was used in SERVICE for 1966-67 big blocks beginning in early 1970.

There should be part numbers on each of the 3 components of the shroud (left side, right side, and upper). The numbers may be either on the inside or outside surface of each component. I can't see them in the photos. Can you tell me what they are? They will be 7 digit numbers beginning with either 38 or 39.

[Enzo C.]

Re: 1967 Big Block Fan Shroud

Yes Joe you are correct.. they are on the inside and DS and general Tire
388269
3911110
3886887

[Mark M.]

Re: 1967 Big Block Fan Shroud

Enzo, nice pictures. That shroud has the 68 molded shapes in all 3 parts, but as you said it has 67 #'s cast in. The top part has the hole for the bracket offset as needed for a C2. C3 cars had the hole in the middle. It seems that shroud was made for C2 use. I have a few 68 427 shrouds which look similar to the one you have pictured except the #'s are for 68 and holes are factory made in the middle for C3 cars.

[Joe L.]

Re: 1967 Big Block Fan Shroud

Yes Joe you are correct.. they are on the inside and DS and general Tire
388269
3911110
3886887

Enzo------

Attached are photos of an NOS GM #3938940 that I purchased from GM about 30 years ago. The 3938940 was discontinued without supersession in September, 1995.

Note that the upper component of the shroud has the embossed 3938940 assembly part number, The left and right side components have the 1968 part numbers of 3935571 and 3935572. The 1968 upper part number, GM #3935569, does not appear on the upper component. None of the 1968 shroud component parts were ever available separately in SERVICE.

Apparently, the 1967 shroud component part numbers, GM #3888269, 3886887, and 3911110, which were all once available separately, were revised via a change to their specifications in order to accommodate the 1968 requirements. This whole shroud situation is very unusual and exceedingly rare.

DSCN3882.jpgDSCN3881.jpgDSCN3875.jpgDSCN3879.jpgDSCN3880.jpg

[Ronald L.]

Re: 1967 Big Block Fan Shroud

Joe,

Enzo's shroud was installed on a '67, so by default, someone would have drilled this before installation. If not, they would have found out in short order and torna lot of the shroud and fan blades up, but given they spun the blades and saw the crash condition, would have put the correct hole in there.

On your shroud...
The shroud you purchased has the distinct multiple rivets of the very late service parts for these BB shrouds.

The early service and or production parts would have -- at most -- had rivets in the Right side that was notorious for separating.

Along the way you can see variations of the numbers that were stamped into the dies, providing the relef part numbers we see today.

The next couple of posts will shown some 68 service parts, center part, right part number area and left. THere are some subtle differences, and notable a much more pronounced part numbers and GT logos in the later parts.

[Ronald L.]

Re: 1967 Big Block Fan Shroud

68 shroudsIMG_3764.jpgIMG_3765.jpgIMG_3766.jpg

This one was drilled and installed on a mid-year. It was a service part that had the center hole drilled, the hole position was added, and you can see that both were filled, there is some die mold release materials showing in white.

[Ronald L.]

Re: 1967 Big Block Fan Shroud

another 68IMG_3767.jpgIMG_3768.jpgIMG_3769.jpg

[Ronald L.]

Re: 1967 Big Block Fan Shroud

IMG_3779.jpgIMG_3780.jpgIMG_3781.jpg

This one is notable different in that the GT logo is on the upper piece very pronounced.
This and about 5 others are all NOS, never installed....
I've noted a slight notch to the core support that is not present on this presumed later shroud.

[Enzo C.]

Re: 1967 Big Block Fan Shroud

Wow Joe... and here is another variable option that General Motors created or had created
unreal in the variances and mish mash of parts for 66,67,68

[Mark M.]

Re: 1967 Big Block Fan Shroud

All these shrouds and replacement upper parts that I've seen sb or bb ,have one hole drilled at the factory. Center drilled for C3, offset corner for C2 427 cars. Any repair to change that hole location, would be detectable. Enzo, is there any indication of a repair in the center area. Any paint there must be removed. If no repair, that shroud was most likely made as a C2 replacement. Later the 68 replacement was used for C2 by drilling the offset hole or as Ronald mentioned, using the predrilled hole could cause the top part to get chewed up by the fan. I have 68 427 shrouds with the offset hole added for C2 use.
I was hoping owners with very late 67 427 cars with original shrouds could help to answer if they had the letters GT cast in their shrouds. The 2 small letters could have easily been added to the 67 production dies. Small change, when? My guess is it stands for General Tire. Pictures are in Tom's link up above. It seems there where 2 production versions of 67 427 , and 3 maybe more versions of the 68 which could fit a 67 for replacement.

[Ronald L.]

Re: 1967 Big Block Fan Shroud

Mark,
You are spot on, even on the 68 parts, early parts for sure, the DS logos were left in the tool.

In the 70's, speaking of Corvette fiberglass parts in the GMPD serive parts system, you can see X's through earlier part numbers in the molds when a different supplier took over the contract and a change was made.

Speaking to Enzo's comment - if on the day of Job 1 1966 model year you looked at the part numbers, they were very stable and simple, the three pieces in the 1966 AIM that were assembled at St Louis Assembly plant, in the basement if memory is correct of John Hinckley's presentation at one of the Nationals on the Assembly Process...

Moving forward - there was at least the change to the right side to gain clearnace to lower rad hose control arm etc, some hose routing, lets just say - part reliability improvements over 1966. If we had the print, we would be able to identify this change over. Having said that we have not heard of any early 1967 Big Block Owners having a 66 shroud in their cars, nor 66 owners, however my Estimate having worked there is that this was done in the summer of 66 and was ready for the pilot builds in August of 66...

Still pretty simple.

1968 hearalded in the new C3 slanted back to get under the lower hood and narrower body, the dies got changed - because that was the right thing to do financially, not because 66 or 67 owners 55 years later would need a correct shroud.

So for those needing one, you have to keep in mind a 66 or 67 big block car essentially got crashed (not too bad in the front), or got all the radiator items pulled to build a race car... in order for us to have one extra. An then you have to keep in mind that there are more tri-power cars out there than left St Louis...

Really simple if you're in the Engineering and manufacturing space...

Enjoy!

[Enzo C.]

Re: 1967 Big Block Fan Shroud

Hi Mark can I call you