66 390 HP w/A/C Question

[Loren Lundberg (912)]

A friend has a 66 BB with A/C - the question deals with the SEAL(s?) on the radiator shroud/support. Nothing shows up (in my AIM) under the L36 section. When I go to the C-60 (A/C) section, page B2.5, the first thing I notice is that the drawing was "Redrawn & Redesigned" on June 8, 1966.
His car was built BEFORE then - any idea of what has changed on this drawing? Using the drawing, am I correct when I say:

1. ALL cars get the Upper seal

2. Seal 3901940 (SBC) is installed VERTICALLY on the support.

3. Seal 3889476 (BB) is installed HORIZONTALLY on support.
(What is the difference in these two seals?)

4. Seal 3887426(8?) (SBC) and # 3887465 (BB) attach to the radiator
SHROUD.
(What is the difference in these two seals?)
Does anyone like the good Dr Rebuild sell the correct seals?
Thanks.

[Joe Lucia (12484)]

Re: 66 390 HP w/A/C Question

Loren-----

The main thing that changed from the prior-to-6/8/66 revision is the addition of the revised upper seal AND a change in the lower seal for small block A/C applications. The original upper seal used 1966 with A/C applications was GM #3889475. This was a more-or-less rectangular cross-section seal. The revision added the GM #3901941 seal for all 1966 A/C applications. The 3901941 seal is of a completely different design than the 3889475 and it is MUCH more efficient in accomplishing its task than the former.

The other change to the drawing which also necessitated the addition of the revised illustration shown in the upper left quadrant of the page was the change in the lower seal for small blocks. Prior to this change the same lower seal, GM #3889476, was used for both small and big blocks although the installed orientation of the seal was different for each. The revised seal, GM #3901940, had rectangular "notches" pre-cut in the seal to clear the small block radiator support brackets. The latter seal was never available in SERVICE, though. For SERVICE, only the 3889476 was available and, for small block applications, you had to cut your own notches.

In answer to your specific questions:

1) Yes, all cars WITH A/C got the 3901941 seal AFTER the revision was incorporated on the actual assembly line. In point of fact, I believe that few, if any, 1966 models actually received it in PRODUCTION. The GM #3889475 was used for most, if not all, 1966 Corvettes with A/C;

2) Seal GM #3901940, used for small blocks, installs VERICALLY on the lower HORIZONTAL member of the radiator support;

3) Seal GM #3889476, used for big blocks, installs HORIZONTALLY on the lower horizontal member of the radiator support. The illustration in the lower left quadrant of the 6-8-66 revision to sheet B 2.5 incorrectly shows the lower portion of the big block radiator support. The big block support has no lower member-mounted brackets for the radiator. Instead, the big block support uses "u-shaped" brackets mounted to the support lower SIDE MEMBERS;

4) The radiator shroud seals, GM #3887426 and 3887425 used for small block and big blocks, respectively, were different in configuration and length to conform to the differences in the small block and big block fan shroud front surface where they mounted. These particular seals were NEVER available from GM in SERVICE.

I don't think that 1966 Corvettes with A/C ever used side seals for the support-to-shroud interface. For 1967, though, side seals were added to A/C applications.

If I had a 1966 Corvette, early or late, big block or small block, A/C or not-A/C, or a 1967 Corvette without A/C I would MOST DEFINITELY add the complete package of seals used for 1967 A/C applications. This includes the upper seal used, possibly, for late 1966 A/C and all 1967 A/C applications, the lower seals used for 1966 and 1967 with A/C and the side seals used for 1967 with A/C with NO REGARD WHATSOEVER for "points loss". ABSOLUTELY! POSITIVELY!

Dr. Rebuild carries absolutely OUTSTANDING reproductions of the above-referenced seals. However, I don't think that he or anyone else carries the shroud seals, originally GM #3887425 and 3887426.

[Geoff Coenen (2473)]

Re: 66 390 HP w/A/C Question

Gentlemen, Scholars and SW’s:

Those two 1966 fan shroud seals 3887425 and 3887246 are certainly elusive in real life. As yet no one has ever requested these items. Occasionally however a desert pilgrim will appear. But, I remember when the Coelacanth was also very rare and doubtful.

From the method of attachment I would guess they were materially configured much the same as the A-frame dust seals if they were a fact. If anyone has an original, I know of a place where they have that exact same recycled rubber in 4x8 sheets.

Geoffrey

PS Carlisle Spaces F88 I will be autographing my new book "How to Retire with the Material Support of your Wife." Our new Company mascot is shown below.




Woody Junior

[Clem Zahrobsky (45134)]

Re: 66 390 HP w/A/C Question

hey doc i use those for target practice at my camp in northern PA sometimes 2 or 3 a day. they dig holes under the cabin and weaken the supports. we used to shoot more but the coyotes have help reduce the numbers. did you know they can climb trees as i have shot them out of my apple trees while they were eating my apples. they eat a apple like a person,the hold in their front paws and eat around the core and them throw the core away. if you want more i could box trap some and bring them to carlisle for you.

[Geoff Coenen (2473)]

Murderer, Killer, Butcher, Assassin, VH

Clem,
All you VH’s are ruthless killers. I hear they can be tamed so that they will eat from your hand. They live right under the concrete steps of my front porch. My house foundation is poured concrete too. Thus I think our cabin is secure for now. If we get too many holes in the yard, we may practice population control. Two weeks to the Carlisle events …
Geoffrey

[Clem Zahrobsky (45134)]

Re: Murderer, Killer, Butcher, Assassin, VH

doc,i also get them here at home but since i can not shoot in the boro i just live trap them and turn them loose out side of town. mrs clem says if i stop for a beer on the way back the groundhog beats me back. if you want to live trap they love red tomatos or apples. the young ones are good eating. see you at carlisle fellow VH

[Mike McCagh (14)]

Re: Murderer, Killer, Butcher, Assassin, VH

Clem: agree that "whiostle pigs", as we call them in westerm maryland, are real good eats but i usually stop by the l;ocal bar for a few brewskies before coming home for the woodchuck meal.mike

[Loren Lundberg (912)]

Is the bus coming to Carlisle??? *NM*

[Mike McCagh (14)]

Re: Is the bus coming to Carlisle???

loren: space at corvettes at carlisle at a premium and we can't park a motorhome, much less an ex-Greyhound 56 gmc bus so it won't be there. i'll be camping under the stars in the MAC tent. The Nascar tracks still welcome the old bus --we've infamous for the signs we paste to the bus, ie, Free Mamograms, Free Viagra performance verifications, Free Pelvics. Some of the guys that go to the races have way too much testosterone when they leave home. I, on the other hand, sleep at the foot of the cross and "father" the young guns. regards, mike

[Joe Lucia (12484)]

Re: 66 390 HP w/A/C Question

Geoffrey-----

You bring up an interesting point. I now wonder about these 3887425 and 3887426 seals. The parts definitely did exist, but I wonder how many, if any, were actually installed. Several things:

1) the fact that these seals never entered GM SERVICE gives rise to the real question that they were never actually used. This is not too definitve, though, since MANY of these shroud/radiator support seals used in PRODUCTION over the years were never available in SERVICE. However, most of the 66-67 Corvette seals were so-available with the notable exception of these;

2) these seals were called out in the original (or shortly thereafter) AIM sheet. The fact that they continued to be included on the revision issued so late in the year (6-8-66) would indicate that Chevrolet was "serious" about them. If they had been deleted from PRODUCTION, I would have expected that this late revision would have picked that up, especially since the page was "redesigned and redrawn";

3) the fact that the seals were deleted for 1967 PRODUCTION would, conversely, indicate that Chevrolet was not too serious about this item and, at least by 1967, decided that they should be deleted from the assembly.

As far as configuration goes, I always thought that these seals were similar in GENERAL configuration to the forward shroud-to-radiator seal used for 68-72 with small block and steel radiator shroud, but were shorter, molded sections to conform to the configuration of the specific big block and small block shrouds used for 1966.

It would be, indeed, interesting to hear from folks with original 1966 A/C cars. If the shroud is original to the car, it should show, at least, some vestige of the seal's former presence. The staple holes, for instance, should never "heal" if the seal "goes away". If we're lucky, there may even be an original seal left to document the configuration of.

[Loren Lundberg (912)]

Re: 66 390 HP w/A/C Question

The original shroud on this 66 BB is STILL on the shroud - His problem was with the radiator support seals, and the "revised" drawing. I''ll try to remember to take the camera over and shoot a picture.

[Joe Lucia (12484)]

Re: 66 390 HP w/A/C Question

Loren-----

That would be VERY interesting. The area in question, of course, is the forward, lower edge of the shroud. That's where these "enigmatic" seals were supposed to have been installed.