1970-1972 454 w/AC fan shroud

[D S.]

(From a 1970 Corvette LS-5 owner, a question I can't answer.)
Question on the fan shrouds. One number I was told is 3956119 for '70-'72 BB (exc. C.A.C., HD Radiator) and the other is 3974015 for '70-'72 BB with C.A.C.
What is C.A.C. and since mine is a BB with AC which one? Is 3974015 the extension?

Thanks,
Scott Sims
Texas Chapter

[Mike E.]

Re: 1970-1972 454 w/AC fan shroud

CAC is air conditioning. (Also known as C-60 in the AIM)

[Joe L.]

Re: 1970-1972 454 w/AC fan shroud

(From a 1970 Corvette LS-5 owner, a question I can't answer.)
Question on the fan shrouds. One number I was told is 3956119 for '70-'72 BB (exc. C.A.C., HD Radiator) and the other is 3974015 for '70-'72 BB with C.A.C.
What is C.A.C. and since mine is a BB with AC which one? Is 3974015 the extension?

Thanks,
Scott Sims
Texas Chapter

Scott-----

GM #3974015 was a FAN SHROUD; it was not an extension. It may have been used for all VERY early 1970 with LS-5. Thereafter, I believe it was used through 1972 for LS-5 with C-60. I'm not 100% sure about this, though. 1969-72 big block with copper brass radiator and WITHOUT C-60 used shroud GM #3956119.

The GM #3974015 was discontinued form SERVICE in December, 1973 and replaced by the GM #331869 which was the 1973 PRODUCTION shroud for LS-4 with C-60 applications.

Just how the GM #3956119 shroud differed from the 3974015 I do not know.

[D S.]

Re: 1970-1972 454 w/AC fan shroud

Thanks, Mike and Joe.

[D S.]

Re: 1970-1972 454 w/AC fan shroud

On my '70 LS-5 with factory AC I can't visually find a part number on the fan shroud but I believe it to be original. Could the BB fan shroud with AC be PN 3956109?

[Joe L.]

Re: 1970-1972 454 w/AC fan shroud

On my '70 LS-5 with factory AC I can't visually find a part number on the fan shroud but I believe it to be original. Could the BB fan shroud with AC be PN 3956109?

Scott-----


No, GM #3956109 is the 1969-72 Corvette small block with copper/brass radiator fan shroud. It was never used for a big block.

[Joseph M.]

Re: 1970-1972 454 w/AC fan shroud

Joe was correct. My early Jan 70 LS 5 non air car has fan shroud #3974015. It is light gray in color and made of some type of plastic material. My question is does this shroud have an extension and if so what is the part number?

[Joe L.]

Re: 1970-1972 454 w/AC fan shroud

Joe was correct. My early Jan 70 LS 5 non air car has fan shroud #3974015. It is light gray in color and made of some type of plastic material. My question is does this shroud have an extension and if so what is the part number?

Joe----


Yes, there was an extension used with it. It was GM #3974014.

[Joseph M.]

Re: 1970-1972 454 w/AC fan shroud

I recently saw what the seller claimed is a 70-72 NOS BB extension #3956089. Is this a GM replacement part for 3974014? If not what is it used for?

[Joe L.]

Re: 1970-1972 454 w/AC fan shroud

I recently saw what the seller claimed is a 70-72 NOS BB extension #3956089. Is this a GM replacement part for 3974014? If not what is it used for?

Joe-----



GM #3956089 is an extension used with shroud GM #3956119. This combination was used for most 1969 big blocks. It was also used for most later 1970-72 big blocks except those with C-60.

As far as I can tell, the GM #3974014 extension was used for early 1970 big blocks without C-60 and in combination with shroud GM #3974015. It was also used for 1970-72 big blocks with C-60 and in combination with either the 3956119 or 3974015 shrouds.

GM #3956089 was never supercessive to GM #3974014. GM #3956089 was discontinued without supercession in July, 1983 and GM #3974014 was superceded by GM #336152 in August, 1973. The latter piece was discontinued without supercession in May, 1990.

[Joseph M.]

Re: 1970-1972 454 w/AC fan shroud

Are there any sources for #3974014? Is Doc Rebuilds extension a good match? Lastly, any ideas on the headmark and finish for the bolts used to attach the extension?

[Jack H.]

Re: 1970-1972 454 w/AC fan shroud

It's pretty common for prior owners/mechanics to have discarded the fan shroud extension. At first, it looks like a clever designer inspired 'trap door' method for pulling the fan shroud without removing the hood, taking off the fan/fan clutch and/or standing the radiator upright.

But, as soon as one tries, they find that's NOT the purpose of the extension! So, it got discarded during re-assy...

My experience (A/C equipped '71 SB) is that the reproduction extensions 'may' fit and align with the reproduction fan shrouds, but the part didn't fit worth a darn on my factory original '109 shroud...

I had to make cuts, sand excess material off, and essentially 'rework' the piece to get it to shoe horn in...