73 LS4 fan shroud

[William M.]

My 73 LS4 w/AC was built 4/3/73. Technical Information Manual & Judging Guide says I should have a fan shroud extension part # 336152, but does not indicate what part # should be on the fan shroud itself.
The fan shroud on my car is part # 331869. In searching the archives, I found a post stating that this is a service replacement which came out in December 1973 to replace part # 3974015.
Is this true? If so, what deduction do I get in judging?

[Joe L.]

Re: 73 LS4 fan shroud

My 73 LS4 w/AC was built 4/3/73. Technical Information Manual & Judging Guide says I should have a fan shroud extension part # 336152, but does not indicate what part # should be on the fan shroud itself.
The fan shroud on my car is part # 331869. In searching the archives, I found a post stating that this is a service replacement which came out in December 1973 to replace part # 3974015.
Is this true? If so, what deduction do I get in judging?

William----


The GM #331869 fan shroud definitely did replace the GM #3974015 for SERVICE in December, 1973. However, that does not mean that it "came out" at that time. The 3974015 was the 1970-72 454 with C-60 fan shroud. However, I don't THINK that the 3974015 was used for 1973 with LS-4 and C-60 applications. It's possible that it was used for at least part of the year but, somehow, I don't think so.

I think that the 331869 was used in PRODUCTION for some, most, or all 1973 applications. With a a small block application it was used in conjunction with extension GM #331870 and with a big block it was used in conjunction with extension GM #336152.

I realize that the above is contrary to the AIM and I defer to to others with contrary empirical information. However, what I've described is what I believe to be the case at the moment.

By the way, if one were to find a GM #331869 on any 1970-72 LS-5 with C-60, it would definitely be a SERVICE part for those applications. For 1973 with LS-4, I think it's PRODUCTION.

[Harmon C.]

Re: 73 LS4 fan shroud

William
The 869 is the correct shroud for your car the other part of the story is I don't think an extension was used. I owned a 454 73 and it did not have the 336152 extension and I don't remember ever seeing one on a 73 but I have not seen all of them made.

[Todd L.]

Re: 73 LS4 fan shroud

William,

According to the 1973-74 Corvette Technical Information Manual & Judging Guide:
pg. 80
Radiator Shroud & Extensions
In 1973 a single fan shroud is used with different extensions for LS4 and L48/L82's. The L48/L82 shroud has an extension of approximately 2 inches, and has a part number of 331870. The LS4 fan shroud extension is much shorter, and has a part number of 336152. In 1973, the shroud has two(2) bolts attaching it to the radiator support by a single bracket at the top center of the radiator.
Hope this helps.

Todd

[Harmon C.]

Re: 73 LS4 fan shroud

The infomation is perfect for a small block. The assembly manual shows the extension and it is a half circle that fits only on the bottom but I'm not sure they were installed as I have not seen a car with one on that I know of.

[Todd L.]

Re: 73 LS4 fan shroud

Being new to the NCRS, how would the shroud be judged? I thought the Technical Information Manual & Judging Guide was the definitive source for ensuring your car is correct. I have a 74 BB with A/C but the extension is missing. I have been looking for this part because the guide states it should be there. Do I need it or not, and if not what if a judge says I do, what do I show as a reference to state my case?

Judges?


Todd

[Joe L.]

Re: 73 LS4 fan shroud

Being new to the NCRS, how would the shroud be judged? I thought the Technical Information Manual & Judging Guide was the definitive source for ensuring your car is correct. I have a 74 BB with A/C but the extension is missing. I have been looking for this part because the guide states it should be there. Do I need it or not, and if not what if a judge says I do, what do I show as a reference to state my case?

Judges?


Todd

Todd-----


I can't say, for sure, if the GM #336152 extension was ever used. However, I can tell you, for sure, that it did exist. It was available in SERVICE until August, 1990. Plus, somewhere around here I've got an NOS example [not for sale]. So, on the basis of those two pieces of evidence, there's no doubt it did exist.

Beyond that, it's a late 1972-released part, so it could not have been ORIGINALLY used on 1972 or earlier models. GM says it was not used after 1974 and I have no reason to believe it was, either, since it was a big block extension and big blocks ceased to exist in Corvettes after 1974.

All the above pretty much limits its application to 73 and/or 74 big blocks.

[Michael W.]

Re: 73 LS4 fan shroud

I thought the Technical Information Manual & Judging Guide was the definitive source for ensuring your car is correct.

Far from it. Like government, it ain't perfect but it's the best we got. The guides are constantly being updated as new information comes to light.

If you believe that a judging call is incorrect, there is a procedure that keeps everybody on friendly terms if followed correctly. Advise the judge that you disagree and provide substantiation for your point. If required advise the judging chairman and/or the team leader if present.

Don't expect to win your point just because you can out-talk the judge. In this case you might want to print off this string, there's not many people that know 73's better than Lyle.

[Todd L.]

Re: 73 LS4 fan shroud

I guess what I don't understand, is that the guide describes the extension, it gives a part number, and looking at my shroud the mounting points are there. I would like to make the car correct, would I or a 73 owner be wrong having the extension on it? I know it is probably a mute point, I just like to understand.

[Joe L.]

Re: 73 LS4 fan shroud

Far from it. Like government, it ain't perfect but it's the best we got. The guides are constantly being updated as new information comes to light.

If you believe that a judging call is incorrect, there is a procedure that keeps everybody on friendly terms if followed correctly. Advise the judge that you disagree and provide substantiation for your point. If required advise the judging chairman and/or the team leader if present.

Don't expect to win your point just because you can out-talk the judge. In this case you might want to print off this string, there's not many people that know 73's better than Lyle.

Mike-----


.....now Mike, don't go insulting the judging guides by in any way comparing them to the government. I don't necessarily mind constructive criticism of the JG's but this is a LOW BLOW!

[Harmon C.]

Re: 73 LS4 fan shroud

I guess what I don't understand, is that the guide describes the extension, it gives a part number, and looking at my shroud the mounting points are there. I would like to make the car correct, would I or a 73 owner be wrong having the extension on it? I know it is probably a mute point, I just like to understand.

When the manual was first done the aim was used to help write the manual and a survey was done of people with 73's to fill out an information form and the manual was printed and the extension on 454's probably was not on the survey. I can tell you not that many 454's have been judged at regionals so we have not seen many. The bottom of the shroud extension fits very tight to the frame on small blocks. If you had the extension for your big block I'm sure it would be very hard to install.
If some one has a 454 with the extension I would like to see a picture.
The mounting points are their on you car because all small and big blocks used the same shroud.

[Terry M.]

Re: 73 LS4 fan shroud

Hey Joe -- it IS an election year both above and below the border. The Northern border that is. Anything goes in an election year.

[William M.]

Re: 73 LS4 fan shroud

Good news, sounds like 331869 is the correct shroud for my 73.
Note that the JG talks about the 73 shroud, but doesn't indicate a part # . In the next paragraph, it does provide the part # for the 74 shroud, 339175. Sounds like a revision to the guide is in order.
Thanks to all.

[Harmon C.]

Re: 73 LS4 fan shroud

The correct 73 shroud is 331869 and the 339175 for 1974 is a replacement for the 869 and will fit.

[Todd L.]

Re: 73 LS4 fan shroud

Thanks for the info, hopefully in a few years there will be a 74 to be judged. I am learning there are a lot of one off items that will be my challenge, such as a diverter valve, BB air cleaner ring, and the water inlet. It is a treasure hunt. talking to a guy here in Denver, he was telling me how he threw away all the before mentioned items a few years back. It just breaks my heart.

Thanks for being here.

Todd