1975 A I R pump pulley

[Lynn S.]

In the process of confirming through the 1975-1977 NCRS Technical Info Manual and Judging Guide I have run into a roadblock. The manual states the pulleys have a part number (3917234). When I search various sites this is for earlier Chevy vehicles including 1968-1969 327 & 350 Corvettes, but not for a '75 L-48 motor car. I next went to the official Chevy Parts Catalogue. It lists the correct number for a '75 L-48 is (3932458). What's a man to do and not have to take a hit when my car is completed and ready for judging? Thanks in advance. Lynn

[Patrick H.]

Re: 1975 A I R pump pulley

Lynn,

I assume that the AIR pump and pulley are missing from your car?

Patrick

[Lynn S.]

Re: 1975 A I R pump pulley

Yes. As was the case many times over, it was long gone when I bought the car in a fully disassembled condition. I have found the correct pump, diverter etc for my L48 motor car. But the pulley that came with the pump I purchased has the incorrect number per the NCRS Judging Guide. Hence my question on what is the correct numbered part since the Corvette Parts Manual list a different number for L48 motors. The number in the parts manual is for an L82 in 75 plus other engine configurations dating back to 1968 and 69 - 327 & 350 engines. By the way, I recently purchased engine sticker codes from you. Thanks for your reply.

[Joe L.]

Re: 1975 A I R pump pulley

Yes. As was the case many times over, it was long gone when I bought the car in a fully disassembled condition. I have found the correct pump, diverter etc for my L48 motor car. But the pulley that came with the pump I purchased has the incorrect number per the NCRS Judging Guide. Hence my question on what is the correct numbered part since the Corvette Parts Manual list a different number for L48 motors. The number in the parts manual is for an L82 in 75 plus other engine configurations dating back to 1968 and 69 - 327 & 350 engines. By the way, I recently purchased engine sticker codes from you. Thanks for your reply.

Lynn------


Very early 1975 except cars with C-60 may have used pulley GM #3917234. Later, except C-60, used GM #3932458.

All with C-60 used pulley GM #3927116.

[Lynn S.]

Re: 1975 A I R pump pulley

Joe, please help me a little more. What is C-60? Is that A/C, P/S or some other option. My 75 has A/C, P/S and P/B. Thanks for your reply.

[Joe L.]

Re: 1975 A I R pump pulley

Joe, please help me a little more. What is C-60? Is that A/C, P/S or some other option. My 75 has A/C, P/S and P/B. Thanks for your reply.

Lynn------


C-60= air conditioning ("A/C")

This means that your car originally used the GM #3927116 AIR pulley. That makes you lucky because that pulley is the least expensive to obtain. The others that I mentioned can be quite pricey, to say the least. All of the pulleys I previously mentioned are long-since GM discontinued and can only be found NOS, used, or reproduction.

[Lynn S.]

Re: 1975 A I R pump pulley

Thanks for all your help.

[James G.]

Re: 1975 A I R pump pulley

I've got a few of the 116's you can have your choice if you pay the ride to you... contact me.

[Lynn S.]

Re: 1975 A I R pump pulley

I've got a few of the 116's you can have your choice if you pay the ride to you... contact me.

James, Thanks for your info regarding the AIR pulley. We just returned from an extended trip and my first chance to write. What would be your best price for a pulley with just the 3927116 number on it. I have found out that some have this number followed by AU of AC. Just the number without the letter suffix? Thanks for your input.

[Lynn S.]

Re: 1975 A I R pump pulley

Lynn------


C-60= air conditioning ("A/C")

This means that your car originally used the GM #3927116 AIR pulley. That makes you lucky because that pulley is the least expensive to obtain. The others that I mentioned can be quite pricey, to say the least. All of the pulleys I previously mentioned are long-since GM discontinued and can only be found NOS, used, or reproduction.

Next question: I am finding pulleys with the 3927116, some with the ...116 followed by AU and some followed with AC. Which is the correct part number I need for my set-up with air conditioning? Thanks for your help.

[Lynn S.]

Re: 1975 A I R pump pulley

I have seen two versions of the xxxx116 pulley. One has the number stamped on the side with the rounded groove edge to the side of the stamping and one with the xxx116 stamped on the side of the pulley with the cut or non-rounded side of the pulley groove. Is there a specific side that of the belt groove upper portion that needs to face the front of the engine? With two pulleys that have the same xxx116 but on different sides, which is correct for NCRS or does it matter as long as the number faces tha front of the car/radiator?
Thanks

[Lynn S.]

Re: 1975 A I R pump pulley

I found the answer to my own question. Page 283 of the A I M shows the AIR pump with two different pulley illustrations. View A "C-60 states RAW EDGE OF PULLEY MUST BE INSTALLED FORWARD". And the C-60 pulley has GM part number 3927116. Below view A is a second illustration (evidently NON-C 60) with part number 3932458 stating "RAE EDGE OF PULLEY MUST INSTALL REARWARD". My car is a C-60 car, therefore the RAW edge is installed facing forward and has the part number ending in 116 on the correct forward side also.
Thanks for your replies.

[Tom R.]

Re: 1975 A I R pump pulley

Well this certainly gets interesting!

I found the answer to my own question. Page 283 of the A I M shows the AIR pump with two different pulley illustrations. View A "C-60 states RAW EDGE OF PULLEY MUST BE INSTALLED FORWARD". And the C-60 pulley has GM part number 3927116. Below view A is a second illustration (evidently NON-C 60) with part number 3932458 stating "RAW EDGE OF PULLEY MUST INSTALL REARWARD". My car is a C-60 car, therefore the RAW edge is installed facing forward and has the part number ending in 116 on the correct forward side also.

The current draft for the chassis section (3rd edition-yet to be released for publication) lists the 3917234 A.I.R. pulley, but its an item we did not question. Apparently, we should have from what I see above and your (Skipper) nice research. I've asked a few of our car survey owners (early cars) to take a look at their A.I.R. pulley and learn what P/N's they show.

1. Can I get a picture of the 3927116 pulley?
2. Why does note 2 clarify the edge of the pulley be installed rearward when the application is directed to a non-C60 installation (or the 3932458 application)?

Lynn, my point is either both A.I.R. pullies have a raw edge but each calls out a different belt and a different installation...most interesting! Note #2 should not apply to your application, which you note (its for the non-C60) application. If you look at the belt schematic, you see the A.I.R mounts above the water pump and must require some extra depth to align with the water pump pulley.

Lynn, your conclusion is on point for your configuration...L48, C60 with P/S and P/B. I'm curious if our early 75 cars show the 234 or 458 pulley.

1975-77 _belt schematic_01Mar21.pdf

[James G.]

Re: 1975 A I R pump pulley

DAVID SOKOLOWSKI in California has hundreds 1974-82 for sale #258 DRIVELINE , page 32. Phone 310-329-5334.

[Lynn S.]

Re: 1975 A I R pump pulley

James, I already have the correct pulley for my car and configuration/application. Thanks for offering. My article and feedback I self submitted was well received by Tom Russo based on the follow-up research I have done the past several days. See Tom's reply from earlier today in reply to my self reply from yesterday.