C3 AIR Pump Pulley Quiz

[Tom R.]

What year AIR pump would you expect GM# 3932458 pulley to be bolted to? The letters are white and stamped onto the side of the pulley facing the radiator shroud.

Last time I did this I got an internal error from the server...

[Joe L.]

Re: C3 AIR Pump Pulley Quiz

Tom-----

I would say from late 1968 forward. I'm away from home right now so I can't determine the exact application.

[Tom R.]

Re: C3 AIR Pump Pulley Quiz

GM 3932458 is installed on a 78 pump with casting code 7817872 and date code 113081S. I had read somewhere that this pulley was unique to the early C3 years but that in later years...no stamps appeared on the pulley (78-79 manual). I have another I'm going to check...still on a 78.

[Joe L.]

Re: C3 AIR Pump Pulley Quiz

Tom-----

I'll check it when I get home. I'm sure it was used from about late 1968. However, it's still very possible that it was used into later C3's.

[Tom R.]

Re: C3 AIR Pump Pulley Quiz

MOst interesting because I think it will change some thinking on late model C3 tech team leader types...but then some are indifferent to the technical considerations for these years and therefore it becomes unremarkable.

[Terry M.]

Re: C3 AIR Pump Pulley Quiz

Tom I have judged a lot of 1968-1972 Corvettes with AIR pumps installed -- looked at many more. I have NEVER seen a pulley (AIR or otherwise) with white letters. I guess I am missing something there.
I have seen some in photos, where the photographer used chalk to enhance the numbers so they would be visible in the image.

[Tom R.]

Re: C3 AIR Pump Pulley Quiz

Terry:

Don't lose perspective of where this thread began...it's less about 68-72 AIR pump pulleys and stamping and more about 78-82 AIR pump pulleys and what's stamped on those units.

[Tom R.]

Re: 3932458 Photo

Here's image of pulley installed on a 78 AIR L82 pump

[Terry M.]

Re: C3 AIR Pump Pulley Quiz

Well then I can say for sure I would NOT expect to see that pulley on a 1968-1972. While it might be the same number, the earlier pulleys were stamped the old fashioned way -- steel onto steel making impressions in the metal of the pulley.

[Joe L.]

Re: C3 AIR Pump Pulley Quiz

Tom------

The GM #3932458 AIR pump pulley was first used for 1969 Corvettes with L-46. That is the only application I can find through 1974. However, it was later used for all 1975-79 Corvettes with AIR and C-60.

The 1969 version of the pulley had the part number stamped into the metal. However, sometime during the 75-79 period, it appears that the stamping method changed to a white ink stamping. Just when that occurred I have no idea. My guess would be in the 78-79 time frame. That's about the time when some part number emplacements changed to ink-based methods.

The change to ink-based stampings has absolutely nothing to do with the part number or otherwise configuration of the part or the functionality of the part.

[Terry M.]

Re: C3 AIR Pump Pulley Quiz

"The change to ink-based stampings has absolutely nothing to do with the part number or otherwise configuration of the part or the functionality of the part."

Ah, but those pesky judges will focus on the style of the numbers stamp and mark their deductions appropriately.

[Tom R.]

Re: In conclusion...

But than, late model C3 manuals were written with certain assumptions (the assumption being that it was done in 78-79 as previous model years) when the availability of data was scarce...the pulley is such a component. The 78-79 manual reports "no number" which I believe was a carry over from the 75-77 application of the pulley. We now know that indeed these pulleys carried the part number but printed with white numbers.

So all those following this thread now have the knowledge to distinguish the nuances of numbering stamping on a 68-82 AIR pump GM# 3932458 pulley. Thank you both for filling the knowledge gaps.

[Terry M.]

Re: In conclusion...

Tom,

You will let the appropriate team leader in on what we all know so that the TIM&JG can be changed so that more than just those following this thread will also know, right?

[Tom R.]

Re: In conclusion...

I'll send him a link