C3 fan clutch application and date question

[Tom L.]

I recently purchased a fan clutch that came off of a late '72 LS5 without A/C. The hole patterns match to my 7 blade fan (I have A/C) but am wondering if it's the correct application for my car before I move forward with getting it into shape.

The numbers on the clutch hub are: C1672SC. I don't have the new JG but my older one doesn't indicate that there should be a "C" in front. And from what I read the 1672 part of it means it's from the 167th day of 1972, Is that correct? Thanks!!

[Joe L.]

Re: C3 fan clutch application and date question

I recently purchased a fan clutch that came off of a late '72 LS5 without A/C. The hole patterns match to my 7 blade fan (I have A/C) but am wondering if it's the correct application for my car before I move forward with getting it into shape.

The numbers on the clutch hub are: C1672SC. I don't have the new JG but my older one doesn't indicate that there should be a "C" in front. And from what I read the 1672 part of it means it's from the 167th day of 1972, Is that correct? Thanks!!

Tom------


I can't speak to the date code. The format is not that which I'm familiar with but Sweitzer may have changed the format by 1972. If so, it's likely a julian code, as you surmise.

All 1972 Corvettes, small block or big block, C-60 or not, used the same fan clutch. This was GM #3991426. It was a "dog dish" style clutch with Sweitzer-style "bi-metallic" thermostat. It was designed for 3-1/4" bolt circle fan attachment and 2-5/8" bolt circle hub with a 3/4" pilot hole.

[Tom L.]

Re: C3 fan clutch application and date question

Tanks Joe, I'll post a pic when I get a chance, probably should have done that.

On another note, it feels real tight and there doesn't seem to be leaks. I'd say that the worst part of the piece is the oxidized finish on the aluminum. If I were to use it as is there a way to, within reason, bring the aluminum back to life without a restoration of the piece? Thanks!!