71 SB fan clutch

[Robert P.]

I purchased a fan clutch from a gm dealer for my 71 LT1. They gave me a AC Delco 15-4317 GM no. 88961765. It fits on the water pump OK but the flange is about 1/4 in longer than the one on the engine.I have a SC looks to be origianl. Would anyone know if this is the right replacement? Thanks Bob

[Joe L.]

Re: 71 SB fan clutch

Bob-----

If you're after an original-configuration fan clutch, you won't be able to get one from GM or Delco. 1971 used a one-year-only fan clutch of GM #3991426. It was discontinued YEARS ago. For an original configuration clutch, your best bet is to have yours rebuilt by Fred Oliva or others.

As far as a functional replacement, the only GM-cataloged replacement for the 3991426 was the GM #14063640 and it's long gone, too. The Delco-cataloged replacement is GM #89000174, aka GM #15-80275. However, I would NOT use this fan clutch, at all. It's an aftermarket-type unit and a "cheapo".

The unit that your dealer sold you, GM #88961765, aka Delco #15-4317 is a replacement for many 76-79 Corvettes. Notwithstanding the difference you described, it should work perfectly for your application. I consider it to be a much higher quality unit than the above-referenced unit. I would use it without reservation for your application.

However, for a functional replacement that will outperform ANY other unit on the market, I'd use a GM #88961768, aka Delco #15-4950. This unit will have a configuration less like your original than the 15-4317. However, it will fit and function perfectly for you and IT WILL COOL. This is a heavy duty, Eaton-manufactured piece that is my favorite fan clutch of all time. This one will do the job in Death Valley in July. I know; I've "tested" it there then.

[Robert P.]

Re: 71 SB fan clutch

Thanks Joe, My plan is to have mine rebuilt. I just wanted to be sure after seeing the difference in the shaft length. I called a few local GM dealerships but nobody could help me. Thanks again for the info! Bob