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What is the correct fan clutch for a 71 LS-5? Is the correct fan clutch still available form GM? What is the part number for the fan clutch ? I don’t see any listed in the suppliers catalogs they go up to a 70 then skip 71 all together and have one for 72. Thanks
1971 used a one-year-only fan clutch, GM #3991426. It was discontinued a LONG time ago without supercession and is not reproduced. The clutch portion of the unit looks very similar to the GM #3937771 used for many 1968-69. However, the bolt patterns for both the hub and the fan mount were enlarged to the 1971+ spec. Also, the pilot hole was enlarged from 5/8" to 3/4".
I went through this a while ago and Joe gave me the following advise....(copied from the archives so you can search for the full thread)
He was right about the noise, but it does work!
Tom
Tom------
Yes, you are correct; 1971 used a one-year-only fan clutch. However, there are other clutches that will work just fine for you.
My recommendation is a GM #88961768 aka Delco #15-4950. This unit will be a direct bolt-on for your application. Its configuration is much different than the original, but that won't affect installation or functionality. In fact, in my opinion, this is ABSOLUTELY the best fan clutch out there. Folks with 1970 and older can't use it without substantial modifications and other parts changes. But, you're one of the lucky ones. For 1971 and later, it's a direct bolt-on.
It's somewhat more noisy than other units, especially in hot conditions, because it's pulling a lot more air. That comes in real handy in summer weather in traffic-----the extra noise will be "music to your ears". The predecessor of this unit (which was very similar to this one) was used on most 74-81 Corvettes with C-60 or heavy duty cooling systems.
After using this unit for awhile, you won't want to go back to your original. This unit will perform FAR better than your original did when it was NEW.
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