Question on a 70 LT-1 fan clutch

[Steve F.]

I am searching for the right fan clutch for my 70 LT-1. Would this be the same as all other small block cars? Someone mentioned it may use a big block clutch although that would seem off as I believe they have a different shaft length?
Could someone tell me the differences between the fan clutch for a small block versus big block and if the LT-1 is the standard small block fan clutch or something different.

[Terry M.]

Re: Question on a 70 LT-1 fan clutch

Yes there is a difference in shaft length between the BB and SB fan clutch. I can not tell you how much or which is longer, but I am sure someone else will.

Most 1970 LT1s (and I believe the other years of LT1s as well) have Switcher (I am probably spelling that wrong) fan clutches. I can not prove all LT1s should have that brand however, but I believe that is the case from the LT1s I have seen. In addition to the letters SC on the clutch hub (where the date is), Switcher clutches have a flat plate on the front that senses temperature and controls clutch engagement. Eaton clutches have a circular spring on the front and usually have no visible date on them as installed.

OEM fan clutches of this period have straight fins on the back side, and often have a faint green spray mark on those fins. All OEM clutches have holes rather than slots for the attachment to the water pump hub.

[Steve F.]

Re: Question on a 70 LT-1 fan clutch

Thanks Terry, I also have a 70 Mulsanne Blue LT-1.
I should have said is it the same as other 70 fan clutch's as I know they changed in 71. I have two of the Schweitzer
later pieces but they are for the larger water pump and I don't want to use a reducing bushing. Lots for sale on ebay but all are big block.