74 BB Eaton Fan Clutch to Water Pump - Bolts or Studs?

[Victor S.]

Good day all -

Trying to determine if the original fan clutch on the BB's were installed to the water pump via threaded studs or bolts?

The 73/74 Judging guide states 350's were attached with studs and the 454's used bolts - but my 454 has the original correct dated fan clutch that appears to have never been removed and it is attached to the water pump with threaded studs.

Looking for confirmation from the experts. Thank you.

[Joe L.]

Re: 74 BB Eaton Fan Clutch to Water Pump - Bolts or Studs?

Good day all -

Trying to determine if the original fan clutch on the BB's were installed to the water pump via threaded studs or bolts?

The 73/74 Judging guide states 350's were attached with studs and the 454's used bolts - but my 454 has the original correct dated fan clutch that appears to have never been removed and it is attached to the water pump with threaded studs.

Looking for confirmation from the experts. Thank you.

Victor------


Studs were used for fan clutch-to-waterpump hub for all engines in 1974. Of course, many of these may have ended up being bolts after waterpumps and/or fan clutches were field-replaced.

[Jimmy P.]

Re: 74 BB Eaton Fan Clutch to Water Pump - Bolts or Studs?

Victor,
Looking at the paragraph in the 73-74 TIM&JG on page 158 I can see why you were confused. As written it does lead one to think that LS4’s used bolts to mount the clutch to the pump. Joe is correct, that all clutches in 74 were attached to the water pumps with the studs. Actually the text should have read that in ‘ 74 there was a change where bolts were used to attach the FAN TO THE CLUTCH, a change from the earlier use of the studs, nuts and washers. (74 AIM UPC 6K Sheet 2 Changes made 7-18-73). We found this to be true on both the 74 LS4 and 74 L82 (why we mentioned seeing this on 350’s too. I’ve made some notes in my manual to revise this paragraph to clarify in a future revision. IIRC, during the revision our team discussed the fan clutch (variations) and different broadcast codes to great length. You’ll note we used the words “exceptions have been seen”in the last sentence. Plus we added a footnote #19 on the previous page.
I’ve attached a couple photos as examples from my files. First one is from a June built 74 LS4. The second from a June 5th built 74 L82. Note the bolts attaching the fan to the clutch. (not mounting the clutch to the water pump! )
Glad you posted your question. Made me go back through everything to research it!

[Tom R.]

Re: 74 BB Eaton Fan Clutch to Water Pump - Bolts or Studs?

Nice work JP!

[Mark E.]

Re: 74 BB Eaton Fan Clutch to Water Pump - Bolts or Studs?

Jimmy,

It's interesting your second photo shows lock washers while the first does not. Is one more typical?

[Jimmy P.]

Re: 74 BB Eaton Fan Clutch to Water Pump - Bolts or Studs?

Jimmy,

It's interesting your second photo shows lock washers while the first does not. Is one more typical?

Mark,
I’m going out on a limb here but I think the most common practice would be to have the lock washer installed. Looking back through all the photos I have when we were working on the 73-74 revision this is the only example without the lock washers in that location (the fan clutch to water pump nuts) you are asking about. I’m guessing the nuts may have been removed at some point and then installed minus the lock washers. Note the different amount of threads showing on the studs, and the marks (nicks) on the nuts.They would pretty much all look the same when factory installed. Wouldn’t you think?

[Joe L.]

Re: 74 BB Eaton Fan Clutch to Water Pump - Bolts or Studs?

Mark,
I’m going out on a limb here but I think the most common practice would be to have the lock washer installed. Looking back through all the photos I have when we were working on the 73-74 revision this is the only example without the lock washers in that location. I was more focused on showing the bolts fastening the fan to the clutch examples. I’m guessing the nuts may have been removed at some point and then installed minus the lock washers. Note the different amount of threads showing on the studs, and the marks (nicks) on the nuts.They would pretty much all look the same when factory installed. Wouldn’t you think?

Jimmy------


Split lockwashers were used in conjunction with the studs and nuts on the fan clutch-to-waterpump hub. Lockwashers were not used on the fan clutch-to-fan bolts because those bolts are flanged head. Lockwashers are virtually never used in conjunction with flanged head bolts even if the bolt flanges are non-serrated.

[Jimmy P.]

Re: 74 BB Eaton Fan Clutch to Water Pump - Bolts or Studs?

Jimmy------


Split lockwashers were used in conjunction with the studs and nuts on the fan clutch-to-waterpump hub. Lockwashers were not used on the fan clutch-to-fan bolts because those bolts are flanged head. Lockwashers are virtually never used in conjunction with flanged head bolts even if the bolt flanges are non-serrated.

Yeah Joe thanks, those were the bolts/ washers Mark asked about above. Not the bolts connecting the fan to the clutch. I edited my post above to clarify a bit more. Always a wealth of info! All good!