I have a 79 F250 that I dropped a 74 LTD 460 into and I reused a fan clutch from the car. My question is that with my 7 blade fan the clutch isnt turning the fan hard enough. I guess Im explaining it correctly. I went to my local parts store and got a new replacement for the 74 LTD and its not only smaller in size but its also not doing a good enough job turning the fan and cooling the motor at idle. I went back and bought a fan clutch for a 79 F250 2wd truck and its much larger but it part that bolts to the water pump will not fit through the hole in my fan blade. Any suggestions? Im guessing I need a fan blade from a 79 truck.

 

What size radiator are you working with? Also, do you have a fan shroud on it? What do you mean isn't turning the fan hard enough? How do the pulley sizes of the fan clutches compare to what a truck would have?

 

By hard I guess I mean fast. It has the biggest 79 radiator approx. 19 1/4" x 26 1/4" x 3" thick. Its from a 79 camper special extra cooling with a 460 and AC even though now its in a 79 F250 4x4. Im pretty sure its 3 core and I have a trans cooler infront. Yes I do have a fan shroud. The fan clutch from the car is very thin about 1" thick and the one for a 79 F250 2wd is about 2" thick and bigger in diameter by about 1/2". The correct 79 F250 2wd fan clutch wont fit through the hole in a 74 ltd fan blade.

 

So what are the symptoms? Boiling over? Overheating? How's the thermostat? How's the radiator? What history do you have of this engine? Could you get a different water pump that will fit the fan clutch for the truck on that LTD 460? My 460 cools fine with AC blowing in the 105 degree summer heat. These trucks do not have very accurate guages you know. Maybe a bad sending unit?

 

go electric

 

Answer to your question Yes you need the fan blades for the 79 truck to fit that clutch they are bigger and have the correct size holes. The car blades won't fit the pickup clutch.