so i went to the junk yard and got a 5 blade (2 on bottom and 3 on top # 14077928) from a chevy van. my 7 blade got bent up pretty badly and didn't want to risk heating issues. it's for an '84 L69. you think this'll work? i also got the pully from it part #14023156 2 grooves. the center hole that goes over a stub is just a bit smaller and needs to be bored open a tad. what is the circumfrence of a regular H.O. pulley, or does it matter? thanks, joey .

 

Use your old pulley.

 

that's the prob....i can't find my old pulley. got lost during my move i guess. why do you recommend that? different sizes? have one for sale? lol

 

As long as the belts line up and the bolt pattern is correct, just bore it out and use it. For diameter, just make sure you have some amount of overdrive against the crank pulley. For example, if the crank pulley measures say, 7 3/4" and the waterpump pulley measures, say, 6", you are overdriven approx 29% (7.75" divided by 6" = 1.29 or approx 29% overdriven, which is about ideal). Beware of underdriven. It can cause overheating problems irregardless of the availability of underdriven setups for sale. Stewart Warner recommends 20 to 30% overdrive on waterpump for the most efficiency on a cooling system. Atleast make sure it's smaller than the crank pulley. Good luck!

 

BTW, alot of times the 5 blade fans are made with more pitch than the 7 blades and the staggerd pattern of the blades around the circle is to reduce noise. As long as the fan is the approximate same diameter as the old one, you should be fine. Make sure the blade clears your shroud by no more than 1 1/2" and that's pushing it from an efficiency stand point1" or slightly under is preferable.