289 small water pump pulley

Woody3882

Member
Jun 19, 2018
66
9
18
70
Bradenton Fl 34212
65 Mustang 289 for some time now I have been having a problem with my single groove water pump pulley rubbing against the crank pulley. The crank pulley is after market and was changed because I installed air conditioning in the car. I just found out that the 65/289 had two different size single groove water pump pulleys. One was a smaller size 5.875" and the larger is the most common 6.12" the size of the pulley was determined by the way the motor was set up.
I am trying to find a part number or locate a smaller size single groove pulley with the measurement of 5.875" I have tried several internet outlets to no avail. I would greatly appreciate it if some on could locate one for me or the part number. If some one has one out in the junk pile that works also.
Thanks I appreciate any help one can give

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Woody3882

Member
Jun 19, 2018
66
9
18
70
Bradenton Fl 34212
65 Mustang 289 for some time now I have been having a problem with my single groove water pump pulley rubbing against the crank pulley. The crank pulley is after market and was changed because I installed air conditioning in the car. I just found out that the 65/289 had two different size single groove water pump pulleys. One was a smaller size 5.875" and the larger is the most common 6.12" the size of the pulley was determined by the way the motor was set up.
I am trying to find a part number or locate a smaller size single groove pulley with the measurement of 5.875" I have tried several internet outlets to no avail. I would greatly appreciate it if some on could locate one for me or the part number. If some one has one out in the junk pile that works also.
Thanks I appreciate any help one can give

[email protected]
I found the answer to my own question so I figured it might help someone else out: A 289 without air has a single groove water pump pulley. Once you add the air it require a smaller size 2 groove pulley . There is only 1/8" of a difference but it will scrape against the crank pulley. I don't know why they made it that way, but if you add a/c you have to change the water pump pulley to a smaller size or grind down an eight of an inch on the stock pulley.
 
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Carters

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Aug 6, 2021
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Arkansas
Thank you for the information you posted. I ran into the same problem this afternoon. I installed a new AC system in my ‘65 convertible. It never had AC before. I drove it over to my mechanic to have him charge the system but it made a horrible noise. I thought it was the fan hitting the shroud. It was actually the pulleys rubbing against each other. Long story short, I ordered a 5.85” water pump pulley. I’m glad I came across your post because it confirms what I learned today.
 

Woody3882

Member
Jun 19, 2018
66
9
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70
Bradenton Fl 34212
I am glad I was able to help. Another way around the problem is to use the double pulley that came with your A/C system. I know what you are thinking, I went through the same thing. a single was on there. But the double is better, one pulley for the power steering and water pump and the other pulley for the alternator and the water pump. This way is safer because you have two pulleys on the water pump in case you lost one of the belts. you might have to resize your belts but that is easy enough. Also I just put in a Spal 16" electric fan with the aluminum radiator. Works great but regardless of what you are told, you can not put a shroud on the 65 due to lack of space. The 16" fan covers so much room that a shroud is not needed ( I found that Spal fans are the way to go )
If you need any more help let me know and i will call you.
Best of luck
Woody
 

Woody3882

Member
Jun 19, 2018
66
9
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70
Bradenton Fl 34212
On the 65 Mustang 289 you do not have enough room to put in a shroud and electric fan. Not enough room.
I have seen some put flat sheet aluminum against the aluminum radiator fins, but in order to have a shroud properly work you need an air flow space between the radiator fins and the shroud. on the 65 if you use a 16" fan without a shroud it covers enough of the radiator to gets great temperature results
 
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