[kenny k]

I put a 1972 mild 383 stroker motor in my 71 vet , my kids bought me a water pump from summit , any way I dropped the motor in and I noticed the shaft on the water pump is 5/8 and my cluch fan has a 3/4 inch hole I assembled it with the old fan ,I have it running got the over heating problem solved runs nice and cool under 180 degrees . My question ,is this dangerous ? Should I put on a flex fan that fits the 5/8 shaft on water pump? Or get a spacer that would fit in the hole of the clutch fan and around the water pump shaft.or replace the clutch part with one that fits the water pump shaft and attatch the stock fan.any ideas

 

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the Corvette is a short with a 3/4 pump shaft.. can you not exchange the pump for a Corvette style ? the purpose of the hole in the clutch flange is to assure perfect alignment.. if you have a bushing , use it.. the 4 bolts will center it pretty close.. I ve seen people run them that way for years, the fan turns far less rpm than the motor ,but if you run it hard , I wouldn t rely on the bolts ..does your water pump pulley line up properly with the other pulleys now? sometimes the non-Corvette pump is not exactly the same length shaft

 

[kenny k]

Fishslayer ,the pulleys line up ,it's a short pump. The motors all together in the car and running ,I'm to lazy to take her all a part ,I'm looking for another solution ,maybe remove the stock fan and go with a flex fan.Thanks k.k.

 

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Ah, I see......well, I run a Stainless Steel Flex Fan from Hayden on my Stroker .. have for years.. better cooling

 

[kenny k]

I found a bushing that will slide over the 5/8 water pump shaft and the O/D is 3/4 .Summit carries them. K.K.

 

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there you go.

 

[toobroketoretire]

Fishslayer ,the pulleys line up ,it's a short pump. The motors all together in the car and running ,I'm to lazy to take her all a part ,I'm looking for another solution ,maybe remove the stock fan and go with a flex fan.Thanks k.k.

After I bought my big-block '71 I found it had a 5/8" shaft water pump and 5/8" bore pulleys but had a 3/4" fan clutch. As the hub of my fan clutch had holes rather than slots it worked perfectly with no slop whatsoever. But I ended up putting the correct pump on it and enlarged the holes in the pulleys to 3/4" so now all is back to normal.

As a first choice it's certainly better to use the 3/4" shaft water pump, pulleys, and fan clutch but for street use it doesn't really matter as all of the cars used the smaller sizes without any trouble.