The Stovebolt Site Forums The Shop Area Engine Shop short shaft water pump woes

I made a new 235 water pump into a short shaft pump. I ordered the Ford pulley that Jerry recommends. That all worked out perfectly. But now I can't find a fan that will clear both the crankshaft pulley and the radiator. I bought an Allstar # ALL30104 fan. It just barely hit the crankshaft pulley. When I shimmed it out until it barely cleared the crankshaft pulley, then it hit the radiator. The fan is just too deep from front to back. It would be very easy to find a fan that would fit, if I could find a place where they showed detailed dimensions of them, but I can't. Can any of you point me to a place where I can research this? Or can one of you recommend a fan that will fit?

Mike, you working on the 40 half ton?
Take a look and see if you can move the radiator forwzrd a little...maybe a little modification?

I had the same problem and used a shorter blade flex fan on my 37. It worked good but in a slow moving parade the V8 engine ran a little warm.....in the end i had to go with an electric fan but I'm not original. Just tossing around something for thought.

This site shows the dimensions of flex fans you can buy.
https://flex-a-lite.com/belt-driven-fans.html

No, the 40 is fine. I'm sorry, I should have said that I'm working on the 53.

I’m not familiar with all the differences in your short shaft pump vs the one you can buy off the shelf.

I have the “off the shelf” pump in my 1951 and this is the fan Jim Carter recommends running with it.

https://oldchevytrucks.com/mee243.html

Works fine for me.

That's the stock fan, isn't it?

When it come to cooling engines (on any make or model), everyone thinks you have to replace the crankshaft driven fan on the water pump with a flex fan or a 5 or 6 or 7 blade fan, or an electric fan or whatever. In my experience, the manufacturer usually got it right with the original design. Those solid metal, offset 4 blade fans found on most engines of the 1950s do the job perfectly well.

agreed

Do you feel the cooling is sufficient even if it doesn't sit in the center of the radiator?

Mine is cooling well so far.

I respectfully disagree. When these trucks and cars were new, traffic was not what it is today. They were never designed to sit in the kind of traffic we have today or a parade on a really hot day. So when first designed, the four blade fan was more then adequate and frankly less expensive to install on the production line. .50 cents saved for each car or truck built over the course of say 1.2 million production is a $600,000 dollar savings. So GM was certainly trying to use the minimum necessary.

I recently installed a five blade fan from a 59 348 motor with AC on my 261 and the difference in air flow through the radiator is significant. I sat at idle in a line of vehicles leaving a show in Bowling Green KY a couple of weeks ago in 98 degree weather for a significant period and the motor never got beyond 185, a first in many many years. With the four blade fan, I would be just under 220 pretty quickly. Just going from the four blade to the five blade AC fan alone reduced the temp to a very manageable level. So my first hand experience tells me the additional blade is very helpful to keeping these motors cool for today's usage.

My stock 1950 AD can and does sit in rush hour traffic on a weekly basis in 90+ degree heat and never exceeds 185 degrees. I don't have overheating problems with my 1956 Cadillac under the same conditions, either. It too, has a 4 blade fan.

Does your truck still have the original 216 with the high position pump? If so, that’s not exactly the same situation. The fan would be very centered to the radiator in that scenario.

I have a late 235 in my 51 truck with the short shaft pump and 4 blade fan. This places the fan lower than center and isn’t optimal. It works for me, but on a very hot day while idling and stopped, the temp will creep up a bit.

I’ve never been stopped long enough to have a full blown overheat situation. I don’t know if it would get there or find its max temp somewhere below that.

I assume so. The engine is a 1951 216 and the radiator is a 1941 model.

Is the engine a 55 and up if it is you might have to find a smaller diameter fan. I use the water pump adapter of the 55 and up engines.

Jeff, I'm working on a 235 swap for the 216 in my '51 3100. Is the "water pump adapter" you mention the adapter that raises the pump higher on the 235 engine so t is centered on the older radiator? I'm weighing options of that adapter vs. just a short-shaft pump. Thanks!