The Stovebolt Site Forums The Shop Area Engine Shop Water pump - short shaft or relocation plate?

I was planning to do a short shaft pump on my '59 235 but have been reconsidering the adaptor plate with older style pump. I'm pretty well up to speed on the details of each. Looking for insight from anyone who has done either. My main concern with the adaptor plate was drilling the block. Got a bunch of questions about each option:

Short shaft questions:

-Has anyone shortened their own stock pump? If so, can you provide any details or advice on how it's done?
-What pully is used? Can I find the pulley by itself? (for 3/8 belt)
-Would I reuse my stock '59 fan?
-Anyone have any overheating issues due to low fan location? (not centered in radiator)

Adaptor plate/older style pump questions:

-Have people had problems with blocks cracking due to drilling, or is that fake news?
-I have the larger diameter car balancer which they say should be changed for smaller diameter. Is this really necessary with taller (numerically lower) gearing/lower overall engine RPM?
-Can I use my stock '59 fan on the earlier pump with 3/8" pulley?

Ron

A short shaft pump places the fan WAY too low on the older trucks' radiator, which creates problems with fan blade length and airflow through the radiator. The relocation plate solves both problems very effectively. Drilling and tapping two holes is child's play- - - -even if the child's fingers are covered with band-aids! Yes, swap to the smaller balancer- - - -not necessarily for the diameter, as the pulley sheaves are the same size on both, but it makes it a lot easier to find the proper water pump with the wide fan belt. The high mount pump with the narrow belt is very hard to find, and expensive.
Jerry

Yes, you can have overheating issues with the pump/fan down low. Especially if you're driving slowly or in city traffic.

Shortening the shaft can be somewhat easier or a lot of work. To find out, you need to use a press to lift the hub up and look at the shaft. There were some pumps which used a stepped shaft...meaning you just pressed the hub on as far as it would go and it was automatically at the right spot when it bottomed against the step. Then there were some which had a straight shaft and you pressed those on using a spacer...you stopped pressing the hub when the hub just contacted the spacer. In my experience the stepped shaft are more common (because they were cheaper and faster to assemble) and you'll have to turn the shaft down to relocate the hub. If you have a lathe and if you can disassemble the pump, not a really bad job but otherwise no...not a good project at all and if you're not good with a metal lathe you can ruin it. The hub has to fit tightly. Friction is all that holds it to the shaft and you don't want it coming off.

Personally I got a short shaft pump and did away with the fan entirely in favor of a thermostatically adjustable Spal puller fan, a shroud and an alternator. After hearing a friend who ran a machine shop talk about spinning 5 random 235 fans I don't want one anywhere near my engine. They're too old and too many things could have happened to them. Only one was balanced fairly well, he said. According to him it wasn't just the weight part of balancing either. If one or more blades had been bent or damaged in some way even slightly or if it had cracked down near the center it would cause trouble. Back when a made in the USA pump cost $20 or so that wasn't so bad. Today you get some iffy made in who knows where water pumps and a short shaft type might cost over $200. I don't want a fan shaking it apart. Besides without that fan the engine will run more quietly. As for the short shaft pulley, I'm not certain where those can be had. Good luck!

It's not doing the drilling/tapping that concerns me, it's some of the comments I read elsewhere about blocks cracking, etc. I have no idea whether such claims are true or not. Was hoping someone could shed some light on that.

The other thought I had regarding cooling was it looks like the adaptor plate blocks off much of the large hole on the front of the block. Seems that would cut down on coolant flow versus having the "correct" stock pump installed?

Trying to maintain a stock look, so hoping to not go to electric fan. May even stick with 6V, but haven't decided for sure on that yet.

Blocks are being cracked by ham-handed idiots who overtighten the bolts. There's a small gap between the pump housing and the block where the holes are tapped that should be filled with a flat washer, filed or ground to accommodate the slight taper in that area and held into place by J-B Weld or epoxy. Far too many people want an "easy button" that eliminates any necessity to apply even a smidgen of common sense to a modification. "Ignorance can be fixed- - - - -stupid is forever!"
Jerry

I wasn't aware there were different types. Just so I understand this correctly, you're saying I have to press the hub a bit as though I'm removing it, and then look to see if there is a step where it was located? Sounds easy enough.

I'd like to just make my own short shaft pump and try that first if I can. If it overheats, then think about the adapter plate. Beats buying a short shaft pump, spending the money, and then ditching it later.

Yes, it sounds like you know what you're doing...Support the hub with a couple of pieces of thick metal plate or whatever you can get behind it and then press downward on the shaft with the hub supported. If you move the hub toward the front of the shaft by 1/8 inch or so you will either see a machined step or nothing but the shaft. If you see a machined step, then you have to remove the hub, disassemble the pump, take the shaft and chuck it into a lathe and carefully turn the shaft down to match the small part of the shaft and put all back together again. (that's not the easy way but go slowly and carefully) Please be really careful when you remove the impeller from the shaft. If your pump is old and has rusted there the impeller and the shaft can sort of become "as one" and they may not want to separate. I've seen people crack impellers trying to remove them.

If you see no machined step, then you can support the shaft on the back side (the center...where it goes into the impeller) and carefully press the hub down as far as you need to make a short shaft pump and cut off the excess. (that's the easy way and it usually doesn't take that much effort if the shaft isn't rusty) Just be really certain to support the shaft and not the impeller when you start pressing down on the hub and go slowly. Maybe use a socket the same size as the shaft. It should sit flat enough. Good luck.

I wasn’t confident enough to take on the adapter plate when I first got my truck. Went the short shaft route. It works fine. I’m sure the proper pump in the proper spot would be better. Someday I will do that.

If I’m stopped in traffic on a very hot day, the temp will creep above 180. But it pulls down almost instantly once I’m moving.