I have a 235 from a '57 car which has a water pump with a "B" sized v-belt pulley. I thought I would just swap it for an "A" belt pulley, but it appears that the pulley is pressed onto the shaft, not just sitting over the pump flange . The holes for the fan bolts are tapped into the pulley. It seems I can't do much with this pump/pulley. Looks like maybe the water pump is from an earlier 216 Stovebolt (which ran a "B" belt). I may just leave it with the B pulley (water pump operates fine), but what would happen if I ran the smaller A belt in this pump? It previously ran an "A" belt, and the base of the "B" pulley is all shiny from where the belt was running. The crank and generator are "A" size pulleys.
It doesn't sound like your engine is from a '57. From 1955-62, 235s used a water pump with a removable pulley. Adapter plates are out there that allow the use of an earlier 216/235 pump with a pressed on pulley on the later blocks. Is this what you have?
The 'A' belt will bottom out in the pully and not 'drive' the water pump as it should The sides of the belt are actually the point of contact that should drive the accessory....and a water pump not turning as it should is a recipe for disaster... If you are sure that you have the proper pully to place on the shaft, once you get the existing pully off, you could just cut it off.....score or almost cut it to the shaft... with a cutoff wheel on both sides of the pully...then drive a wedge (cold chisel) and split it in two...but don't listen to me necessarily...I have been known to be a 'hack' taking things apart.... If you heat the pully you want to place on the shaft....and chill the shaft, I bet it will slide on, you just ahve a very ssmall window to make it happen that said, there must be a way to press the old one off.....I've always wondered maybe someone will chime in and straighten us out... good luck
It is pretty common to put the 54 pump or earlier 216 pumps on 55 and later 235/261 engines to get fan to radiator clearance in earlier =48 Chevy pickup/car. It looks like Davis speed is currently out of his adapter plate to put a 216 water pump on a later 235 that raises the water pump up a bit higher than the 235 pump sits at. No show and tell there to see if your engine has one of those plates on it. Rock Auto shows pumps for 53/55 with either pulley. You have to sort though the offerings but the numbers should be good locally if local doesn't hit you with rare parts prices. That should let you have a pulley that matches the others you want to run. An easier to sort though list is 54 truck 1954 CHEVROLET TRUCK 3.8L 235cid L6 Water Pump | RockAuto As I had shortened a 56 235 water pump and used a shorter V8 pulley when I swapped a 56 235 into my friend's 53 Chev 3100 40 something years ago I brought out the 56 pump for show and tell. This is my education for the day in 51/55 216/235 water pumps as the two belt size thing hadn't come up that I can remember. Davis speed Home - Davis Speed Equipment has info if you click on find your engine and then open the 216/235/261 guide.
I have checked the casting number on the engine, and it is correct for a '57 car. Mr.48Chev gave a clue, it is in a '53 3100, so the 216 pump was installed for radiator clearance. The pictures are a big help, I can see that I have a 56-on pump with a pressed-on B pulley, but my pulley is not cast. I can get my hands on a pump with the mounting plate (top picture) although it has a removable A pulley, I should be able to shorten this.
This was the one we did probably 35 years after we built it in the high school autoshop. It had the narrow 56 belt though. The pulley, we dug around in the box of old pulleys that was in the shop until we found one that was somewhat shorter than the stock truck pulley. I think it was V8 Chevy. We laid a straight edge across the 235 pulley and measured the difference on the pulleys and then pressed the hub down exactly that amount and cut the end of the shaft off.
I have taken a pump off my spare engine , and now I can see why they are different- my original pump's impeller sits in a big hole in the front of the block, and the other has 2 smaller holes at the top of the block. I should be able to just swap pulleys (they are both pressed onto the shafts, which look to be the same size), I am going to modify a steering wheel puller to suit. I am concerned with heating up the pulley too much and cooking the seal, so I will leave the pump out in the sun (should be around 85F today) and give it a go.
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