The Stovebolt Site Forums The Shop Area The HiPo Shop SBC Water pump pulley and fan

I am building my 1950 3600 wth a 383 SBC that was originally a 1991 CK2500 350 engine. I obtained a new short water pump from Summit as part of the build.

I received a water pump pulley yesterday and found that it uses the smaller bolt circle mouting holes in the water pump (the pump has two sets of pulley mounting holes, one smaller than the other). The pulley also appears to sit at least an eighth of an inch further from the engine than the crankshaft pulley and has that much clearance to the water pump. I have contacted the supplier to determine their return policy.

The fan/clutch from the original 1991 (long water pump I believe) uses the larger water pump bolt circle so the pulley and clutch/fan can not be bolted in place as is.

I am wondering if anyone running a SBC is using the clutch/fan arrangement or if it will be too long to fit a radiator (not sourced yet). If so how did you resolve the clutch/fan fit with the short water pump pullley (different bolt circles). I anticipate that an electric fan and shroud arrangement would be shorter and avoid the bolt circle problem if I need to go that direction.

I am also wondering if there is a preferred source for the short water pump pulley. Alan Grove (where I obtained the crank pulley and alterntor mounting bracket) is out of stock and buying from E-Bay sellers appears to be a gamble.

My thought is that the short pump is where you are having issues. The short pump was used in early applications (1960's) and in the Corvette up to maybe 1980. The long pump is by far the most common on all the small blocks with brackets and pulleys being designed for mostly the long pump. I would stay with all long pump equipment, the difference between them is only roughly 3/8" in depth.

Isn't there enough material on either the pump flange or the pulley to turn it 45 degrees and drill some properly-spaced holes? Why depend on somebody else to make something fit when any properly equipped shop should have a drill press?

I've always used shims to correct minor errors in belt alignment- - - -either on the crankshaft pulley or the water pump.
Jerry

78buckshot, thanks I suspect that you are correct about the problems being related at least in part to the short vs. long water pump but I beleive the short pump provides 1 3/8" more clearance at the front of the engine for fans/radiator.

Jerry, thanks for the input, there is material to drill holes for the alternative bolt pattern in the pulley if I keep the pulley and if the clutch/fan is going to be used. I don't need to drill the alternative bolt holes if the clutch/fan will not be used. I had not thought about shimming out the crankshaft pulley to align with the water pump pulley so thanks for that suggestion.

Use a full circle disc of soft aluminum as a shim, not washers. I rough out the center hole with a big hole saw in a drill press when making a spacer, then finish off with a half-round file in a vise, or just spin the disc up on the lathe and machine the final diameter. I'd be a lost ball in high weeds without a machine shop a few steps out the back door, for both gunsmithing and hotrodding!
Jerry

look to see if the fan mount flange has an 1/8 " space between it and the pump housing. If so you can remove the rear plate, support the shaft, and press the flange back the amount needed for alignment. Follow Jerry's advice for hole relocation or just pull flange off and press a big pattern one on.

First round on my blower motor, I got the short pump but it seemed to have a metric bolt pattern or something weird. Did more research, found an earlier version pump, and a pulley that matched. And it lined up with the crank pulley. Maybe I lucked out. All Summit stuff.

I have a 46 and things got too tight so I went to a short water pump and electric fan. I would not drill any new stuff. I would talk to Summit and get the right stuff. We had to use a spacer. They come in a kit you can buy them on line.

Coilover, unfortunately the pump pulley flange appears to have an integrated spacer so nothing to remove to relocate the mounting surface.

Jerry, I made an aluminum disc spacer that was 0.125 thick and that seems to provide reasonably good alignment between the crank and water pump pulleys. I needed to use a mix of parts to get the alternator pulley far enough out to get it close to alignment.

Looking at the radiator support mounting surface for the radiator and the clutch/fan arangement it appears I would have clearance for the fan so I am planning to drill the alternate mounting bolt pattern in the water pump pulley to allow everything to mount for now. I can always remove the clutch/fan and go to electric later if I determine more clearance is required.

I did some additional checking and the alternate bolt pattern on the water pump flange is not the same as the clutch/fan bolt pattern. While I could probably modify the clutch fan to the pulley bolt pattern I thinkI am just going to mount the pulley and go the electric fan route.

using the original 91 fan and clutch assembly poses another problem. the 91 would have had serpentine belt setup with the a reverse rotation water pump. the fan would be turning the wrong way on a v belt setup

Thanks, I had not thought about the rotation problem!

WICruiser I suppose you know you can take the back off of your pump and press that hub anywhere you want it ?? Could also shim your harmonic balancer out too. Same with the 235 stuff.

I shimmed the crank pulley out with an aluminum spacer. I really did not want to take the new water pump apart and try to press the flange on further, the back sie of the flange has an integrated shoulder that gets very close to the pump housing so I could not determine (without disassembly) if I could move the flange without casuing seal problems.

I went the electric route with my truck - ‘54 3100 , ‘67 Camaro stub. My reason was lack of space for a conventionally mounted fan. No regrets here.