The Stovebolt Site Forums The Shop Area Engine Shop 1946 Chevy 5.7 L Engine swap with short water pump

Hello Bolters,

I have just put in a mid-dressed 350 Vortec (1996-2000) crate engine (no pulleys) in my 1946 Chevy 1/2 ton. I want to put a short water pump in so I can run a mechanical fan vs an electric for better air flow. The engine came with the long style water pump. I plan to run AC but no power steering. I was looking at using a serpentine belt vs. v-belt. I know there are kits from different vendors but don't need anything that flashy and would be happy to pull parts. Just want my belts to line up close and use shims for the final alignment.

Thank you,
Bill

The serpentine belt and pulley system on a 4.6 L V6 is almost identical to the V8, and there are dozens of them in most "you pull it" parts places. That should be a good beginning point.
Jerry

Thanks Jerry.

Does the 4.6 use a shorter water pump? I'm not experience with the 4.6 or any LS set-ups but I thought the short water pump was old school and V-belt era. My 1957 283 has the short pump as does my '78 Vette with stock 350, all with V-belts. The 4.3 V6 has the same front accessories as the 350 but I don't know the alignment layout between the V-belt and serpentine.

All the pulleys, tensioner, and idlers are in the same plane on a serpentine system, so the water pump shaft will be in line with the crankshaft pulley. That's about as "short" as it can get. The only reason for a longer shaft on the water pump would be to align the pulley with an extended sheave on the crankshaft. Some V belt systems have two or even three layers of belts.

Another option may be to use 4-groove pulleys instead of 6-groove. I don't know if they are available for that year. I have 4-groove pulleys on my '88. Seemed to be an option for the non-air versions, also don't know if a compressor will play nice with the 4-groove serpentine belt. I have also heard about ditching the fan clutch for tight setups, but that comes with more noise. I admit I didn't know about the short water pumps for LS until I went down that rabbit hole. A search on-line revealed to me they are a thing. The Stovebolt short pumps were simply the regular pump with the flange pressed down and the shaft cut off. A custom pully was made. There was the concern that the flange could slip during operation and cause heat issues. I never had a problem with mine. The later short pumps had shorter legs, taller pumps had a gap between pump and block. I had noticed the gap on one of my v8 engines, now I know a little more about it. I put the '88 v8 in my '47 and moved the radiator forward.

I have been looking at my '57 trying to figure out how to quiet down the cooling fan. My original 283 V8 has the short pump and a twin groove pulley system, the fan blade is 5 blades and the flange of the pump is 2 inches from the radiator. I could move the radiator forward about 1/2 inch but it won't give enough room for a clutch. I don't think a pusher electric fan would do enough and there isn't space out front. I will probably have to live with the original design.

My original thought was to go with the mechanical fan. I recently put in my radiator and have 3 1/8 inch between the flange and the back face of the radiator. If I switch to a short water pump, I should have about 4 3/4 inches possibly. However, my SBC sits low in the engine compartment and the fan would only be centered on the lower 1/2 of the radiator.

A mechanical fan will give the best CFM, if you can fabricate a shroud for it and keep the leakage to a minimum, it won't matter if the fan is off-center.