The Stovebolt Site Forums The Shop Area Engine Shop 1946 Chevy truck/261 H2O pump help

I was wondering what water pump you've used with your 1961 261 motor? The radiator hits the fan right now, so I need a shorter/thinner pulley. Right now it's holding me up from finally being able to start it for the first time. (Motor runs fine, I've just never gotten a chance to drive my truck because of a frozen 216 Babbit upon purchase.) TIA!

It looks like you are using the stock water pump from the '61 engine? I believe you need to use the shorter water pump with the smaller pulley?

Thank you, UY! I found my original... Not sure it's up to snuff, but we're going to put it on to be sure all is OK before we order a new one.

Utah doesn't mean your original pump. He means a short shaft pump designed for this situation. The original won't work in the 261 block as the block requires a pump that is designed differently. In the 235 and 261 block the impeller of the pump protrudes into the block. In the 216 pump, the impeller is inside the pump body.

An alternative is to use your original 216 pump with an adaptor plate designed by one of the members of this forum. I have never done this myself but it has several advantages to the short shaft pump placement. Search this site and perhaps someone with details will chime in.

Also, note that the pulley on your 216 pump is for a 5/8" belt; the 261 and accessories use a 3/8" belt. You need to go one way or another in your build.

Kent

Thank you, Kent! Hubby ordered me a new water pump earlier today, and we already have a plate. Now if I can find some old clutch head screws for my interior I'll be well on my way. (I'm trying to avoid shiny new ones since it's an old farm truck, and I'm leaving the original patina.)

Just an FYI to readers since you've already ordered the parts: You can order a one or two shiv pully from Summit or others that fits a Chev V8. The short shaft pulley gives more than adequate space in my AD application. Once you have the pulley you need to press the mounting flange further onto the pump shaft by 1.1" IIRC, check this by measuring the difference between the six cylinder pulley and the V8 pulley. I have done this on a couple of pumps successfully. Do not press the flange too far because its difficult to press it back the other way and too much of an interference fit to use a gear puller.

When you're done relocating the flange, cut off the excess shaft it it seems necessary or desirable. Then, on AD trucks, You'll have to drill some extra holes in the radiator mounting frame to lower the radiator enough so the fan doesn't hit the radiator's water inlet at the bottom. I used a 6-blade, high-pitch 16" truck fan. Bigger fan will hit the lower hose. This setup has run for a couple decades with minimal overheating problems, certainly no worse than when it was stock with the high-mount fan and pulling a ton of hay up a steep grade on a hot day.

I just did this 261 update/conversion. I used my short shaft 216 water pump with a wide group pulley.

I used the relocator adapter plate for the pump. I already had the wide groove generator. Then I needed to come up with a wide groove harmonic balancer pulley. The fan has the proper clearance to the harmonic balancer and the proper spacing to the radiator. If changing harmonic balancer, If needed don’t forget to drill the appropriate holes in the gear cover for the front motor mount. I also drilled and tapped the crank.

Here are a few pictures that shows my set up.