The Stovebolt Site Forums The Shop Area Engine Shop Dual outlet water pump - Source?

Hello, I'm swapping a 216 for a 261 (Full pressure - 1962). I have an 848 head on the rebuilt motor properly drilled for steam holes. I was given (loaned) a water pump housing with a bypass around the thermostat. Would anyone have a NAPA number for the water pump I've seen with the dual outlet?

Thanks - Joe

Good luck, Joe. It will be nice if someone posts an available part number.

Do you need the dual outlets?

Joe, not a NAPA number, but here is the water pump you are looking for at RockAuto. I bought one recently...new, not rebuilt.

http://www.rockauto.com/en/catalog/chevrolet,1957,truck,3.8l+235cid+l6,1326091,cooling+system,water+pump,2208

The easy part is finding the water pump, the hard part is finding the thermostat for the bypass housing. If you do a search on this forum, you'll see threads about the thermostat issue.

Matt

Thanks Matt. I am lucky - I have the housing. I'll give it a try.

Tim - I was told if you could find the thermostat housing you should use it. I do know of guys running a regular housing on a 261 with no problems. Others claim you risk cracking the head. I believe the internet is a source of great information, even a better source of misinformation......Being an engineer I have faith in my predecessor engineers back in the 50's in designing these engines and cooling systems. I will try it.....

Now.......I need a belt pulley to fit on the water pump that Matt directed me to.

Joe, the problem you'll have is that the tstat is no longer made for the 261 bypass housing. If you search past posts on the subject, you will find lots of info. I beat this up about a year ago with lots of input from other members.

Yes, a non-bypass 235 housing can be substituted but without the bypass feature. Like you, I believe in how GM designed it, so here is a link with instructions of how to convert a 235 housing to one with a bypass. I run this design and it works great. Very easy, simple...and it works!

https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1163443/Re:_Converting_a_216/235_therm.html

The modified 235 housing will only work on a late model 235 or a 261 with a low water pump. It won't fit an early 235 or a 216 with a high water pump.

If you decide to use the modified housing, don't buy a dual outlet water pump like the one I sent you in the link. It won't fit because the upper casting hole is too close to the modified housing. (I know from experience because I bought one for the 261 under construction in my shop!) You'll want to use a single outlet water pump and tee into the heater return line as described in the instructions on the modification link.

If you have trouble finding the cone-shaped belt pulley that attaches to the water pump, send me a PM. I might have one laying around. Just an FYI...it is the exact same pulley on any late model 235 water pump.

Matt

I have used 235 thermostat housings and water pumps (1954) on two 261 engines - one for longer than 45 years.

What year truck will your engine be in?

If you put it in an Advance-Design or earlier truck, you should strongly consider using this water pump relocation adapter. With the adapter, you would use an older style water pump (later water pumps - any style- will not work). Use an older style water pump with a pulley diameter that matches your year, and a groove width that matches your year (generator groove and harmonic balancer groove widths).

You will not be risking cracking your 261's head, as long as the "848" head has been properly drilled for the extra coolant passages to match the 261 block.

Thanks Tim,
Thanks for the link Matt.

The 1962 - full pressure 261 will be installed in a 1947 1-ton AD dually. I'm not too concerned about fan clearance because I plan to mount an electric fan behind the grill. I know its not original but for now its the plan. I didn't know there is a tough time finding the t-stat Matt. The weighs into the equation. I may take you up on that pulley offer. A lot to think about. Good options. Is that tech tip on our site for a download or only available through the link above ?

Only on the link. It has been submitted for posting on the site.