I was thinking of upgrading my current water pump (non A/C) on my 1968 455 engine to a larger capacity A/C type and was wondering if it would help my cooling system as I just upgraded the radiator to a 4 core type. What would be the part number that I would be looking for?

 

I don't know if the water pump length changes the capacity. There were two different impellers and I believe the cast iron one may move more coolant. I've not hear of anyone changing the water pump to increase coolant flow, but we'll see what others think.


John

 

I'm a bit hazy on this but, it sounds to me like you want to upgrade from standard cooling to heavy duty cooling. If it's just that (without adding A/C), it appears to me that you will also have to change your water pump pulley, your crankshaft pulley, and your power steering pulley if you have power steering. The correct part number for a heavy duty water pump is 400269.


When you changed to a 4-core radiator, did you have to change the upper radiator support piece as well?


There are others on this site much smarter than me that can more readily provide the right answer than just my thoughts. I'm interested in seeing what it takes to convert from standard cooling to heavy duty cooling as well.


Randy C.

 

Hi Randy, yes I did change the radiator top plate to a 4 core type (one year only part) if I need to change all those other pulley I may not do it. I wonder if just changing the propeller of the water pump to a larger one would work and how do I find one is another story.

 

I'd want to see some data before assuming that the A/C water pump actually moves more coolant than the non-A/C pump. All cars which used the A/C pump also used a pulley set which drove the pump faster than the crankshaft. They did this not to move more coolant but to spin the fan faster. This was needed because along with this pump the thermal fan clutch was used which slipped the fan, spinning it slower than the water pump pulley. Without this pulley over-drive ratio, the fan spins too slow at idle when you need it most.


So .... if you're spinning the pump faster merely as a side effect of spinning the fan faster, you have to wonder if the A/C pump might actually be designed to move LESS coolant for a given RPM than the non-A/C pump. Remember, there's an upper limit to how fast you can spin the pump before it cavitates.


Does someone have one of each pump (with original impellers) and a barrel of water? Make some measurements for us!

 

398681 or 400269. Have found thru experience the 398681 water pump is easier to find.
If its non a/c you can use a KE water pump pulley and the KB crank pulley without changing anything. Plus more than likely those are the pulleys you have anyway. If you didn't change the lower radiator supports I am guessing four core was difficult to fit.

 

If it helps 400269 and 398681 propellers length is about 5.5 inches or so where as non heavy duty coolant are around 5 inches or so.

 

I remember a long time back someone posted pics of the regular WP and the HD cooling WP. I think there was a significant difference in the impeller size between the two.

 

I was really trying to see if I could buy a larger impeller and would it fit in my non A/C water pump? If I need to change a bunk of stuff to do it I will pass but I am still curious to know.

 

Pretty sure "you" do not change impellers.

I have done LOTS of mechanical work, and have never undone a water pump.

It requires speciall tooling, procedures, and equipment such as a press.

Not everyone can operate a press correctly. Witness the auto "experts" to which I took an alternator a while back to get the pulley pressed on. They heated the pulley on the coffee plate then put the alternator in the press and pressed it on.

I noticed they did not dismantle the alternator and mentioned it, and their reply was that they would be glad to not do the job. My friend says go ahead. W/o supporting the rotor, of course, they pressed the rotor on into the back frame and displaced the bearing and broke the brush holder which we found out weeks later when the engine fired up.

They should have just let me do it.