I need to replace the stock water pump on my Challenger 440BB (street driver). I am not overheating with my present pump and thermostat, but I am running close to the edge. I'd like to replace with a higher flow/volume pump and thermostat setup. I just want to replace the impeller and keep the cast iron housing. Any suggestions??

doesn't the pump for a/c big-blocks have more impeller vanes than the non-a/c version? Would be easier to get a parts-store pump than to change out the impeller

Not looking to change just the impeller. I want to replace the bolt on impeller assembly that bolts to the pump housing. Mine is a non-AC car.

What you are calling the bolt on impeller assembly is the water pump.

What you want to keep is the water pump housing.

That is the water pump. When you go to the parts store and say 440 water pump that's what they'll bring you.
The water pump housing is between the water pump and the block.

Edelbrock pumps are supposed to increase flow
FlowKooleer pumps likewise
Milodon sells some pretty good stuff and their water pump should be good

Don't try to install a cavitation plate on a pump. If you want this feature, buy the FlowKooler.

This subject is funny because back in the day a water pump was a water pump. Whatever Genuine Parts had on the shelf was IT. Or H. E. Everson.

R.

Milodon big block high flow water pumps already come with a cavitation plate already attached. Mine did anyway. The only thing I was disappointed in was it only had 6 vains. And if you don't already have a high flow thermostat, get one of those too.

How hot? is that a known accurate gauge? Is the issue stoplight to stoplight or on the highway or both? any recent part changes preceding a temp change? what setup do you have now (fan/schroud/radiator etc) timing/AF ratio in the ballpark? If the pump is needed a parts house 8 blader will suffice & you can cut a circular disc in half & tack weld the halves behind the vanes for an efficient anticav plate.

Less; A/C has 6 vanes, non-A/C has 8 vanes. A/C pump is overdriven 40%.

Many parts stores offer only the 6-vane pump for all applications. Can cause overheating.

If I were replacing a water pump and T stat today, I would pick the Mancini Racing high volume pump and Milodon stat.

That said, "close to overheating" is often/usually not a stat or pump issue. Usually the radiator is getting marginal, there is an issue with the fan & clutch or shroud is missing or damaged.

Hot rolling down the road usually means radiator is marginal. Hot at a standstill (only) usually means fan/clutch/shroud is hurting.

and aren't the ac pulleys smaller in diameter with the crank pulley at still 7 1/4" ? or do i have this backward ?

Yes overdriven 33%. With the AC, a condensor/larger (thicker) radiator used/needed, so with AC a faster fan speed was needed to move enough air at idle/lower speeds thru these obstructions but this faster pulley also cavitated the pump at higher RPM's so going to only 6 vanes took care of that at high RPM's & the faster pulley speed made the 6 vanes move enough coolant at idle/low RPM's. The axle ratio will affect this. My suggestion(s). 8 blade/adj vane clearances/cav plate/good high flow 180 or higher stat/MP clutch or rigid fan with the most blades/spaced properly into a schroud/air directed correctly thru rad/several drops of dawn dish soap/a 1/32 hole in the stat for fast fillup/elim air pockets on initial startup. A good setup will feel like a tornado in front of the radiator.

Not to high jack this thread, but I have a pulley question here. So if I'm running a 6 vane water pump which is supposably for an A.C. car, what size should the crank pulley be? (single groove crank pulley, 440 car). Thanks.

7 & 1/4"

I thought the crank pulley was suppose to be smaller in diameter for an A.C. car? I just measured mine and its 6 1/2 inchs across. (single groove pulley).

You may be right on that. I had just assumed that the pump one was reduced to overdrive it. Can you measure your pump pulley?

http://www.bouchillonperformance.com/products-pulleys

First off, single groove pulleys are for non AC setups, so you are already off in your combo.

The above link will have the diameters.

The water pump pulley is approximately 6 & 13/16. And as I said before the crank pulley is 6 & 1/2 inch.

This is a non AC car, but it has a 6 vane water pump on it, which if I understand it right is for a AC car. So if I'm running a 6 vane water pump what size should the crank pulley & water pump pulley be?

^^^ As you know you are underdriven (with deep(er) gears likely good as is above idle). A 8 blader (easier than a pulley swap)) would give more flow.

Just run the non AC pump, cheaper swap.

GATES 42032 $21.00 at Rock Auto

As to what pulleys to run, the Bouchillion site has that info.