AC vs Non AC Water Pump comparison

[Isaiah Estrada]

Here’s a side by side of an AC vs Non AC water pump.

Left pump is a Non AC, right is w/ AC. Right pump is an ACDelco. I noticed that although it still has 6 blades, they’re a lot bigger than the ones on my OE pump!

Here’s my roached OE pump

The ACDelco’s blades extend farther than the OE unit, but it still fits perfect in the housing.

Now I had originally planned on running the 6 blade AC pump until I learned that removing the AC compressor involves swapping the pulleys entirely. What I also didn’t realize is that factory Non-AC cars used an 8 blade pump. I understand that this was to offset the larger pulley the Non AC setup requires as it spins slower than the smaller AC pulley.

Im not sure if it ever really made a difference? Now, im not smarter than the good folks who engineered these cars for Ma Mopar, so I played it safe and bought the 8 blade WP at a good price.

The difference between the two still seems pretty crazy! Looking at them both, I wonder if it even makes a difference? Especially in a street application.

I guess this post is both an informative one (for those making the swap to Non AC brackets) and also a question to see wether or not the 6 or 8 blade makes a difference!

I scored a nice used WP pulley from of our neighbors at FBBO. Cleaned it all up today, but still need to paint! Excited to be able to put everything together for reals this time. My previous photos were just mock-ups / test fits of my pieces on the motor (mainly cause I forgot how everything went on!)

 

[CBODY67]

As you discovered, both pumps probably move the same amount of water due to the differences in the pulley drive ratios. Yet everybody always believed that the 6-blade a/c pump was the best and consumed less horsepower to turn, as the old Direct Connection Race Manual said to use the a/c pump for drag racing applications. NOT knowing of the different pulley drive ratios back then!

Staying more toward the OEM design of the blades is probably better, too. Even with two more blades than the a/c pump.

It's all good!
CBODY67

 

[Big_John]

Some reading for you.... Start at post #191 (not quite 1/2 way down the page) and see how one guy tested a bunch of pumps.

Overheating issue resolved....interesting read !

 

[Loadrunner]

Easiest water pump - and oil pump - to change in the history of the world?

The big block Chrysler.

 

[67valiant 100]

Then theres the older 10 blade water pumps!

 

[1970FuryConv]

Some reading for you.... Start at post #191 (not quite 1/2 way down the page) and see how one guy tested a bunch of pumps.

Overheating issue resolved....interesting read !

I had always thought that 8 blade was for HP and HD applications regardless of air conditioning

Interesting that many of the pumps had flow decrease starting at 3000 rpm.

Also interesting that the old 8-blade marine pump, which is multi-directional, outperformed all others and had no high rpm flow decrease.
Pump #3 Thanks Big John!

 

[Ross Wooldridge]

Interesting - my understanding was that since there was more heat being dealt with on AC cars, the AC pump moved the coolant slightly more slowly to allow the coolant more time in the radiator to shed the extra heat, keeping temps at the same level as a non-AC pump would do in a non-AC equipped car.

 

[twostick]

Interesting - my understanding was that since there was more heat being dealt with on AC cars, the AC pump moved the coolant slightly more slowly to allow the coolant more time in the radiator to shed the extra heat, keeping temps at the same level as a non-AC pump would do in a non-AC equipped car.

The story I read years ago was the A/C pump moved less coolant because when the idle solenoid engaged to increase idle speed with the A/C on, engine temp actually dropped below spec at idle with a "standard" flow pump. I'm pretty sure this was an emissions thing from California.

That keep the coolant in the rad longer argument gets trotted out in thermostat no thermostat discussions too. I think there is a law of thermo dynamics that pretty much poo poos that notion tho I couldn't tell you what it is at the moment.

Kevin

 

[CBODY67]

Perhaps the issue of WHY the pulley drive ratios are different between a/c and non-a/c cars might be considered? Might this also be another instance of Chrysler's "over-engineering" ) (or "more precise engineering) things compared to other OEMs?

Obviously, there is an optimum flow rate through the engine and radiator for best results, which can also include radiator core sizing? Getting back to "the complete package" engineering orientation rather than just ONE item being changed when something else changes? Perhaps there might be some information hidden deep inside an aged SAE Transactions paper somewhere, like in the 1957 Transaction when the original B/RB engines? Or a MasterTech presentation on cooling systems?

Just some thoughts,
CBODY67

 

[saforwardlook]

After spending some time looking through this entire thread and the one from the B Body site, I am inclined to use the AC Delco water pump on my 440 applications where in California I want the best cooling at low engine speeds since the toughest area of engine cooling on my 440s is in low speed and idle conditions in moderate to heavy traffic in hot weather. It seems what matters for low speed maximum flow is having a vane that leaves minimum space between the vane and housing and the deepest vanes as well. Having straight or curved (inward) probably doesn't mean much as long as there is minimum chance for "leakage" between the vanes and housing and tall vanes.

Also, in the 1970's GM had the best engine cooling systems especially at low speeds with their cross flow radiators that had a lot more width than the Chrysler radiators that was most important under lower speed conditions and they also had the best a/c performance at low speed engine conditions in traffic as well with their rotary a/c pumps as well, and AC Delco is a Division of GM.

I also use high efficiency cores when rebuilding my original radiators to have greater than stock fin density and more rows of tubes that are slightly smaller than stock to achieve the highest fin density (I believe the best cores for high efficiency are the ones used by Glen Ray radiators, that do not have really small tubes for maximum fin density (that are more subject to clogging with an engine that isn't brand new and has some corrosion in the system despite the best flushing) so that they have a tube diameter that is in between the maximum efficiency cores and the standard larger tube cores). But they aren't cheap but worth it when everything is considered.

The thread also talks about Milodon and Mancini water pumps among others but I don't know what they look like so it is hard to tell from the information we have at present just what the best combination is yet. But looking at the AC Delco a/c water pump and its design that Isaiah Estrada posted, it seems about the best one can do.

The housing with the small hole vs. the open housing are also factors to consider for best low speed cooling as well as a high flow thermostat. For my considerations, I would likely choose the small hole housing and the high volume thermostat flow.

 

[Gerald Morris]

After spending some time looking through this entire thread and the one from the B Body site, I am inclined to use the AC Delco water pump on my 440 applications where in California I want the best cooling at low engine speeds since the toughest area of engine cooling on my 440s is in low speed and idle conditions in moderate to heavy traffic in hot weather. It seems what matters for low speed maximum flow is having a vane that leaves minimum space between the vane and housing and the deepest vanes as well. Having straight or curved (inward) probably doesn't mean much as long as there is minimum chance for "leakage" between the vanes and housing and tall vanes.

Also, in the 1970's GM had the best engine cooling systems especially at low speeds with their cross flow radiators that had a lot more width than the Chrysler radiators that was most important under lower speed conditions and they also had the best a/c performance at low speed engine conditions in traffic as well with their rotary a/c pumps as well, and AC Delco is a Division of GM.

I also use high efficiency cores when rebuilding my original radiators to have greater than stock fin density and more rows of tubes that are slightly smaller than stock to achieve the highest fin density (I believe the best cores for high efficiency are the ones used by Glen Ray radiators, that do not have really small tubes for maximum fin density (that are more subject to clogging with an engine that isn't brand new and has some corrosion in the system despite the best flushing) so that they have a tube diameter that is in between the maximum efficiency cores and the standard larger tube cores). But they aren't cheap but worth it when everything is considered.

The thread also talks about Milodon and Mancini water pumps among others but I don't know what they look like so it is hard to tell from the information we have at present just what the best combination is yet. But looking at the AC Delco a/c water pump and its design that Isaiah Estrada posted, it seems about the best one can do.

The housing with the small hole vs. the open housing are also factors to consider for best low speed cooling as well as a high flow thermostat. For my considerations, I would likely choose the small hole housing and the high volume thermostat flow.

Having a high flow thermostat helps a lot. I've been using the old RobertShaw design thermostats since Spring, 2021. I also concur that a well designed radiator core does wonders for cooling an engine prone to heat. Coolant fluids come in 2 basic states: liquid in the cooling jacket, then air cooling that through the radiator. Good fans w or w/o shrouding help a lot in this area. I'm using an old OEM pump with 8 blades and as big a radius as can be fit into the housing. I'm also considering a smaller pulley for the fan/pump. I have a non-AC pulley and pump for now, and things incontrovertibly cool best when its turning well.

Given how liquid coolant should maintain a fairly uniform temperature within the jacket so long as it FLOWS well enough, I don't buy the old saws about slowing the flow rate down to cool anything much better. Such certainly has never been the case with the 440 I had in 2004-05, or the 383 I have driven hard over 6 years now.

I DO very much subscribe to the notions of maximizing cooling surface! Both tube surface area and optimum fins radiating from those tubes make the best radiator. Since my venerable old copper radiator has sprung another small leak, I likely will shop for a good aluminum replacement short term, but have a good re-coring job, by USA or Glenn Ray if I can't find a local shop to do good work any longer. Like so many skilled mechanics, the old boy who used to do such great radiator work here has passed away. MOST lamentable! Whoever does it, I want that old 3 rows of copper expanded to 4 at optimum fin density.

 

[saforwardlook]

Having a high flow thermostat helps a lot. I've been using the old RobertShaw design thermostats since Spring, 2021. I also concur that a well designed radiator core does wonders for cooling an engine prone to heat. Coolant fluids come in 2 basic states: liquid in the cooling jacket, then air cooling that through the radiator. Good fans w or w/o shrouding help a lot in this area. I'm using an old OEM pump with 8 blades and as big a radius as can be fit into the housing. I'm also considering a smaller pulley for the fan/pump. I have a non-AC pulley and pump for now, and things incontrovertibly cool best when its turning well.

Given how liquid coolant should maintain a fairly uniform temperature within the jacket so long as it FLOWS well enough, I don't buy the old saws about slowing the flow rate down to cool anything much better. Such certainly has never been the case with the 440 I had in 2004-05, or the 383 I have driven hard over 6 years now.

I DO very much subscribe to the notions of maximizing cooling surface! Both tube surface area and optimum fins radiating from those tubes make the best radiator. Since my venerable old copper radiator has sprung another small leak, I likely will shop for a good aluminum replacement short term, but have a good re-coring job, by USA or Glenn Ray if I can't find a local shop to do good work any longer. Like so many skilled mechanics, the old boy who used to do such great radiator work here has passed away. MOST lamentable! Whoever does it, I want that old 3 rows of copper expanded to 4 at optimum fin density.

I agree pretty much with everything you say and are doing except that in my case I have never found a need for going more than 3 rows deep. I learned during my assignment at Chrysler's Chelsea Proving Grounds that for low speed cooling maximal radiator frontal surface area was of paramount importance and that if cooling at high speeds is an issue then the depth of the radiator and how many rows of tubes becomes the most important factor. Given that in the past California maximum temperatures rarely ever get above 112F, I have never had a higher speed cooling issue at all and my only cooling issue was low speed traffic so I focused on radiator frontal width and high fin density cores for maximum low speed cooling combined with a maximum of 3 rows of tubes ever. Since you live in Tucson, AZ though, your maximum temperatures exceed those of California routinely so maybe there could be a need for 4 rows of tubes, but so far I have never had a need for more than 3 rows of tubes.

Also, while at the proving grounds I learned that Imperials alone received the only 28" wide cores while the maximum of all other models including Chrysler was 26". This was done because Imperials in the late 60s and early 70s alone had temperature gauges and as such fussy owners of Imperials knew when their cars were running hot while other high end Chrysler models only had two warning ("idiot") lights that showed "cold" or "hot" and that was it. I believe that some Plymouth/Dodge owners also got gauges for some reason but that those owners wouldn't be as likely to complain as long as the cars didn't actually show overheating. Otherwise the other high end Chrysler model drivers would not know how hot their cars were operating since they only knew when it overheated. Chrysler didn't want a lot of complaints from fussy Imperial and Chrysler model owners since they all would have run hot with the 26" cores and those owners would know it and would have complained to their dealers about it. Bean counters again at work.

Thanks for your comments.

 

[1970FuryConv]

Having a high flow thermostat helps a lot. I've been using the old RobertShaw design thermostats since Spring, 2021. I also concur that a well designed radiator core does wonders for cooling an engine prone to heat. Coolant fluids come in 2 basic states: liquid in the cooling jacket, then air cooling that through the radiator. Good fans w or w/o shrouding help a lot in this area. I'm using an old OEM pump with 8 blades and as big a radius as can be fit into the housing. I'm also considering a smaller pulley for the fan/pump. I have a non-AC pulley and pump for now, and things incontrovertibly cool best when its turning well.

Given how liquid coolant should maintain a fairly uniform temperature within the jacket so long as it FLOWS well enough, I don't buy the old saws about slowing the flow rate down to cool anything much better. Such certainly has never been the case with the 440 I had in 2004-05, or the 383 I have driven hard over 6 years now.

I DO very much subscribe to the notions of maximizing cooling surface! Both tube surface area and optimum fins radiating from those tubes make the best radiator. Since my venerable old copper radiator has sprung another small leak, I likely will shop for a good aluminum replacement short term, but have a good re-coring job, by USA or Glenn Ray if I can't find a local shop to do good work any longer. Like so many skilled mechanics, the old boy who used to do such great radiator work here has passed away. MOST lamentable! Whoever does it, I want that old 3 rows of copper expanded to 4 at optimum fin density.

What is a Robert Shaw design thermostat? What makes it high flow? Thanks

 

[70bigblockdodge]

I always understood the A/C W.P. was to slow down the coolant with the large diameter crank pulley, and wide 26" radiator, to give it time to radiate more heat in radiator that is sitting behind a also heat producing condenser.
Referring to Steve's post. One thing I have never understood from Chrysler was the use of different radiator supports. Why not make them all large openings just put a smaller radiator in the opening like GM did. Now they have created a body build oops point, 22" rad opening with 26" radiator build sheet. One stamping for a car line since it is welded (not in C bodies) just seems like a more simplified way to do things.

 

[1970FuryConv]

I always understood the A/C W.P. was to slow down the coolant with the large diameter crank pulley, and wide 26" radiator, to give it time to radiate more heat in radiator that is sitting behind a also heat producing condenser.
Referring to Steve's post. One thing I have never understood from Chrysler was the use of different radiator supports. Why not make them all large openings just put a smaller radiator in the opening like GM did. Now they have created a body build oops point, 22" rad opening with 26" radiator build sheet. One stamping for a car line since it is welded (not in C bodies) just seems like a more simplified way to do things.

Plus it gives an option to go with a larger radiator if you got a 22 inch from the factory.

 

[70bigblockdodge]

Plus it gives an option to go with a larger radiator if you got a 22 inch from the factory.

For our benefit it would be great. On their side it would have simplified the QA and manufacturing. Seems like a very old school thinking left over from the body on frame days.

 

[Gerald Morris]

What is a Robert Shaw design thermostat? What makes it high flow? Thanks

THIS is a sketch of a RobertShaw type thermostat, from the 1968 Chrysler FSM:

Here is a link and pic to the Genuine Article, as it is sold today:

The original Robertshaw 330 series hi flow thermostats

You can see by the open style of the top, or engine side of the thermostat how readily coolant flows out, once the bottom opens. You can read the Flowkooler blurb to answer your questions.

In addition to Flowkooler/RobertShaw, several companies such as Holley (Mr. Gasket) and Milodon use this venerable design. Stant did, and Motorad, the Israeli company which gobbled them still has it on the shelf.

Milodon's stat.

The PLA of China has a number of cheap copy front companies making them too. These can be had for $9.99 on eBay, but I don't recommend them. Unfortunately, Holley's copy ALSO comes from the SAME plants now!

 

[saforwardlook]

One thing that shocked me as I was rotated throughout the company over a two year period is how different departments viewed their jobs. Some departments like cooling and a/c labs, body hardware, instrument panel lab and others really didn't seem to care much about how forward thinking, competitive and energetic there efforts were while other departments such as engine design, transmission design, suspension labs and body structure were very advanced and forward thinking with a competitive attitude. This lack of cohesiveness and one mind set hurt the company badly and eventually led to its bankruptcy circa 1990.

By comparison GM was far ahead of Chrysler in engine cooling and a/c performance/satisfaction and interior appearance and refinement and seemed to have a much more competitive spirit in delivering vehicles that excelled in satisfying customers where it was clearly felt. Their vehicles were generally more refined, smooth and quiet and the interior climate control systems delivered in spades and their engine cooling systems did not skimp. I saw all the competitive makes' data from proving ground tests of competitive vehicles.

 

[Gerald Morris]

One thing that shocked me as I was rotated throughout the company over a two year period is how different departments viewed their jobs. Some departments like cooling and a/c labs, body hardware, instrument panel lab and others really didn't seem to care much about how forward thinking, competitive and energetic there efforts were while other departments such as engine design, transmission design, suspension labs and body structure were very advanced and forward thinking with a competitive attitude. This lack of cohesiveness and one mind set hurt the company badly and eventually led to its bankruptcy circa 1990.

By comparison GM was far ahead of Chrysler in engine cooling and a/c performance/satisfaction and interior appearance and refinement and seemed to have a much more competitive spirit in delivering vehicles that excelled in satisfying customers where it was clearly felt. Their vehicles were generally more refined, smooth and quiet and the interior climate control systems delivered in spades and their engine cooling systems did not skimp. I saw all the competitive makes' data from proving ground tests of competitive vehicles.

No doubt of it, Chrysler committed suicide during the 1980s. The symptoms you describe point to failure in leadership. I fear Stellantis will wind up dismantling the entire Chrysler structure in this country, leaving nothing but web wikis....

 

[John Kirby]

I always understood the A/C W.P. was to slow down the coolant with the large diameter crank pulley, and wide 26" radiator, to give it time to radiate more heat in radiator that is sitting behind a also heat producing condenser.
Referring to Steve's post. One thing I have never understood from Chrysler was the use of different radiator supports. Why not make them all large openings just put a smaller radiator in the opening like GM did. Now they have created a body build oops point, 22" rad opening with 26" radiator build sheet. One stamping for a car line since it is welded (not in C bodies) just seems like a more simplified way to do things.

if you break down the build plate on the inner fender here is a code for the radiator support size. The 26" was for A/C equipped cars. I suspect the radiator was preattached to it. that would make it a lot easier to assemble the car on the assembly line. Unlikely there would be an assembly mistake in that case.