Water pump pulley

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moparker

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What size pulley should a 71 Duster 340 non air car have? Also, would a larger or smaller make the water pump spin faster?
 
Thank you. Will measure mine tomorrow. Really trying to not leave any stone unturned. Gonna make sure this car runs cooler this year.
 
What size pulley should a 71 Duster 340 non air car have? Also, would a larger or smaller make the water pump spin faster?
A larger crank pulley will spin the wp and alt faster.

A smaller water pump pulley will spin the wp faster.
 
A larger crank pulley will spin the wp and alt faster.

A smaller water pump pulley will spin the wp faster.
Thanks for clarification into the theory of that. Yessir, a larger drive will move a belt faster. I'm in the Tampa area, and don't have overheating issues on my 340, w 4:10s. It was in a much heavier car ( 66 sat) in a Duster now. I could measure, if it will help anyone. All the pulleys are of the original 66 273 a/c mill that was in my old Satilite
 
My stock 67 dart 273 non ac has about
6 for the crank and 6.25 for the wp, slightly underdriven. No shroud, 7 blade fixed fan, cools fine .
 
My stock 67 dart 273 non ac has about
6 for the crank and 6.25 for the wp, slightly underdriven. No shroud, 7 blade fixed fan, cools fine .
No shroud! Wow Man! I drove mine daily in traffic for a few years, even in the Summer here. Always run a shroud here! Lol. That said, I'd Never daily drive my Duster now, unless it's 10 miles each way or less. SO MANY people have moved here in the last year or so, it's gotten crazy. And the majority cain't drive no how... I'll grab a tape and report back. Just so it's on file. I know that isn't the OP's need, but maybe it'll help someone else.... I have Learned So Much just "Thread Diggin"... lol
 
No shroud! Wow Man! I drove mine daily in traffic for a few years, even in the Summer here. Always run a shroud here
So Cal car
The dart was my dad's daily driver, he put 300,000 miles on it in 25 years
 
So Cal car
The dart was my dad's daily driver, he put 300,000 miles on it in 25 years
Man, That's cool as can be! Awesome! Ok, went out to the car. Hard to get an Exact # with everything in the way, and not using a square or 2 levels for reference, plus it's dark here. About 7. 125 or a .25@ crank and 6 to 6 and an 1/8 th or 1/4" for WP...was running a flex fan, switched to a clutch set up, supplied by some Good Mopar Brothers here. Haven't put the clutch set up in traffic in summer yet...
 
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Man, That's cool as can be! Awesome! Ok, went out to the car. Hard to get an Exact # with everything in the way, and not using a square or 2 levels for reference, plus it's dark here. About 7. 125 or a .25@ crank and 6 to 6 and an 1/8 th or 1/4"...was running a flex fan, switched to a clutch set up, supplied by some Good Mopar Brothers here. Haven't put the clutch set up in traffic in summer yet
Just FYI, I was born in ST. Petersburg in 1958. I was raised there until a nasty family thing, and moved to Seminole county in 1968. I left Florida when I joined the Marine Corps in 1977. After our marriage in 1987, we moved to Washington State. My wife and I just both retired in the past month. We're heading back to central Florida this summer or fall. Looking forward to taking my Swinger down the strip at Bithlo, now Speed World. We'll meet soon.
 
Just FYI, I was born in ST. Petersburg in 1958. I was raised there until a nasty family thing, and moved to Seminole county in 1968. I left Florida when I joined the Marine Corps in 1977. After our marriage in 1987, we moved to Washington State. My wife and I just both retired in the past month. We're heading back to central Florida this summer or fall. Looking forward to taking my Swinger down the strip at Bithlo, now Speed World. We'll meet soon.
Sounds Great! Looking forward to meeting Y'all as well, and Thank You for Your Service to this Great Country! I worked with quite a few Marines when i was doing Volunteer work. I was born at Ft Darnell Army Hospital, Texas, '71. Seminole County is Nice! There are still cool parts of Pinellas, but price and traffic is Insane! I'm actually kinda towards Plant City. Tampa has gotten silly. Speed World is about the only place around these parts anymore... Lakeland had test and tune, but been closed for many years..
 
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Moving the water faster sometimes makes it run hotter. The reason the max washer hole in the thermostat housing when the thermostat is eliminated should be 1 inch is to control the flow of the water. I ran 1 inch diameter hoses on my car with no thermostat. Slowing the water down made it run cooler.
 
Rat Bastid I see you disagree. There are plenty of articles that support what I said. Here is one from Hot Rod. There is also a section in mopar performance manual.


Marlan DavisWriter, Photographer
Jul 15, 2020
Engine Coolant Flow Rate In The Motor Should Have Enough Time To Fully Circulate And Absorb Heat, And In The Radiator For Efficient Heat Transfer Without Getting Into Laminar Flow
Faster is not better when it comes to engine coolant flow rate. The purpose of a radiator is to support heat transfer, which is a time-dependent process. As Flex-a-Lite explains, to move the heat from one medium to another (engine to coolant to radiator to atmosphere), the coolant has to remain in contact with a surface for heat transfer to take place. Moving fluid too quickly through an area can result in laminar flow, where the fluid forms layers. The layer closest to the surface moves slower than layers farther away from the surface. When this occurs, the layers act as insulators and the capacity to transfer heat is diminished.


A low RPM cruiser will benefit with a high flow rate pump. A high RPM performance car where the RPM's are consistently higher will not. Manufactures who sell overdrive pulleys and High flow rate pumps will never tell you that. It would diminish sales of their product.
Why do you think mopar had two different flow rate pumps in the 70's. A 340 took a different pump then a 318. Or a car with AC and without

Dig out your old Direct Connection manual and read. They also recommend a washer with a 1 inch hole . I ran 1 inch hoses on my car. The 1 inch NPT threads came right in the Moroso stat housing connector. Wonder Why????

Steve 102.JPG
 
Nascar at least at one time used restrictors in place of thermostats. But that would follow the continuous high speed engine part of the article.
 
Nascar at least at one time used restrictors in place of thermostats. But that would follow the continuous high speed engine part of the article.


They do that to set the MINIMUM OPERATING TEMPERATURE. That’s what it does. That article is wrong.

Others and I have all explained how backwards that thinking is and I’m not about to do it again. Speed the coolant up. As long as the belts stay on you will get better cooling.
 
[1] Yes, the article in post #15 is wrong. It ignores a fundamental point: if the coolant stays in the rad longer [ to supposedly get rid of the heat ], then the coolant in the engine will gets hotter because it is a closed circuit. Now, hotter coolant enters the rad for cooling than would otherwise be the case.
[2] Many people who hardblock their blocks report cooler running. Since most of the coolant volume is in the block, a large proportion of coolant [ for cooling ] has been removed from circulation [ pardon the pun ]. So how can that be, less coolant, runs cooler? The remaining coolant circulates more quickly because there is less of it & cooling is improved.
[3] Using a 1" spacer & it runs cooler. The 1" is about the open area of an open thermostat. If you add up the area of the coolant holes in the head gasket, that area is greater than the stat area. So the stat regulates flow, not the gasket holes, but more importantly the restriction of the hole/stat creates a pressure build up in the coolant. Hot spots can form in the heads, & cause localised boiling [ nucleate boiling ]. Boiling water contains air bubbles, a poor conductor of heat. By building pressure in the system, the bubbles are suppressed & cooling is improved. They were pretty smart those factory engineers!
[4] Go to tech tips on this website. Started by Howard Stewart, who made the Stewart racing water pumps & built his own WP dyno.
www.stewartcomponents.com
 
[1] Yes, the article in post #15 is wrong. It ignores a fundamental point: if the coolant stays in the rad longer [ to supposedly get rid of the heat ], then the coolant in the engine will gets hotter because it is a closed circuit. Now, hotter coolant enters the rad for cooling than would otherwise be the case.
[2] Many people who hardblock their blocks report cooler running. Since most of the coolant volume is in the block, a large proportion of coolant [ for cooling ] has been removed from circulation [ pardon the pun ]. So how can that be, less coolant, runs cooler? The remaining coolant circulates more quickly because there is less of it & cooling is improved.
[3] Using a 1" spacer & it runs cooler. The 1" is about the open area of an open thermostat. If you add up the area of the coolant holes in the head gasket, that area is greater than the stat area. So the stat regulates flow, not the gasket holes, but more importantly the restriction of the hole/stat creates a pressure build up in the coolant. Hot spots can form in the heads, & cause localised boiling [ nucleate boiling ]. Boiling water contains air bubbles, a poor conductor of heat. By building pressure in the system, the bubbles are suppressed & cooling is improved. They were pretty smart those factory engineers!
[4] Go to tech tips on this website. Started by Howard Stewart, who made the Stewart racing water pumps & built his own WP dyno.
www.stewartcomponents.com
You nailed this.
 
[1] Yes, the article in post #15 is wrong. It ignores a fundamental point: if the coolant stays in the rad longer [ to supposedly get rid of the heat ], then the coolant in the engine will gets hotter because it is a closed circuit. Now, hotter coolant enters the rad for cooling than would otherwise be the case.
[2] Many people who hardblock their blocks report cooler running. Since most of the coolant volume is in the block, a large proportion of coolant [ for cooling ] has been removed from circulation [ pardon the pun ]. So how can that be, less coolant, runs cooler? The remaining coolant circulates more quickly because there is less of it & cooling is improved.
[3] Using a 1" spacer & it runs cooler. The 1" is about the open area of an open thermostat. If you add up the area of the coolant holes in the head gasket, that area is greater than the stat area. So the stat regulates flow, not the gasket holes, but more importantly the restriction of the hole/stat creates a pressure build up in the coolant. Hot spots can form in the heads, & cause localised boiling [ nucleate boiling ]. Boiling water contains air bubbles, a poor conductor of heat. By building pressure in the system, the bubbles are suppressed & cooling is improved. They were pretty smart those factory engineers!
[4] Go to tech tips on this website. Started by Howard Stewart, who made the Stewart racing water pumps & built his own WP dyno.
www.stewartcomponents.com
Wonder why the outlets on the electric pumps are 1"? and also all the newer cars went to a smaller upper thermostat outlet.

When checking the cooling of the engine you are all thinking of the water temp . Did you ever think of comparing it to oil temp. I had a mechanical water temp, Oil Temp. and Trans temp side by side. I did compare them and slowing the water up lowered the engine temp. I also had engine oil temp with engine oil cooler temp.

We were trying this at a Nascar race shop to see what the temps were comparing them for street driving. Decreasing the hole in the stat improved cooling. I already had 1" hoses so I went as small as a 5/8 hole doing tests in 1/8 increments. watching oil water, and block temps with gauges and a laser thermometer . Cruising at 75 -80 MPH with a 5500 converter and 456 gears 28 inch tires

You all can tell me your engineering calculations and test on dyno's . We did this on the street recording all the data using equipment we know worked. I would trust these Nascar guys 100%. Tony Hirschman and Matt Hirschman. Super modified Troyer nascar shop. Tony Jr. works for Kyle Bush.

I could hammer on my car round after round shifting a 8500 and the temp never came off 190. Trans temp would always climb first.

I am not saying in certain combinations just scrambled together wouldn't benefit from slowing the water down. But it definitely worked for me. Believe me the cost for the work was not cheap due to the parts we were using at that shop. But the benefits paid off. Running Hot, boiling fuel, flare on the shift when hot. Now that we have it figured out the new motor will be bigger and more consistent in the new car.

.
 
. Cruising at 75 -80 MPH with a 5500 converter and 456 gears 28 inch tires
WOW! What rpm were you turning while cruising 75 mph with 4.56 gears and a 28” tire? 5000? I have 3.91 with 28” tires and turn 3000 at 60mph. That thing must have been singing!
 
WOW! What rpm were you turning while cruising 75 mph with 4.56 gears and a 28” tire? 5000? I have 3.91 with 28” tires and turn 3000 at 60mph. That thing must have been singing!
I put 4:56s in my 68 Coronet 383 4 spd car., back in the early 90s. Put it on 275 ONCE.. open headers, lasted about a week..... car Was sick w/ them! But She Ran like a Scalded dog, w/ 3:55. Miss my Baby Still!
 
WOW! What rpm were you turning while cruising 75 mph with 4.56 gears and a 28” tire? 5000? I have 3.91 with 28” tires and turn 3000 at 60mph. That thing must have been singing!
it was around 4000 rpm @ 75 . What I can tell you at 8500 in drive The speedo was well over 150

Time slips in the quarter were 10.50's at 130 mph. RPM's were just a little over 7000 maybe around 7200 through the lights The car was to heavy to achieve better. It weighed 3850 without a driver. compression was low the top rings were shot for these times. shift light set at 8000 for this pass
 
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