Water Pump Vanes (propellers)

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hcarr

hcarr

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I'm changing a leaking water pump on my 70 duster 340 and it is an 8 vane pump, The only ones around here are 6 vanes. Do I need the 8 vane one or will it be ok to buy the 6 vane one Thanks
Howard
 
i think you may be asking in vain


if i remember correctly one of them is for the ones equipped with A/C and one isnt
never been able to figure out which one is which though
 
According to 71 Manual the 340 had 8 vanes and the A/C 340 had 6 vanes. I also have a 75 Manual and doesn't have any specs on the pump. Also the vanes have a bigger Diameter on the non A/C, 4.38 for non A/C and 3.50 for the A/C. This goes back to recent post re; water circulating too fast.( do all A bodies overheat is the post).
 
A few years back I had to change water pumps. The 8 vane pump was replaced with a 6 vane one. Non a/c car.
I compared the two and the vanes on the 6 vane pump were larger. The 8 vanes were longer but not as thick. I never measured the vanes on both of them to compare the total vane surface area.
 
Someone mentioned in another post that cavitation (bubbles) would be the problem using the wrong impeller. The water pump pulley on A/C vehicles is smaller, meaning it spins faster, thus the smaller impeller is used so as not to make too many bubbles. The water pump pulley on non A/C vehicles is larger, meaning it spins slower and uses the larger impeller to make up for that slower rotational speed.
 
So why change the pulley and water pump for a/c, why not leave it the same for both?
 
brian6pac said:
So why change the pulley and water pump for a/c, why not leave it the same for both?
Click to expand...

Part of it is most A/C cars use two belts for the A/C compressor from 70 & later... Non A/C uses only one belt so gets a single groove water pump - alt - crank belt vs double pulley for A/C...


Not sure about the vanes..

Just don't cut a vein on the sharp edges...
 
The A/C vehicles have larger radiators and can flow/cool more water flow. That's why the A/C water pump needs different vanes/pulleys which mean increase coolant movement to take advantage of the larger volume/capacity of the A/C radiator.
 
The biggest rad in 70-71 was 22" in a Duster. In fact the 318 rad held 17 Qts. and the 340 held only 15 Qts. The stats on the pulley are .95:1on standard non A/C and on A/C is 1.31:1, which is telling me A/C pump turns slower. Who ever thought of all this confusing nonsense must be Einsteins brother.
 
Thanks guys for all the replies. I think I will go with another 8 vane.Thanks again
Howard
 
Thanks Mullinax95. I read the article and am going to check the prices out. Thanks!
 
I always heard the A/C pumps turned faster due to smaller pulleys. Faster rotation, less impeller area, about the same cooling...less drag?
 
the 6 vane was used on the a.c. cars and the hi perf cars. my experience tells us do not worry about it. you do want the stronger 1978+ pump with the 5/8" shaft, the earlier unit was 1/2" shaft with smaller bearings. aw7103 at rock auto. do not use a gigantic lower pulley
 
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