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Water Pump Info circa 2019

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Repsolroger View Drop Down
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    Posted: Jan/01/2022 at 6:43pm

Edelbrock - Water Pump AMC Short Style 1968-72 (Part No. 8831) will this fit a 1969 390 .. some sites say yes...then others dont...and some ask if my engine is a W or X ... that stuff is expensive expensive ...so want to make sure before i add to cart and send it to someone 


1969 sst javelin restomod
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: May/26/2019 at 1:05pm
To add to your great thread...

I purchased a standard GMB pump for mockup for working on my mixed year parts engine setup.

GMB 110-1040A

It seems that it shares the same shaft specs as the performance GMB pump.

QUESTION:

IF the diameter is the same from flange to bearing for the oem late pump version... Other than the impeller difference, I assume the GMB shaft design with its corresponding bearing, will be a better option than the factory with smaller diameter shaft at the bearing?

Only if we had a bearing OD to compare with between the GMB pump and late model oem pump, to see if there is a slightly larger bearing bore OD at the GMB snout, for the larger GMB bearing ID... "If" the above question is validated by a confirmation on bearing ID size differneces between OEM and GMB.

71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ChillyB Quote  Post ReplyReply Direct Link To This Post Posted: May/26/2019 at 6:06am
You're right.  Mine is for a 73.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Greyhounds_AMX Quote  Post ReplyReply Direct Link To This Post Posted: May/25/2019 at 7:36pm
Yours is a later model long pump, and my Napa pump was an early model short pump for 68-72. It had an AMC part number on it so had to be a reman, I bought it around 2001 or so.

We can't see the top of yours from the pic but the later model pump will have the bypass clocked at the 12:00 position as well as the 4-3/4" or so length. 
1968 AMX 390 w/T5
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ChillyB Quote  Post ReplyReply Direct Link To This Post Posted: May/25/2019 at 6:22pm
How old is the photo of that NAPA water pump?  Here's the one I just got a month ago.  Looks very different drom that photo. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Greyhounds_AMX Quote  Post ReplyReply Direct Link To This Post Posted: May/24/2019 at 12:48pm
I measured and found that the GMB aluminum pump only has 3/16" of clearance between the back of the fan mounting flange and the shaft seal face. 

So even if the lower tier 110-1040AL version has a 0.625" shaft all the way, there's not enough room to push the flange on further and make it line up with an early crank pulley. It would need to be pressed on 5/16" further, and there's only 3/16" available.
1968 AMX 390 w/T5
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Greyhounds_AMX Quote  Post ReplyReply Direct Link To This Post Posted: May/21/2019 at 12:32pm



So I ordered the GMB-1040P, which is their aluminum high-performance pump version. Again, here's their lineup: 

1) 110-2908: Cast iron stock replacement pump, long housing, late model design.

2) 110-1040AL: Aluminum housing long late model pump.

3) 110-1040P: High-performance version of 1040AL. 

They tout the 1040P high-performance version as having a better impeller and better bearings, and compared to the stock replacement version that appears to be true. The shaft on the 1040P is larger than stock at 0.750" diameter, and is turned down to 0.625" for the pump mounting flange, which is really nice as then the bearings are larger. Unfortunately it does prevent us from pressing the flange on further to make a long pump into a short pump. The impeller on the 1040P is a different shape than the stock replacement version, having the same number of vanes, but they are longer. The lower cost 1040AL appears to use the same impeller design, so I expect that the difference between the 1040AL and the high-performance 1040P is the larger shaft/bearings used in the 1040P. 

Here you can see the larger shaft diameter as it comes out of the pump housing, then back down to 0.625" for the mounting flange. 

For comparison, here's a NAPA pump, the shaft is 0.625" diameter all the way through.



If you consider that the GMB pump flange location is actually 3/8" further out than the stock pump shown (late model vs early pump), you realize that the GMB housing extends out further than the stock unit did, placing the bearing closer to the load. And if you compare the relative diameters of the bearing housing area to the diameter of the fan/pulley flange, it's looks like the GMB casting is a bit larger OD in the bearing area. And it has a bunch of reinforcing ribs as well.


Edited by Greyhounds_AMX - May/21/2019 at 12:44pm
1968 AMX 390 w/T5
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red Devil Quote  Post ReplyReply Direct Link To This Post Posted: May/16/2019 at 12:09pm
I have a Flowkooler aluminum pump (GMB with Flowkooler impeller) with a thermostatic clutch 18" fixed fan (heavy compared to a stock flex fan), PS with AGR pump, Delco alternator on my '74 Javelin 401.  Sees 6500 rpm on occasion (rev limiter).   Been fine for 10 years, but just a summer cruiser so not lots of miles. 
Different combinations will have different harmonics and different loading.  If you're concerned, save up and buy an Edelbrock pump.
 
Hope this helps, RD.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bigbad69 Quote  Post ReplyReply Direct Link To This Post Posted: May/16/2019 at 8:24am
Originally posted by ChillyB ChillyB wrote:

Holding a spinning bearing isnt a tough job and the side load on the bearing due to belts and weight of fan seems insufficient to break anything.
If the rotating assembly is even slightly out of balance, it will vibrate. Those vibrations will be transmitted directly to the bearing. The amount of vibration will be determined by the amount of imbalance, the mass of the rotating assembly, and the RPM. Vibrations will also grow exponentially if the system encounters a resonance.

There are lots of variables. If the bearing and bearing retainer (in this case the pump casting) design is marginal, some will fail, and some won't.
69 Javelin SST BBO 390 T10
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Post Options Post Options   Thanks (1) Thanks(1)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: May/16/2019 at 7:16am
There are at least 2 guys in the Detroit area that rebuilds original water pumps if anyone is interested.  I have been taking a few of my cores with the part numbers in to this fellow.  He is very reasonable, ships, and has a one year warranty.  I will post up pictures etc. when I get a chance. 
Dan Bailey
4706 Detroit St
Dearborn Hts, MI 48125
313-530-2893



Edited by SC397 - May/16/2019 at 7:31am
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