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Water Pump Info circa 2019

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Greyhounds_AMX View Drop Down
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    Posted: May/13/2019 at 12:31pm
The situation changes with time, but here's the current state of affairs as I am seeing it.

Excluding the early V8 variants, there are two basic water pumps that folks need the most:
1) 68-72 version: 4-1/2" hub height, bypass connection at 11:00 position
2) 73-up version: 4-7/8" hub height, bypass connection at 12:00 position

At this point in time it's become very hard to find an off the shelf 68-72 water pump. The only one listed at RockAuto for example is the GMB 110-2908 (cast iron), which has the wrong shaft length, the bypass connection is in the late model location, and it appears to hit the harmonic balancer as well. If you want a correct 68-72 water pump you'll probably need to send one out to have it rebuilt, or buy a rebuilt unit from one of the AMC vendors who usually keep them on hand. They do have a core charge however.

Aluminum 73-up pumps are available from multiple supplies, and all appear to use the same basic GMB casting, except the Edelbrock pumps. The casting quality is a huge step up from the cast iron pump bodies, with larger passages and more concentric connections. Here's a rundown of those aluminum pumps:

GMB 110-1040AL ($28) - Standard replacement. 12 month / 12,000 mile warranty.

GMB 110-1040P ($45) - High performance, better bearings, better seal, better impeller. 12 month / 12,000 mile warranty.

Airtex AW3401H ($52) - High performance, better bearings, better seal, better impeller. Lifetime warranty.

Flowkooler 1781 ($93) - CNC billet 16 vane impeller with anodized coating, reduced impeller clearances. 4-13/16" hub height. 2 year warranty.

Milodon 16271 ($104) - High volume. 4-13/16" hub height. 180 day warranty.

Here's some comparison pics of a typical cast iron pump casting with the GMB aluminum casting, courtesy of one of the fsj sites. Based on this and the variety of available offerings I can't see any reason to use a cast iron water pump.




Edelbrock offers water pumps in both common hub heights, and therefore has the only 68-72 aluminum pump available. The same casting is used for both, so the only difference is in the hub height.

Edelbrock 8831 ($273) - 68-72 short pump

Edelbrock 8832 ($281) - 73-up long pump

1968 AMX 390 / T5
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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/13/2019 at 12:35pm
There is a new update on water pumps... Galvins and others now carry proper pre 73 pumps. I will look up the link and add it... this is from Galvins site.

http://www.ramblerparts.com/product_info.php?products_id=665

Edited by 304-dude - May/13/2019 at 12:40pm
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 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: May/13/2019 at 12:53pm
Here is Galvin's new water pump

http://theamcforum.com/forum/6872-v8-correct-new-water-pump-photo_topic98457.html

As a side note... through the years now, a few have updated their water pump and pump pulley to retro fit newer pumps on late 68 to 72 cars. Also the two styles have different diameter bypass nipples, outside of the clocking.

A second note is some of the performance brand named pumps are relabeled GMB pumps.

I noticed with GMB pumps, they give two different height spacers for proper fitment with accessories.

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/13/2019 at 12:55pm
I have two engines: a 77 and a 73.  I noticed one of the bokt boss heights were different so I had to move over a water pump when I swapped engines (dropping in a running engine to get by for a while).

Just got a new one from NAPA.  They no longer discriminate, cutting the bolt boss low then including spacers to raise it back up if thats the accessory bracket type you need.  They also dont take a core return.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sonic Silver Quote  Post ReplyReply Direct Link To This Post Posted: May/13/2019 at 5:41pm
Originally posted by Greyhounds_AMX Greyhounds_AMX wrote:

The situation changes with time, but here's the current state of affairs as I am seeing it.

Excluding the early V8 variants, there are two basic water pumps that folks need the most:
1) <span style="font-family: Calibri, sans-serif; font-size: 11pt;">68-72 version: 4-1/2" hub height, bypass
connection at 11:00 position</span>
2) <span style="font-family: Calibri, sans-serif; font-size: 11pt;">73-up version: 4-7/8" hub height, bypass
connection at 12:00 position</span>
<span style="font-family: Calibri, sans-serif; font-size: 11pt;">
</span>
<p ="Msonormal">At this point in time it's become very hard to find an off
the shelf 68-72 water pump. The only one listed at RockAuto for example is the
GMB 110-2908 (cast iron), which has the wrong shaft length, the bypass
connection is in the late model location, and it appears to hit the harmonic
balancer as well. If you want a correct 68-72 water pump you'll probably need
to send one out to have it rebuilt, or buy a rebuilt unit from one of the AMC
vendors who usually keep them on hand. They do have a core charge however.<o:p></o:p>

<p ="Msonormal">Aluminum 73-up pumps are available from multiple supplies,
and all appear to use the same basic GMB casting, except the Edelbrock pumps.
The casting quality is a huge step up from the cast iron pump bodies, with
larger passages and more concentric connections. Here's a rundown of those
aluminum pumps:<o:p></o:p>

<p ="Msonormal">GMB 110-1040AL ($28) - Standard replacement. 12 month /
12,000 mile warranty.<o:p></o:p>

<p ="Msonormal">GMB 110-1040P ($45) - High performance, better bearings,
better seal, better impeller. 12 month / 12,000 mile warranty.<o:p></o:p>

<p ="Msonormal">Airtex AW3401H ($52) - High performance, better bearings,
better seal, better impeller. Lifetime warranty.<o:p></o:p>

<p ="Msonormal">Flowkooler 1781 ($93) - CNC billet 16 vane impeller with
anodized coating, reduced impeller clearances. 4-13/16" hub height. 2 year
warranty.<o:p></o:p>

<p ="Msonormal">







<p ="Msonormal">Milodon 16271 ($104) - High volume. 4-13/16" hub
height. 180 day warranty.<o:p></o:p>

<p ="Msonormal">Here's some comparison pics of a typical cast iron pump
casting with the GMB aluminum casting, courtesy of one of the fsj sites. Based on this and the variety of
available offerings I can't see any reason to use a cast iron water pump.<o:p></o:p>

<p ="Msonormal">

<p ="Msonormal">

<p ="Msonormal">

<p ="Msonormal">

<p ="Msonormal"><p ="Msonormal">Edelbrock offers water pumps in both common hub heights, and
therefore has the only 68-72 aluminum pump available. The same casting is used
for both, so the only difference is in the hub height.<o:p></o:p>

Edelbrock 8831 ($273) - 68-72 short pump

<p ="Msonormal">Edelbrock 8832 ($281) - 73-up long pump

My Edelbrock short pump has the bypass at 12 o'clock.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 69 ambassador 390 Quote  Post ReplyReply Direct Link To This Post Posted: May/13/2019 at 10:18pm
Originally posted by Greyhounds_AMX Greyhounds_AMX wrote:

The situation changes with time, but here's the current state of affairs as I am seeing it.

Excluding the early V8 variants, there are two basic water pumps that folks need the most:
1) 68-72 version: 4-1/2" hub height, bypass connection at 11:00 position
2) 73-up version: 4-7/8" hub height, bypass connection at 12:00 position

At this point in time it's become very hard to find an off the shelf 68-72 water pump. The only one listed at RockAuto for example is the GMB 110-2908 (cast iron), which has the wrong shaft length, the bypass connection is in the late model location, and it appears to hit the harmonic balancer as well. If you want a correct 68-72 water pump you'll probably need to send one out to have it rebuilt, or buy a rebuilt unit from one of the AMC vendors who usually keep them on hand. They do have a core charge however.

Aluminum 73-up pumps are available from multiple supplies, and all appear to use the same basic GMB casting, except the Edelbrock pumps. The casting quality is a huge step up from the cast iron pump bodies, with larger passages and more concentric connections. Here's a rundown of those aluminum pumps:

GMB 110-1040AL ($28) - Standard replacement. 12 month / 12,000 mile warranty.

GMB 110-1040P ($45) - High performance, better bearings, better seal, better impeller. 12 month / 12,000 mile warranty.

Airtex AW3401H ($52) - High performance, better bearings, better seal, better impeller. Lifetime warranty.

Flowkooler 1781 ($93) - CNC billet 16 vane impeller with anodized coating, reduced impeller clearances. 4-13/16" hub height. 2 year warranty.

Milodon 16271 ($104) - High volume. 4-13/16" hub height. 180 day warranty.

Here's some comparison pics of a typical cast iron pump casting with the GMB aluminum casting, courtesy of one of the fsj sites. Based on this and the variety of available offerings I can't see any reason to use a cast iron water pump.




Edelbrock offers water pumps in both common hub heights, and therefore has the only 68-72 aluminum pump available. The same casting is used for both, so the only difference is in the hub height.

Edelbrock 8831 ($273) - 68-72 short pump

Edelbrock 8832 ($281) - 73-up long pump

Be very careful of the GMB aluminum pumps.  They appear very nice but break at higher rpms.  We have had several failures on these and only use them for Jeeps and grocery getter engines now.  The Edelbrocks are top notch but expensive.   Galvins has the pre 73 pumps new.  
Steve Brown

Algonac, Mi.

69 Ambassador sst 390

84 Grand Wagoneer

69 Cougar XR7

65 Fairlaine 500XL

79 F-350 Super Camper Special



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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/13/2019 at 10:33pm
What type of failure, and which GMB aluminum pump?
1968 AMX 390 / T5
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 69 ambassador 390 Quote  Post ReplyReply Direct Link To This Post Posted: May/13/2019 at 11:09pm
The casting fails on the nose where the bearing is.  It only happens when running high rpms and hard acceleration.  A customer lost two radiators.  The GMB is not as heavy in that area as the Edelbrocks are.  I would limit the GMB castings to stockish applications and definitely not on clutch fan installs as that puts a lot of weight on the end of the shaft.  Same customer put an iron pump on and no more issues.  The GM just doesn't have enough meat or reinforcing ribs in that area. 
 
Steve Brown

Algonac, Mi.

69 Ambassador sst 390

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69 Cougar XR7

65 Fairlaine 500XL

79 F-350 Super Camper Special



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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/14/2019 at 8:38am
Originally posted by 69 ambassador 390 69 ambassador 390 wrote:


The casting fails on the nose where the bearing is.  It only happens when running high rpms and hard acceleration.  A customer lost two radiators.  The GMB is not as heavy in that area as the Edelbrocks are.  I would limit the GMB castings to stockish applications and definitely not on clutch fan installs as that puts a lot of weight on the end of the shaft.  Same customer put an iron pump on and no more issues.  The GM just doesn't have enough meat or reinforcing ribs in that area. 
 


Good info... I expected a limitation with aluminum pumps, being that they are cast, and nothing done to beef up the snout. IMO the Edlebrock would be the best option for crank driven perposes. All the other aluminum variants seem to use the GMB casting.

Though, an electric pump seems to be one of the choices many strip racers opt for.

It is nice to see, as of recent, new iron pumps are available for the two variants. Will end up using my GMB aluminum one for emergency spare perposes. As it was a cheap option, that will work in finalizing my modified accessories installation, using the 73 on up pump.


Edited by 304-dude - May/14/2019 at 8:41am
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 mmaher94087 Quote  Post ReplyReply Direct Link To This Post Posted: May/14/2019 at 11:09am
The boys a MOPAR will tell of shearing the front off the pump with high horse power motors.  They recommended removing every other vane off the water pump impeller.  If one thinks about what's happening; it makes sense.  Engine revs quickly and the impeller in the pump tries to move water quickly.. water cannot be compressed.  Something breaks.
Mike
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