FC aluminum water pump housing on a FB
Thread Starter
Joined: Jul 2008
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From: Chino Calif
Here you see an S4 WP main housing and a 79-85 GMB impeller. The gasket is an S4 and lines up perfectly on all but one hole; alt bracket hole location difference is clearly visible.
Differences in alt brackets themselves. Top is old school 3B/early R5 with external reg alt. Middle is typical FB with internal reg alt. Bottom is FC. Notice only the length increases for the FC as its bolt shifted lower in the WP.
gearhead-42 posted this nice pic of a new GMB.
Here is my OEM 3B/R5 heat shield stud with an oddball oversized 15mm nut I had lying around. A regular 14mm exhaust nut would also work perfect here.
Sorry I don't have any more pics of the WP fully assembled or installed. Maybe later.
Differences in alt brackets themselves. Top is old school 3B/early R5 with external reg alt. Middle is typical FB with internal reg alt. Bottom is FC. Notice only the length increases for the FC as its bolt shifted lower in the WP.
gearhead-42 posted this nice pic of a new GMB.
Here is my OEM 3B/R5 heat shield stud with an oddball oversized 15mm nut I had lying around. A regular 14mm exhaust nut would also work perfect here.
Sorry I don't have any more pics of the WP fully assembled or installed. Maybe later.
I will use that "special bolt" from the front iron and mount my standard FB alt bracket!!
For you guys that are thinking... "why is he fussing over only 14 pounds"!!!??? I have pulled out over 140 pounds in the last couple of months and still have many pounds to go!!!
On my lightweight autocross car, I REALLY felt those 140 pounds gone!!!
I plan on doing more mods and hopefully I will be soon down to 1900##
Congrats on finding the right stud! Yes it should be 10mm x 1.5 You can test it with an exhaust nut. Also take it with you when you get a tap to triple check that it's correct.
An FB gasket should work. Check how it will seal around the FC waterpump though.
An FB gasket should work. Check how it will seal around the FC waterpump though.
Joined: Mar 2001
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From: https://www2.mazda.com/en/100th/
i was actually thinking about putting my alternator where the airpump used to be, it doesnt save any weight, but it does move the 14lbs from up high to the right side which is really light
1900? thats LIGHT...
This is the GMB impeller, the part that moves the water, it's stamped steel (not aluminum) and doesn't flow as well as the stock cast piece.
This photo was originally posted in this thread started by trochoid in 2004
https://www.rx7club.com/showthread.p...r+pump+housing
This photo was originally posted in this thread started by trochoid in 2004
https://www.rx7club.com/showthread.p...r+pump+housing
Yep, it's not quite as good, but if you're running NA, it's good enough.
I do remember that thread. I referenced it before I experimented on my GMB. By the way, what's the green stuff? Always wondered but never asked.
I do remember that thread. I referenced it before I experimented on my GMB. By the way, what's the green stuff? Always wondered but never asked.
This is the GMB impeller, the part that moves the water, it's stamped steel (not aluminum) and doesn't flow as well as the stock cast piece.
This photo was originally posted in this thread started by trochoid in 2004
https://www.rx7club.com/showthread.p...r+pump+housing
This photo was originally posted in this thread started by trochoid in 2004
https://www.rx7club.com/showthread.p...r+pump+housing
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Joined: Jun 2004
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From: Grand Rapids Michigan
WHat do you think the weight difference between a cast iron and an aluminum pump??
I have not bought the pump yet, just modifying the housing. Guess I can do the mods and put an aluminum one on.
Kentetsu, do you just tap a hole in the FC housing for the 1st gen water pump??
Also, any other leads on how to get one of these GMB aluminum pumps??
I have not bought the pump yet, just modifying the housing. Guess I can do the mods and put an aluminum one on.
Kentetsu, do you just tap a hole in the FC housing for the 1st gen water pump??
Also, any other leads on how to get one of these GMB aluminum pumps??
I didn't drill/tap any holes when I mounted the the fb pump. Not all of the holes lined up, but with a bead of sealant to go along with the gasket it seemed to be more than enough to work...
Thread Starter
Joined: Jul 2008
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From: Chino Calif
I think the iron pump weighed about 6 Lbs, but I'm not sure on that. The aluminum pump weighs about as much as a can of beer.
I didn't drill/tap any holes when I mounted the the fb pump. Not all of the holes lined up, but with a bead of sealant to go along with the gasket it seemed to be more than enough to work...
I didn't drill/tap any holes when I mounted the the fb pump. Not all of the holes lined up, but with a bead of sealant to go along with the gasket it seemed to be more than enough to work...
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From: Grand Rapids Michigan
No, I didn't tap anything. I don't remember what hole I used, but it was an existing one. I'm sure I'll forget, but I'll try to grab some photos when I get home tonight (damn, just remembered I was supposed to measure the Bilsteins for Billy over a week ago too!). Guess I'd better get to work when I get home.
Joined: May 2002
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From: Ottawa, Soviet Canuckistan
Lots of great info and pictures, looks like another thread for the archives!
And yet another thing to add to the checklist of stuff to do on my S3... damn that list gets long if you aren't constantly hacking away at it!
Jon
And yet another thing to add to the checklist of stuff to do on my S3... damn that list gets long if you aren't constantly hacking away at it!
Jon
Thread Starter
Joined: Jul 2008
Posts: 1,671
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From: Chino Calif
No, I didn't tap anything. I don't remember what hole I used, but it was an existing one. I'm sure I'll forget, but I'll try to grab some photos when I get home tonight (damn, just remembered I was supposed to measure the Bilsteins for Billy over a week ago too!). Guess I'd better get to work when I get home.
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Joined: Jun 2004
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From: Grand Rapids Michigan
Okay, life hit me in the face as soon as I got home from work last night, so I forgot yet again. 
I'm writing myself a note right now...
btw, you going to DGRR or Mitty this year?
I'm writing myself a note right now...
btw, you going to DGRR or Mitty this year?
exactly what i did on the 74 engine, tapped the front side for a bolt and filled the back side with rtv. and i agree, this is definitely archive worthy.
Thread Starter
Joined: Jul 2008
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From: Chino Calif
Is there a readily available gasket for the housing to block?
Examining it, I think I'm just going to use hi-tack on the wp paper gasket and go. In my experiance RTV doesn't work well with a paper gasket.
Examining it, I think I'm just going to use hi-tack on the wp paper gasket and go. In my experiance RTV doesn't work well with a paper gasket.
Because the blades of the GMB impeller are straight(flat), and smaller, than the stock cast piece. Some things need physical testing, this is not one of them
Have you ever seen a boat propeller with flat blades ? Do you need to ride in the square car with square wheels to know it's not good in more ways than one?
Jeff, you have to ask trochoid about the green stuff, it's his photo.
Maybe it's some transparent material he used to trace gaskets.
I liked his idea of swapping the impeller, too bad it didn't work. There has to be a way to do it, GMB presses theirs on, but I guess they can press against the shaft to get it on there, maybe press the shaft out of the pump from back to front? I don't have a press, or experience with a press, maybe trochoid or someone can give it another shot. A cast aluminum impeller would be cool, I'm guessing that's what the MFR pumps have, a pic of one would be nice if anyone had one...
Have you ever seen a boat propeller with flat blades ? Do you need to ride in the square car with square wheels to know it's not good in more ways than one?
Jeff, you have to ask trochoid about the green stuff, it's his photo.
Maybe it's some transparent material he used to trace gaskets.
I liked his idea of swapping the impeller, too bad it didn't work. There has to be a way to do it, GMB presses theirs on, but I guess they can press against the shaft to get it on there, maybe press the shaft out of the pump from back to front? I don't have a press, or experience with a press, maybe trochoid or someone can give it another shot. A cast aluminum impeller would be cool, I'm guessing that's what the MFR pumps have, a pic of one would be nice if anyone had one...
Thread Starter
Joined: Jul 2008
Posts: 1,671
Likes: 9
From: Chino Calif
Because the blades of the GMB impeller are straight(flat), and smaller, than the stock cast piece. Some things need physical testing, this is not one of them
Have you ever seen a boat propeller with flat blades ? Do you need to ride in the square car with square wheels to know it's not good in more ways than one?
Jeff, you have to ask trochoid about the green stuff, it's his photo.
Maybe it's some transparent material he used to trace gaskets.
I liked his idea of swapping the impeller, too bad it didn't work. There has to be a way to do it, GMB presses theirs on, but I guess they can press against the shaft to get it on there, maybe press the shaft out of the pump from back to front? I don't have a press, or experience with a press, maybe trochoid or someone can give it another shot. A cast aluminum impeller would be cool, I'm guessing that's what the MFR pumps have, a pic of one would be nice if anyone had one...
Have you ever seen a boat propeller with flat blades ? Do you need to ride in the square car with square wheels to know it's not good in more ways than one?
Jeff, you have to ask trochoid about the green stuff, it's his photo.
Maybe it's some transparent material he used to trace gaskets.
I liked his idea of swapping the impeller, too bad it didn't work. There has to be a way to do it, GMB presses theirs on, but I guess they can press against the shaft to get it on there, maybe press the shaft out of the pump from back to front? I don't have a press, or experience with a press, maybe trochoid or someone can give it another shot. A cast aluminum impeller would be cool, I'm guessing that's what the MFR pumps have, a pic of one would be nice if anyone had one...
Heck, I don't know why I am even worrying about an alternator bracket..... I don't even run an alternator!!!
Joined: Mar 2001
Posts: 31,833
Likes: 3,232
From: https://www2.mazda.com/en/100th/
Because the blades of the GMB impeller are straight(flat), and smaller, than the stock cast piece. Some things need physical testing, this is not one of them
Have you ever seen a boat propeller with flat blades ? Do you need to ride in the square car with square wheels to know it's not good in more ways than one?
Jeff, you have to ask trochoid about the green stuff, it's his photo.
Maybe it's some transparent material he used to trace gaskets.
I liked his idea of swapping the impeller, too bad it didn't work. There has to be a way to do it, GMB presses theirs on, but I guess they can press against the shaft to get it on there, maybe press the shaft out of the pump from back to front? I don't have a press, or experience with a press, maybe trochoid or someone can give it another shot. A cast aluminum impeller would be cool, I'm guessing that's what the MFR pumps have, a pic of one would be nice if anyone had one...
Have you ever seen a boat propeller with flat blades ? Do you need to ride in the square car with square wheels to know it's not good in more ways than one?
Jeff, you have to ask trochoid about the green stuff, it's his photo.
Maybe it's some transparent material he used to trace gaskets.
I liked his idea of swapping the impeller, too bad it didn't work. There has to be a way to do it, GMB presses theirs on, but I guess they can press against the shaft to get it on there, maybe press the shaft out of the pump from back to front? I don't have a press, or experience with a press, maybe trochoid or someone can give it another shot. A cast aluminum impeller would be cool, I'm guessing that's what the MFR pumps have, a pic of one would be nice if anyone had one...
which version is this?????
Some of you may have seen my 13b installation in a Porsche 968, which I did last summer. We needed a water filler neck, because the Porsche radiator did not have one, so we used a 2nd gen water pump housing which I had. However, I have no idea which version it is - I was not aware of the variation. Can anyone tell me which version this is? Photos of the finished installation on page 7 of my Cardomain page.
About three years ago we installed a ported 13b (4 port) in a 1979 RX-7, which my friend Steve Roberts bought new. He had been using it for navigation rallies, but decided he wanted to go thrashing about in the woods in more serious rallies. We installed an aluminum GMB water pump, and he has been thrashing the engine pretty hard for a couple of seasons, running with a dual belt setup, so far no problem with the pump. He figures he is getting about 250 hp from the engine.
About three years ago we installed a ported 13b (4 port) in a 1979 RX-7, which my friend Steve Roberts bought new. He had been using it for navigation rallies, but decided he wanted to go thrashing about in the woods in more serious rallies. We installed an aluminum GMB water pump, and he has been thrashing the engine pretty hard for a couple of seasons, running with a dual belt setup, so far no problem with the pump. He figures he is getting about 250 hp from the engine.
Engine on left appears to have a very stock looking complete S4 NA waterpump.
Engine on right has a 1st gen cast iron WP but difficult to tell whether the impeller housing is GMB or stock cast iron.
Engine on right has a 1st gen cast iron WP but difficult to tell whether the impeller housing is GMB or stock cast iron.
Oh hey you see that little stud at the base of your red front plate? That is the stud I was talking about earlier in this thread. That stud makes it easy to swap to an aluminum GMB impeller on an S4 NA aluminum waterpump housing. You have one right there in that picture!
Thread Starter
Joined: Jul 2008
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From: Chino Calif
Oh hey you see that little stud at the base of your red front plate? That is the stud I was talking about earlier in this thread. That stud makes it easy to swap to an aluminum GMB impeller on an S4 NA aluminum waterpump housing. You have one right there in that picture!
Thread Starter
Joined: Jul 2008
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From: Chino Calif
OK OK OK.... here is the final weight savings between a FB cast iron pump housing and a cast iron water pump VS. an FC aluminum waterpump housing and an FB aluminum GMB (Japan) water pump.............
8.17 pound difference!!!!
Total cast iron FB package 13.26 pounds
Hydrid FB alum housing and FB alum pump 5.59 pounds
Is it worth it for me???? YES!!! To lose that much weight that high up....
Is it worth it to 95% of the rest of the 1st gen' er's.... I doubt it!!!!
What are your thoughts????
8.17 pound difference!!!!
Total cast iron FB package 13.26 pounds
Hydrid FB alum housing and FB alum pump 5.59 pounds
Is it worth it for me???? YES!!! To lose that much weight that high up....
Is it worth it to 95% of the rest of the 1st gen' er's.... I doubt it!!!!
What are your thoughts????