First Generation Firebird
Posted By: Bjorn Sefeldt water pump modification - 10/26/07 01:16 AM
I have personally done this, I got the tip from George K., since then John Wallace has added it to his website , and I have been asked to add it here!

Its a great water pump modification ,helps push more flow ....

http://www.wallaceracing.com/water-pump-mods.php
Posted By: berndude Re: water pump modification - 07/15/13 07:48 AM
Awesome Tip!!!!

I have been contemplating an electric water pump and cooling fans lately
Posted By: Dan68 Re: water pump modification - 08/24/13 08:21 PM
You think this may help my situation...heating up when I'm taching over 2400 RPMs cruising down the road?
Posted By: USMC_Ordy Re: water pump modification - 08/27/13 05:54 PM
It would make your pump more efficient and should help.
Posted By: Bjorn Sefeldt Re: water pump modification - 08/27/13 06:42 PM
it helped mine 'some'......until it went out...I replaced the broken with a FlowKooler...which works about the same as the old did with this modification
I had made several modifications , like adding in correct fillers , one missing rubber filler below , adding X plates,....removing an electric help pusher fan that prev owner installed (blocked more air), water pump mod.,making carb run a bit less lean, ...but biggest temp change was from new 3 core alum radiator. I started with a 'normal' running temp at 220-230F...now its 185-190F
Posted By: coilster Re: water pump modification - 05/02/14 06:12 AM
I did the mod to my car, help out a good amount. The PO had put in a 3 row radiator, now the temp. runs a little
to cool , may have to put in a hotter thermstat
Posted By: USMC_Ordy Re: water pump modification - 05/05/14 09:53 PM
Coilster, what temp thermostat do you have in there now? I had the same problem after doing mine and putting an alum 3 core rad and flowKooler pump on mine and I had a 160 stat and while it stayed around 180-190 in the summer heat, during the winter it didnt want to warm up, so I have to change my stat out to a 180 and try that. I am currently goingthrough a rebuild of the car, so that will have to wait until I get the car and engine all back together.
Posted By: coilster Re: water pump modification - 05/07/14 06:40 AM
Before I had to change the water pump out the car with the rad. would run about half way on the gauge. Than
sitting in traffic u would see it start going up if u didn't get the car moving. But now with the mod. to the water
pump and the rad. it stays at around 1/4 on the gauge. So I have been trying to do some tuning on the engine with the timing and carb. adjusting its coming around little by little. It runs 80% better than when I 1st got the car from how it ran. I think It maybe a 180 in there I'll have to pull it down and see.
Posted By: USMC_Ordy Re: water pump modification - 05/08/14 03:55 AM
Good luck in getting it set up, please post your final settings here so everyone else can use them if needed!
Posted By: 67redvert Re: water pump modification - 05/22/14 06:13 PM
I run a 180 thermostat now, before I couldn't run a 180 had a 160 in her. My temps with the 160 would be around 200 to 220, then I did the water pump mod and it helped out, I also found my after market cam needed to be advanced to 10 deg and now with the 180 thermostat it stays at around 180 to 200. the mod helped out.
I was running the cam at stock timing too 6 deg.
Posted By: wovenweb Re: water pump modification - 03/21/15 12:10 PM
Has anyone had a water pump retrofitted by Flowkooler? I noticed this option on their site($199). While it isn't cheap, it would allow me to use a date code correct pump on my car with significantly higher flow at low RPM than stock.
Posted By: ramair68 Re: water pump modification - 04/17/15 05:49 PM
Was going to do this, but it suggests that it only applies to the 11 bolt pumps. Thought all 1st gen pumps were 8 bolt? Mine is, so I guess I can't do this mod on mine.
Posted By: rohrt Re: water pump modification - 04/17/15 05:59 PM
Originally Posted By ramair68
Was going to do this, but it suggests that it only applies to the 11 bolt pumps. Thought all 1st gen pumps were 8 bolt? Mine is, so I guess I can't do this mod on mine.


You should have a stamped steel divider plate same as an 11 bolt pump.

I have seen some cast divider plates but I think they were on much earlier motors. I had one on my 64 Tempest. It was in bad shape so I just swapped it out for the stamp steel. I made the mode and that put it back in.



The most ideal way to close the gap is to repress the vanes down so it sits higher vs pounding down the divider plate. But since I do not have a press out comes the hammer.
Posted By: bigchief Re: water pump modification - 04/17/15 06:41 PM
Originally Posted By ramair68
Was going to do this, but it suggests that it only applies to the 11 bolt pumps. Thought all 1st gen pumps were 8 bolt? Mine is, so I guess I can't do this mod on mine.

It is a bit more complicated on a 8 bolt pump but still should be done. Problem is the rear plate on the 8 bolt is fitted inside the timing cover.
I lay both plates on the water pump and just get the impeller to touch the plate. Also make a few bends in the outer edge of the plate so it gets sandwiched in between the water pump and timing cover and doesn't move around. With the water pump gasket installed you have proper clearance.
Posted By: salmon38 Re: water pump modification - 04/17/15 07:34 PM
Originally Posted By bigchief
Originally Posted By ramair68
Was going to do this, but it suggests that it only applies to the 11 bolt pumps. Thought all 1st gen pumps were 8 bolt? Mine is, so I guess I can't do this mod on mine.

It is a bit more complicated on a 8 bolt pump but still should be done. Problem is the rear plate on the 8 bolt is fitted inside the timing cover.
I lay both plates on the water pump and just get the impeller to touch the plate. Also make a few bends in the outer edge of the plate so it gets sandwiched in between the water pump and timing cover and doesn't move around. With the water pump gasket installed you have proper clearance.


I've done the mods on a 8-bolt pump. Anything to move the plates closer to the impeller is helpful amd every improvement on these cooling systems is good since cooling is such a common issue.
Posted By: Barnstang Re: water pump modification - 01/12/18 06:07 PM
Resurrecting this thread. Searched a bit looking for other posts.

I put antifreeze in my 20+ year project for the first time in 20+ years. Leaked like a sieve from the pump. One of the divider plates had "fallen" btwn the pump and timing chain housing. So that's an easy fix....

I got the new steel divider plates but had assembled it before I came across the need to close up the gap btwn the impeller and the plate. So now that its back apart...

Pump is new 8 bolt with cast impeller. Summit Racing: GMB-130-2850 https://www.summitracing.com/parts/gmb-130-2850
Tried to find something at least a little better the local parts store, but not extravagant. If there's a better pump that wont break the bank I'm willing to entertain any suggestions...

It looks like a pretty big gap...over 1/8"

So the question is- Whats the best way to close up the gap without wrecking the plate(s)?

I found two really good youtube videos by scott34956, but he doesn't show HOW he closed the gap!

I'm pretty creative and detail oriented. Good with metal. Not afraid to try it, but thought I would ask here before going at it with a body hammer...my concern was making sure i could maintain the concave shape of the plate so the distance is consistent over the impeller blades from inside diameter to outside. Or at least as much as possible.

Posted By: salmon38 Re: water pump modification - 01/13/18 05:45 PM
I just put the plate on a sturdy flat surface (i.e. workbench) and gently tapped around the edge of the impeller hole (in the center of the plate) with a ball peen hammer until the gap was where I wanted it. The plate is fairly malleable.
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