[Pontirag]

You can bet I didn't get that warning for clowning around. Kinda proud of it. Too bad you cant lock some idiots heals like in the good (bad?) old days. Its like our public education system around here anymore.

[engineer]

the comment I made about the need for a thermostat (coolant flow control) is backed up by an article in HHP FEb. 2008 on pag. 85 for those who need it in writing.

[twisted]

Just curious...and I have to admit, I skipped most of the post on the last page due to a lot of off the wall comments...

But, some people say that faster water movement does not mean that heat will be removed better, because the water has less time to draw in the heat, and less time to release the heat once in the radiator....? I think that was the basic concept?

But if this is true, then how can a higher CFM cooling fan on the radiator make such a huge differance in the heat exchange? You are increaseing the air flow.

Myself, I am far from a scientist, but I put in a large BeCool radiator, and a 1600 CFM electric fan, so I am seriously thinking of putting an electric water pump on the new motor going in, but not sure who to really beleive here.
I think for now I will stay with the stock water pump with the modifications.

[Pontirag]

Its not a matter of removing the heat from the water in the radiator part of the system. its more critical to remove heat from the engine as the water circulates through it. It must remove heat from the hot spots and yet maintain a proper and reasonable range of temperatures so that the engine operates efficiently and the radiator can remove enough heat from the water. removing heat from the water flowing thru the radiator is rearly the problem.

The question that must be answered is does the water do a sufficient job of removing the heat from the engine. As it is the engine that is over heating. not the water frlowing through the radiator. A cooling system the size of lake erie does not guarentee the ENGINE wont overheat. And as a matter of record most people will agree it is the engine that does overheat. High volume water pumps only pump a high volume of water. they do nothing else for the rest of the system

The term "SUFFICIENT" gets thrown around alot but it would be wrong to presume that anything above and beyond sufficient is a good or better thing. Just like with oil pumps. Too much pressure starts to cause problems in other parts of the system. No difference. If it is sufficient why not leave it alone. The fact is that what is sufficient for one set of circumstances may not be for another.

Typically most radiators do a fine job of removing heat as long as the water is in the readiator long enough to transfer the heat. Most drag racing vehicles can get away with a very small radiator as it only has to do a little work for a very short period of time. On the road is a whole nother story. cant design the system to operate at the extreams and then actually operate it in the average. You will be chasing shadows to correct problems.

Gota use a thermostadt if your going to run aluminium heads. You gotta keep the temps up with aluminum heads or you will blow gaskets.

Might consider some sort of switch for your electrical pump that alters the rpm's based on temp rather that a constant speed switch.

as for my statement above regarding the warnings I have recieved it was in response to an attempt by somebody to discredit my answers simply because I got those warnings. They're reply seems to have been removed so my response seems out of context. My apologies to OTHER readers of this thread.

[twisted]

Well both sides of this argument actually have a lot of strong points.

I think my tactic is going to be to run my stock water pump with the restrictor plate mod that george so kindly pointed me to a year ago.
Then if my engine is showing any cooling problems which I honestly doubt since it is a street application, then I will go to an electric and try it.

I can see the stock pump with my current radiator/fan combo being plenty though.

Thanks to everyone for this thread. While it got a bit heated <pun intended> it had a lot of good points, theories. suggestions, and information to really get someone thinking.

[Geoff]

One of the benefits of increasing water pump speed is that it also increases water pressure. In simple terms, you are trying to force more fluid through a restriction; the t'stat is the restriction in the coolant system which is why it is important to retain it; forcing more fluid through the same restriction increases pressure.
There can be & are localised hot spots within the engine, such as around the centre cylinders exh valves, where the temp is so high that the water flashes to steam. Steam contains air bubbles, & air is a very poor conductor of heat compared to water. The pressure increase from increasing pump speed helps to suppress air bubble size & quantity, which helps cooling.

[Region Warrior]

Originally Posted by 'ol Pinion head

Read something to the contrary, early in this thread. Can relate ALL '69-81 Pontiac V8 original GM waterpumps are not the same. The original "296" castings built for 301's & 265's had a low drag cast impeller. The impeller blades in these are shorter.

Have the original "296" waterpump from my '80 Turbo car, it crapped out at 35K miles (I had the alt belt too tight...DUHH). Over the years, I've been buying up & rebuilding original casting & dated '68-74 Pontiac waterpumps. Those are the date range most buyers have wanted. With the high point restoration of W72 T/A's getting more popular, will soon be offering late date "296"s.

Ok, all 350, 400, and 455's from 69-79 had the same replacement # from GM
265 and 301's were diff.

My turn.
Someone said a larger pulley spins the w/p faster.
Thats partly true.
Also depends on crank pulley size.

Non ac cars used a 7" crank pulley with a 8" wp pulley.
A/C cars used the opposite. 8" crk/7" wp.
The larger crk plly with smaller wp plly will spin the pump faster.

[dmac]

You can mount two 12 inch unshrouded electric fans diagonally that each flow 3000cfm and only draw 8 amps each for $105 each from summit. I run (street only) the meziere 40 gpm, a 7lb radiator cap and NO thermostat, three core oversized radiator from a full size GM car in my 69 firebird and it runs no hotter than 185 degrees. I have the pump and fans switched to start at 165 degrees. My son drives the car in California, so low temps aren't a problem. I have massive water flow through the radiator, and think that the more cool water you can run through the block the better the cooling. Common sense says that if you can get the water cooled off faster while its in the radiator, and send a greater volume of cooled water into the block, the cooler it will run.
I don't think you want to slow the flow through the radiator, because that slows the flow through the block, and slowing the water through the block just gets it hotter. You want the fastest flow that gives the radiator sufficient time to cool the coolant. Increasing airflow through the radiator to the maximum will have the greatest effect on cooling, The cooling capacity of the radiator is dependent on airflow- no airflow means no cooling. If you keep your coolant cool, and can circulate it as fast as it gets hot, you can't overheat. I think for some applications, you could run four of these fans if you wanted with variable fan speed. If your car is running hot, you need to first cool the water and next get it out of the block before it gets that hot. As far as a restrictor to increase pressure in the block, I think there is enough back pressure in my case in the radiator to fill any gas bubbles or hot spots. Whether you use an electric or mechanical pump is really irrelevant- both simply push water through the block at approximately the same volume, on average, considering higner volume from the electric at lower rpm, and vice versa.

[Pontirag]

Geoff pretty much summed it up. If I may make an addendum. The thermostadt is a restriction until it opens. Then as the system begins to work in unison pressure is determined by the cap. temp of ENGINE is determined by the thermostadt. Radiator cools down the water. pump produces flow.

Geoff also brings up a good point about the thermostadt being a restriction to flow on a system that has a high flow water pump. The engineers never intended the thermostadt to be a restriction but when you add a larger radiator at one end and a high flowing water pump and or increased rpm pulleys at the other end the the thermostadt does indeed become the restriction. More so if it is constantly closing when awash with a slug of lower temp water that causes it to close.

it is constantly opening and closing against not water temp as it should but against water pressure from the pump. It is designed to stay open constantly at a given water temp as dictated by the engineers. If it opens and closes constantly rather than open and stay open then you have a cycles of airation of coolant and overheating when it closes and over cooling when it opens which causes it to close again. This is hard on the physical strength of the radiator and heater core as the constant cycling also produces slugs of high pressure water that flex's the components at there weakest points repeatedly befor the radiator cap has time to open to relieve pressure. Once it (the cap)opens and dumps pressure/water then you have the added problem now of possibly not having enough coolant in the system to do its job. You may be able to tell if this is the case by CAREFULLY feeling the temp of the water spewing out of the cap. In a case I experienced, the water was barely even warm.

You must have a thermostadt. especially with aluminum parts and on the street or when you drive in winter. If you go with a higher VOLUME water pump then also go with a larger radiator and consider a set of pulleys that will reduce pump speed...especially if you built the engine to achieve higher rpm's. Before you do any of this stuff be sure the problem is not a fuel or ignition problem. Also this may sound silly but dont over fill your radiator either.

[ronaldrust]

I also have a 67 orginial water pump setup. As you know it has a dual plate setup. Is there anything critical about the clearance between the two plates?

[lust4speed]

There's more areas to watch with the earlier two plate system. Place both plates on the water pump housing and tap the back plate down to almost touching the impeller. On the newer assembly the plate can be tapped down to touching the impeller because the gasket will then supply the needed clearance. The two plate system has the plates in contact with the pump housing so you do need to keep about .050" clearance from the impeller.

Anywhere the plates touch each other, there should be full contact with no gaps. Not much hammering is required to true up the surfaces.

The next critical area is how far the plates set into the timing cover. The erosion of the cover will let the plates set too far to the rear and you will loose the good fit of the plate to the impeller. This is a great area for JB Weld. The idea is to rebuild the ledge on the timing cover so the front of the forward plate once again sits flush with the machined surface of the timing cover. You have work to do anywhere the plate doesn't sit level and you can push it back farther in.

As long as you have the JB Weld out, rebuild any area inside the timing cover that has been eaten away. Getting the back plate to sit flush and tight against the water channels helps as much as tightening up the clearance for the impeller. I had a friend that wouldn't spend the money on a new cover and I used four sets (4A & 4B tubes) of JB Weld reshaping the interior and gasket surfaces. The before and after temperatures on the project was a difference of 30° with no change in any other part of the system. Our local Route 66 cruise route is pretty much a 2-1/2 mile parking lot that over powers many cooling systems - and his engine won't climb over 175° around the stop-and-go circuit on a hundred degree day.

[ronaldrust]

thanks for the input. My plates are so loose that you can see light around the edges and the impeller is 1/4 inch from the impeller. Should I bang down the plate or pull the impeller off the shaft to fit?

Ron

[lust4speed]

Leave the impeller on the pump housing and tap the plate in closer using a circular motion around the center. If done correctly, the impeller will never be hit.

[ronaldrust]

I just purchased another water pump for my 67 GTO and it is a Bosch but has stamped vanes. The old one I took off had cast vanes. Can I used the stamped????? I see on the thread that people are dead set against them. I have hammered the plate close to the vanes so is that enough?

Ron

[v869tr6]

I installed a remote water pump in the lower hose and run a Flowcooler pump with a small pulley I got from the group purchase on this site.
http://www.prpracingproducts.com/cat...ter+Pumps.html
My car has never run so cool.

[ronaldrust]

can someone explain how the water flows in a two plate system that is in the 67 GTO water pump. I think it is also in the 66 GTO. I hammered the plate close to the vanes but am concerned that the spacing between the plates has also changed and could restrict how the water flows to the driver side port. I am getting ready to assemble.

Ron

[lust4speed]

Half the coolant goes to one side of the block and the other half to the other side. The passenger side had a somewhat normal looking round hole while the drivers side is very irregular. The ring area around the impeller should be equally divided between the two feeds. I'd estimate that there should be an 1/8" for each portion. Not a good picture, but I'll include it anyway. The shim is just set on there for some sort of idea on how deep the slot is. It's important that the plate sits tight on the timing cover, and that both plates fit together tightly along the outside edge. The coolant is pulled in from the center and slung outward by the impeller, and by equally sharing the available space, both heads will receive the same amount of coolant.

[ronaldrust]

Hi Mark,

thank you so much for the valuable input into my water circulation education. I have put the 67 gto back together under your advice. Fired her up today and on a short trip did not get above 160 degrees. Never had it that low before but the weather here in Delaware is cold (40 degrees) and not sure my thermostat is working. BUT have definitelly moved in the right direction. The final test must wait until this summer but I am confident that we have solved my heating problem. And yes I am putting in the heater valve. Good idea.

Thanks again.

Ron