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Kaylah 08-20-2003 01:35 PM

Water Pump Question
I've read some specs on a handful of after-market water pumps. Since I'm in "project mode", I want to replace the 351C stock pump before the weather starts getting cold.

Regarding the higer flowing pumps made by Milodon and Edelbrock, both claim that the pumps will circulate 20-30% better than OE pumps, which would make me assume that circulation will improve and they will cool better. I like the Edelbrock because it also has roller bearings which will enable it to hold up under stress a lot better. But both of these pumps are noticeably more expensive than an OE.

Question 1: Do they cool better and provide better circulation?

Question 2: Both offer cast and aluminum models, which is better suited for a non-racing application.

Question 3: Are either of these pumps worth the extra cost? The Miloden is somewhere around $90 and the Edelbrock is about $160.

Question 4: Having better cooling capability is one of my priority upgrading goals. I have a number of other cooling system modifications that I am going to install. Which pump will serve the purpose better, an OE pump or the "Hi-Flo"? PS - even if its small increments, this matters.


gt2betubbed 08-20-2003 02:47 PM

Hey Kay, I've heard both good and bad about Hi Flow water pumps, but more good than bad. Some say that the higher flow can cause pockets in the head where the water may get stuck for a prolonged time and cause a hot spot. I don't know how true it is, but I've always used Hi Flo pumps without a problem. To answer your questions:

1. They are supposed to.

2. Either one is suitable so go with your choice.

3. I use cheap ones out of Summit, or the cheapest (new) I can find at the time. So any extra cost is too much in my mind (said it before, cheap bastard).

4. I would go with the Hi-Flo, it really should be the better of the two.

Kaylah 08-20-2003 03:30 PM


Yes, Summit is where I got those prices from. I believe the Milodon is the cheapest one, so I'll go with that. Ohhh but I missed a deal on eBay...before I knew it, a new in box Weiand for a 351C was gone at a measley $64.00.

gt2betubbed 08-20-2003 03:43 PM

I hate it when that happens. It seems like good deals come around either when I don't need them, or when I'm not looking..

DoubleVision 08-20-2003 03:43 PM

Air pockets are gonna form regardless of the water pump, the irregular casting on the inside of the head causes this and makes these impossible to get out. the small block chevy is bad about forming air pockets in the heads, especially around the intake ports.

johnsongrass1 08-20-2003 03:56 PM

In the summit catalog you will find the plates that rivet or bolt onto the back of the impeller to provide more area to propel water. If you want to take the pump apart(5-6 bolts to gain access to the impeller)and attach the plate you can make your self a high flow water pump. That's all there is to a generic water pump. some companies who charge really high prices for pumps actually mill the pump cover to do the same thing as the 5$ plates you can do yourself. Sometimes the larger companies will also install larger bearings as well. If you are a street runner than I gotta recomend the above.

4 Jaw Chuck 08-20-2003 04:08 PM

I make my own "high flow" pumps, much of the difference is in the impeller design. If you look closely at your old pump and did a dry install with some plumbing putty stuck to a impeller blade you might find that the impeller is more than 0.050" away from the casting in the block. The reason why they do this is so if the bearings fail the impeller blades won't strike the block casting. Only problem is you need close clearances for the pump to move water efficiently, I always move the impeller out on the shaft to get 0.005"-0.010" clearance at the impeller. This makes a huge difference to the volume and pressure the pump is capable of.

As for how to make you own "high volume" pump you will need to find an old impeller that has cast vanes with the curvature to the impeller, most of the ones I see today are the sheetmetal straight vane type. These are inferior in every respect but cost. Set them close to the block and voila, "high flow" pump.

I know I know, the aftermarket ones have larger passages etc.etc.etc. but honestly if you set the pump up right with nice tight clearances they will perform about the same. It's getting harder to find these old impellers now, I grab every one I find in the junkyard. Keep your eyes peeled, they are out there.

As for the impeller hitting the casting...if your letting water pumps go to the point where bearings are need to find a different hobby.

They really aren't necessary for the street anyway Kaylah unless your running a supercharger or a turbo. Save your money for something that will make a difference in performance.

gt2betubbed 08-20-2003 04:36 PM


Mikey123 08-20-2003 04:44 PM

i know this sounds stupid but most water pumps ive seen that are belt driven ( oem belts and pullys ) allready move way more water than nescessary and usually need t. stat to slow the flow down so that the water stays in engine long enough to dissapate heat out of heads and cyls. the only time ive truly seen the need for any type of high flow w pump was either with underdrive pulleys or electric motor driven stuff and if you actually dont need the extra flow its just gona rob power, i know it seems petty but even 1 % of power waisted having to drive accessories or internal engine componets that are unnedded is just waisting power and most anything thats advertising 25% more output is usually gona need some sort of extra input to run it. just another view to add to the growing collection. see ya Mikey

wheel-7 08-22-2003 09:12 PM

Hi Flow pumps
Hi K
I put a aluminum " Flow Kooler " water pump on my 53 Stude coupe. The coupe has a 351-W instead of the Cleveland as you have. It helped a good deal on cooling. The temp. drop was about 20 degrees. It weighs about six lbs. less then the stock cast iron unit I took off. I think it cost me about $ 80.00 from Summit ? Hope this helps

5-7heaven 08-22-2003 09:29 PM

:cool: howziit guys!

i installed a new $20 NAPA long water pump on my 325HP BBC 454. with flexfan, recored OEM camaro radiator and no fan shroud, it cooled my '56 truck to 170*/175*...NEVER over 200*

i had to kiss my cheap pump goodbye, 'cause i'm installing a 6-71 supercharger(blower belt clearance).

i hope this used WEIAND aluminum pump can do as good as my NAPA pump.:rolleyes:

brief madness 08-22-2003 09:35 PM

Not quite a 351C, but I have a warmed over 302 which never ran over 190 degrees. I have a Crane roller cam, roller rockers, 600 Holley, full length headers, MSD ignition, etc. I use a stock water pump (which has a backing plate already installed) from Kragen, a four row radiator, 160 degree thermostat, 8 quart oil pan with high volume oil pump, flex fan, no fan clutch and no shroud. It has never run above 190 degrees, highway or stop and go in rush hour. Just something to think about.

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