Cool/Heat: One thing in common with flathead Fords...

[Warren Webb]

We have one thing in common with flathead Fords, especially Avanti's, overheating. I just got a thing from Bob Drake who provides lots of parts for Fords. His stuff is top quality reproductions and has now come out with a redesigned water pump for flatheads. He shows the old style impeller compared to his new style and the old one looks a lot like what we run in Studebakers. Now I don't know who makes the pumps for us but I thought a note about this here might be worth investigating. Not that we want to buy water pumps from a Ford guy, but the design theory, especially of the impeller & its ability to move more water (coolant). I know from my experience with flatheads that this has been a problem for years. Ones have tried cutting off every other blade on the pump thinking that the water is flowing too fast in order to cool properly. This though looks like a reasonable way of fixing a problem. If I'm correct Edelbrock has a pump for SBC's that have a similar impeller design. Check it out.

http://www.bobdrake.com/Categories2.aspx?Id=22efb4b7-07ca-4056-98fb-a54ef176aa13

[Dan Timberlake]

Hi Warren,

In days gone by such authoritative sources as Hot Rod magazine articles and even the Moroso catalog talked about coolant moving too fast to cool effectively.

I think in the last several years most sources have abandoned the logical sounding "too fast to cool" theory. Removing heat from a surface is actually not the same as creating the highest coolant temperature.
The description of the impeller improvements in your link are summed up as :"This offers twice the coolant flow of the original Ford units for a much cooler-running flathead."

Fast moving water strips off the "boundary layer" on the surface we are trying to cool and accomplishes forced convection, which is way faster than waiting for heat to crawl into the water via pure conduction.
This link has thermal conductivities of various substances in "furrin" units, not BTUs and lbs. Larger numbers = faster heat flow which is what we need.

http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

Water is a wimpy 0.58 ( I think 50/50 antifreeze is lower/worse) . Steel is almost 75X better, at 43. Cast iron is listed as 55. Aluminum is over 200. If the job is to simply "conduct" heat away from the combustion chamber, solid iron would be way better than stagnant, non-moving water. Air (held still, as in fiberglass insulation) is even worse than water at 0.024


An example given to me as a teenager by a kind. clever, practical dad of a friend was this. Bring a double scoop ice cream cone into the car ( non-air-conditioned in thosed days) and drive home. With the windows up you may be able to lick fast enuff to keep it from dripping. But open the windows, even when just driving thru neighborhood , the cone will melt so fast you will not be able to keep up. I only tried that once or twice.

One bad thing that //can// happen when a pump is going "too fast" for conditions is the pressure at the inlet gets too low, and the liquid boils, cavitating severely and reducing flow. Similar to 'vapor lock" that can strike a hot dead headed fuel system.

I think A high pressure radiator cap does more than just raise the boiling point of the bulk coolant. It raises the pressure at the pump inlet, keeping it pumping when things get hot.

[jclary]

While the ad spends a good bit touting the change in the impeller design, I noticed that it mentions that they have decreased the gap between the impeller and the casing by half. That little blurb alone, could be as important as any detail in the design. As with any impeller/gear pump, "slippage" is a critical factor. That is directly affected by the clearances between moving parts. That is why, on our Studebakers, I always emphasize using the thinnest possible gasket to seal the mating surfaces. I learned a long time ago, that making my own gasket with thick heavy-duty gasket material, is not very smart for the water pump. A thick gasket will do a great job in preventing leaks, but it will also increase the gap between the pump impeller and the back of the casing. The result is more "slippage" and less water flow, resulting in running hot.

[skyway]

Had to replace the WP in my then new-to-me 383 '66 Fury VIP in South Bend one May.
Bought the replacement at a shop somewheres south of Newman & Altman, and it had a turbine looking impeller.
Don't know about its spacing, but the car ran noticeably warmer until I got home and changed back to one with an old style
impeller.