Packard Forum Index » Post-War (1946-54)

Ok. Thanks.

Static timing is measured with the vacuum advance disconnected and plugged, right?

My original radiator is out of the car ('49 288 - non A.C) and available for pictures or measurements. What do you need?

Great! Thanks!

I need dimensions (HxWxL) and number of columns, fin spacing.

Interesting info on other brands water pumps. Most makes use the same pump with or without A/C, here are the ones we know of that differ.

53-62 Olds V8- A/C has bigger diam bearing, impeller has more vanes 8 vs 6

59-66 Buick A/C has fewer vanes

58-66 Plym 318 V8- A/C has smaller diam impeller

Inconsistent??? On the Buick and Plym there would be lower flow allowing the water to remain in the radiator longer and have a longer time to cool. On the other hand,. the water remains in the block longer giving it more time to heat up.
OLds seems to be backwards?? As far as I know none of these cars had an overheating problem, if there was one they would have changed something during the long span of coverage.

Big mystery to me??

I found a good reference on the effect of flow rate in the radiator:


What about laminar flow vs turbulent flow? When the flow rate slows down in the radiator, we may not have turbulent flow which reduces the thermal transfer. This is what a lot of the web sites that I am reading are saying. That flow rate in the radiator is more important than the time that the fluid remains there even if the temperature drop across the radiator is not as great.


The effect of heat transfer increases as the flow of coolant changes from laminar flow to turbulent flow. For laminar flow, heat can be transferred only by means of heat conduction from layer to layer. However, in turbulent flow, the mass transfer in the radial direction enables the heat to be transferred by both conduction and convection. As a result, the efficiency increases dramatically. The diagram below illustrates this concept.

Google "pressure drop across radiator affects cooling"



dc.engr.scu.edu/cmdoc/dg_doc/develop/design/cooling/31000005.htm

I would think that a faster flow would create a more turbulent condition inside the radiator. Does not square with the noted A/C water pumps having smaller impellers/ fewer vanes??

Many owners do not report cooling problems with the 48=54 cars so the factory design would likely be sufficient. In those cars that have a cooling problem it is my feeling that although "everything has been checked out" there is something that has been overlooked.

When using an infrared thermometer have you checked various areas of the block, especially around the rear cylinders where deposits build up inside? Have you had the cooling fluid analyzed for combustion gases?? Inexpensive kits are available Checked impeller clearance?? Timing/vac advance checked and double checked??

You are right. The "factory design" should be sufficient. So in my case, the radiator size was increased and as a result, the flow rate inside of the radiator went down. As the flow rate goes down, the fluid flow changes from turbulent flow to laminar flow. And we know that turbulent flow is better for thermal transfer. More heat is removed in turbulent flow than in laminar flow.

This situation is exacerbated at idle when the fluid flow is the slowest.

I am trying to get back to the factory design which is a thinner radiator with fewer columns so that I can get the flow rate up at idle.

In my case, engine has been rebuilt including new water distribution tube and new water pump. I have scanned the engine front to back.

I read the article on mold cooling. I also spoke to an automotive radiator design engineer. As I suspected, much of the downward flow is turbulent due to either the small cross section of the tubes or dimples that are in the tubes to create turbulence so it seems that laminar vs. turbulent flow may not be an issue.

Here's a good article to read:
overclockers.com/watercooling-physics-laminar-and-turbulent-flow/

Interestingly enough, I asked the supplier of the core about the tubes used in my project and he responded as follows:

We do stock both dimpled and smooth tubes but to my knowledge dimples tubes were primary used on some larger truck applications in the 80's and 90's. Smooth tubes were used in the core provided to you

Here's some pix and measures off my
49 23 series non A/C w/ 288.
It was running 3 years ago and did not overheat at idle in the driveway after 45 minutes, so should be correct.

Core is 20.5" x 26" x 3"

Hope it helps.

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