Yeah, I know it is a perennial problem, but I had my first experience with overheating in traffic yesterday. Never had a problem before, but I was in very slow stop & go for about an hour on my way to cruise night. It was about 80 degrees outside... not really hot, but the traffic was bad enough that the car was stopped most of the time. Maxed out the factory temp gauge. I have a mechanical gauge in the bypass line, which indicated around 210. It normally reads about 20 degrees cooler than the manifold, but of course I wasn't able to get out and check the temp with an IR gauge.

As the engine kept getting hotter, I popped the rear-opening hood to increase the air flow. As temps rose further, I turned on the heater. Finally, I started turning off the engine when the car wasn't moving. In hindsight, turning off the engine was probably a bad idea, huh? It didn't boil-over that I could tell. I knew the engine was hot because it dieseled when I shut it off... it has never done that before. One thing I did NOT do was rev the engine a little, which might have helped move more air and water around... my idle is set pretty low. Once the car was moving steadily again, the temps settled right down into normal range, and everything ran fine. No dieseling when I finally parked.

My engine is a fresh 292 (2Kmi), decked block, 113 heads milled for 9:1 SCR, Mummert 265 cam, Mallory unilite (mechanical only), 12 deg. BTDC @ idle. Runs very strong. I have a 6 bladed fan, "normal" water pump and pulley, and use a recovery tank. The level was low when I got to cruise night. It may have been low to start with, I didn't check. I'm running just distilled water with radiator relief. I know that there are things I can do to increase cooling... I'm considering getting an electric pusher fan. I've heard of installing a modified heavy duty big block fan & thermal clutch. But this experience got me second guessing my actions yesterday...

So, what do you guys do when you get stuck in traffic and the water temp heads skyward? Do you wait for the cloud of steam and then pull over?

Do you have any temperature reducer in the water? I would add some 40 Below or something like it. Antifreeze has a higher boiling point than water but the additives help. I think you may have just stressed your cooling system on the first outing. Stop and go traffic will do it every time. Having the water level down even a little can cause changes in behavior. Also, I bet it you had brought your RPM up to 1500 or higher it would have helped. If the idle is correct it should be ok. Just make sure you are full of water next time and see what happens. Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

I would definitely use a 50/50 mix of antifreeze and distilled water. Glycol based coolants were originally developed in part, to allow designers to use smaller (area) radiators on aircraft engines. The smaller and thus more aerodynamic radiators exploited the fact that ethylene glycol conducted heat significantly better than water alone. As mentioned above, briefly revving the engine in neutral would have probably helped to increase circulation of both air and coolant. Shutting off the engine while over heated is an invitation to more problems. That should be avoided if possible. Over all though, I wouldn't fret about it too much. Iron motors are generally pretty tolerant of temperature but they aren't unbreakable. Install a proper mixture of antifreeze + distilled water and keep cruising.

Do you have the 1” spacer in place behind the water pump? If so, then removing the ‘T-Bird’ specific spacer will improve the water flow at low rpms. The water pump pulley will need to be moved back forward that missing one inch to correct for the belt alignment to compensate for the ‘removed’ spacer.

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Another item that helps is to put a restrictor in the bypass line between the thermostat housing and the water pump. An eighth inch hole in the restrictor will suffice for that.

Lorena, Texas (South of Waco)

[quote][b]gekko13 "ethylene glycol conducted heat significantly better than water alone"

Do you have a reference source for that statement? Everything I have ever read re: coolant efficiency has labeled water as the best.

6 VOLTS/POS. GRD. NW INDIANA

I assume you thoroughly cleaned out the waterjacket passages in the block during rebuild? Did you also test the thermostat before installation? Even a new one can be defective/sticky. The CASCO waterpump with blade extensions is another option, as it is proven/tested to pump more coolant. A fan clutch would likely help at idle speeds only if you installed an undersized pump pulley. A modified engine usually means the radiator needs to be in top condition or upgraded.

6 VOLTS/POS. GRD. NW INDIANA

Daniel, I should have qualified the use of "better". Strictly speaking, pure H2O is an excellent "cooling fluid" but it becomes more efficacious as an engine coolant with the addition of ethylene glycol or other similar materials. Not only does it inhibit freeze damage to the water jackets and cylinder heads, it raises the boiling point significantly. Even under pressure, water boils at a lower temperature and steam is a poor coolant. Steam pockets can be a real problem in liquid cooled engines and anything to avoid that is deemed desirable. Now, because a 50/50 glycol coolant mixture can safely function at higher temperatures, other components such as heat exchangers can be sized accordingly- usually smaller and less drag producing- without jeopardizing engine life. BTW, back in the day (way before my time), aircraft manuals commonly referred to coolant radiators as "Prestone coolers". Sound familiar? But you caught me. I made an overly simple statement on a complex and multi-faceted subject. Sorry for the confusion.

This chart shows how the usual anti-freeze mixtures change the boiling point most of us don't get too terrified until the rascal boils over.



The use of a large flow capacity thermostat can help a t-bird a good bit more than a standard engine (without the pump spacer) so make sure you check that out. The "high flow" t-stat sold by Mr Gasket for a big block MOPAR will help. The flow restrictor in the bypass hose (mentioned by Ted) just about always shows an improvement in water flow to the radiator. Use a brass 3/8 nominal size pipe plug with a 1/8 - 3/16 orfice drilled through it. Insert in the short hose under the thermostat housing - otherwise the bypass is 5/8 tube "short citcuit" for hot water.

 
 Steve Metzger       Tucson, Arizona

I am using the Mr Gasket thermostat, and yes I tested it before I installed it. I've read about the flow restrictor in the bypass line... right now, that is where I have my mechanical temp sender located. I have reason to believe that there may be reverse flow in that line at idle, because it measures 20 degrees cooler than the manifold using an IR thermometer. This is another good reason to install an orofice.

I have avoided ethylene glycol because I've read that pure water actually removes heat better per unit volume (higher specific heat) than anti-freeze, even though it boils at a lower temperature. I will try to look up a reference and repost.

The additives I mentioned like "40 Below" are a lubricant and cooling additive for systems not using glycol. They have no affect that I've seen to antifreeze filled systems. Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire