Thank you for the info...here is what little I can tell you, as the car came with a verbal history and little in the way of written build/repair/upgrade documentation.

I bought the car as-is and have no idea if the party who did the EFI/carb conversion changed out the thermostat, so I really have no idea about the thermostat rating. I have spent almost all of my worktime rebushing the parallel 4-bar rear suspension and the two front suspension bars. Likewise, I have not checked the timing, although I do have a good timing light and will do that this week. I did wonder if my timing might be too far advanced when I had a battery suddenly quit spinning the engine, but after posting a thread here on CC the vast majority of responders felt it was just a 4 year old battery that had run out of lifespan. I do have a very small battery in the car now (375CCA) and it starts better than it ever has.

The fan is operated manually by a toggle switch on the dash, not automatically switched by a temperature sensor. I do keep a keen eye on the temperature gauge and when the needle hits 200* I switch it on. I can start the car cold on a warm day and it will be up to 180* within 8-10 minutes. If I continue to let it idle the coolant temperature will continue to increase until I turn the fan on manually, then it cools down to around 185* and stays there until I get it out of the driveway. After that the temperature rise depends on how and where I drive it. The biggest problem is when I get into the center part of Houston where there are long periods of stop and go driving on the freeways...even with the fan on it gets close to 230* during those 45 minute stretches of stop and go traffic on a hot day.

I will do as you suggest, make sure I put a new 180* thermostat in and check the timing. Unless I can figure out how to do it easily right now, though, the shrouding will need to wait until I put in into the garage for winter storage.

I have reason to believe this vehicle started its life as a drag racing car and was converted to street trim in order to sell it...just too much in the way of race stuff on it...a welded thick-gauge aluminum fuel cell with foam blocks in it, Mallory fuel management (fuel pump/fuel filter) as well as Mallory Hy-Fire ignition components, the way the bumper hoops mount look like they were originally for push bars, that sort of thing. I was told that the huge Griffin radiator was installed while it was in its current "street trim" condition to address an overheating issue. The car is very minimalistic in orientation, no convenience items like power brakes/steering, heater, just a drivetrain and an alternator. Perhaps temperature management was not an issue if it was originally purpose built for only driving 1/4 mile at a time.

Thank you for the advice...as I said, I shall change out the thermostat and check the timing and see if the that makes a noticable difference (will check the opening temperature on the thermostat before I install it, too).

Cheers!!

Dugly :cool:

NAJA289, look me up during the Monteray weekend, I'll be at the Seascape, looks like we have the same ride. I put in a custom made radiator from Ron Davis, no cooling issues what so ever.

I'm a believer, used WW + water for years. Plenty of good suggestions here, one I haven't seen is what size alternator you are using. When sitting still at idle the fan can slow down with a weak alternator, you need ~95 amps in one of these cars to keep that fan turning full speed. I upgraded and the difference was surprising. Good luck.

Any size radiator will work if you pull enough air over the coils. My big motor over heated until i got a fan from a Lincoln Mark VIII. it comes with a shroud and pulls major amps so expect to upgrade your alternator to 100 amp. I tried Water Wetter and every other gimmick including 2 other fan setups until I got the Lincoln fan. I have cruised it in D.C. in 100 degree weather with no problems. When the fan kicks on, it drops the temp like a hammer. One issue though...keep anyone under 60 pounds away from the opening for the radiator!!!!

We just had a rework of the cooling system as the fan would not turn on by itself as designed. Found the fan had aged and took near 40 amps to turn it.

To replace the fan, the radiator was pulled. Hence we needed to redue the collant. Used to run over 200 degree ( 205 - 208 ).

As it turned out, we run about 200 degrees in the 96 degree heat with 50/50 and 1 bottle of WW.

That is good for a stop light.

So it works for us.

Just weighing in.

:D :D

Things to check: thermostat & cap, fan turning in the correct direction, standard pulley sizes (no undersized crank pulley/oversized waterpump pulley) and on a small block, water pump rotation in the correct direction.

If these are OK, nearly always overheating at a stop indicates an air bubble.

Most Cobra owners go into denial about this.

It is the cause in a large number of these cases....

Your radiator sounds big enough.

Just sayin,

Tom

Another thing for you guys with idle speed cooling issues to consider is idle timing. If you have a vacuum advance and it's hooked up as ported and idles at 8-14 deg advance or so, you're burning a lot of extra fuel to keep your catalytic converter up to temp (which you should not have in the first place).

On the 1978 Chrysler 360, there's a thermostatic vacuum switch (I'm sure many other cars have one as well, but this is one I read all of the emissions chapter on)in the intake manifold's water passage that can switch your vacuum from ported to manifold at somewhere near 200 deg. If you can't be convinced by the recent vacuum advance thread to run your vacuum advance on the manifold, add this little emission device, and when you're about to overheat, it'll give you a few more degrees, upping the idle speed 300 rpm and running cooler.

I've tried water wetter, and it does drop the temp. Just poured it in a 50/50 mix, and within minutes saw the temp gauge drop ten degrees. It stayed ten degrees cooler under most conditions after that.

It did nothing to prevent an overheating issue caused by the e-fan not turning on. Most overheat issues are a lack of airflow thru the core - and overheating is the direct result. Regardless of what I thought was working correctly, it still boiled down to no air, no cooling.

Once I fixed that, the longer term result was less satisfactory. Because of the overheating, the head gasket was weakened, and that led to the coolant - being wetter - creeping thru some warpage more easily and voila, dumping into the crankcase. BUT - you couldn't see antifreeze in the oil. That's because water wetter allows stuff to mix thoroughly. I changed the oil three times to stop a lifter collapse problem when it finally occurred to me that the engine had consumed two gallons of antifreeze mix - but I had never seen any evidence of it I could recognize, until I realized I was pulling 9 quart oil changes.

If you're having overheat issues, water wetter isn't the answer. Fixing the lack of heat transfer is. The typical causes with the radiator are air bypassing the fan and/or not going thru the core, usually caused by no shroud or no fan. With coolant, the core itself is clogged, the t-stat fails shut, the water pump impeller isn't working, or working far too well.

"I knew for a fact" the coolant temp sensor couldn't be the problem - until I learned it was just exactly that, a temp sensor - not a fan switch. Temp sensors won't pull 12VDC and engage a relay, they send about 8-9VDC at 195. Fail. Don't "know" your part is working correctly, test it and be sure, especially when the previous attempts have failed. That's direct evidence an assumption is false and you're wandering in the rose garden.

I use it & it works. I have a 521 based on a 460 block & it hates hot weather. (anything 85 & over) Will get up to 230 in 2 stop signs or so. I added 4 bottles of water wetter & now it only gets up to 210 on a hot day. Will run at 180-190 when moving.

Surfactants like Water Wetter and Cool Ice is not a magic panacea for overheating. Take a look at what it is, and how it works.

Water forms a boundary layer on surfaces as it moves through the cooling system. Look at the meniscus in a glass of water or test tube. The boundary layer adheres to the metal surfaces, and moves slower than the rest of the fluid. It slows down the transfer of heat from a hot surface like the head into the coolant. By the same process, it also slows down the transfer of heat from the coolant to the radiator fins.

Surfactants break down the boundary layer and allow the heat (energy) to move from one place to another more easily. They can also eliminate the slow moving boundray layer. It will "pull" heat out of the heads and put it into the fluid. Then it will "push" heat out of the coolant and into the radiator fins, where it can dissipate into the atmosphere. Essentially, it makes the existing cooling system a little more efficient.

Where do most people put the sender for the temp gauge? In the engine outflow tract. That coolant will be carrying more heat (energy) than it did before, and make the gauge read hotter. If you want to know how well it works, put the sender in intake track, like just before the water pump. Or install a cylinder head temp gauge.

Benefits to be gained from a decreased cylinder head temp is a cooler intake charge, less detonation, more power, and increased efficiency. It will not make up for a bad tune, or a poorly designed cooling system.

Thanks for the suggestion, Tom. Here is what I did when I changed out the coolant...once I had the radiator as full as possible I capped the place into which I fill the radiator. It is clearly the highest point in the cooling system, standing well above the area where the thermostat is located. I ran the car up to temperature (felt the top hose to make sure hot coolant was making its way past the thermostat), then filled the system. I did this at least 3 times and got it to the point that there was no more room for coolant every time I would check it.

Then I jacked the front end up enough to set the tires on some ramps I have and proceeded to repeat the process described above. Only once would any coolant fit into the cooling sytem, after that the coolant level was consistently at the location where the radiator cap seals against the fitting (my Griffin radiator does not have the cap on the radiator)

Should I be doing anything else to make sure there are no bubbles in the cooling system?

Thanks...not in denial here, just looking for answers. Today I had the Cobra out about town and at one point the temp gauge read 210*. The ambient temp was about 95*, sure wish I had an infrared thermometer to measure the temperature of the asphalt!

I am pretty firmly convinced that adding shrouds to the side of the radiator will help, will start working on cardboard templates so I am ready when the car is put up for the winter.

Cheers!

Doug

If you have a compressor, get one of these: UView: Product Detail, makes filling a cooling system a snap and absolutely no air will be left in the system. It will also test the system for leaks.

I thought you said it ran hot? In my book HOT does not begin for another 20-30 degrees.

It is quite common for the temperature to reach 230* during the long, slow stop 'n' go freeway traffic in Houston...at times it can take 45 minutes to crawl only one mile. When that happens, I try to get to the "inside" lane so that if I blow a radiator hose I can get off the freeway, but then that initiates a "Safe-tow" process where the city will come and tow my car to a place off the freeway...for a huge fee, of course.

I agree...I do not worry about 210*...

Cheers!

Doug

A 50/50 mix with a 15psi cap will boil at about 265F...

I had no idea it was that high...perhaps I have nothing to worry about, I have never seen the needle get higher than 235*F, even in the worst of heavy traffic and high ambient temperatures.

How much would you suppose my 15/85 glycol/water mix with the Water Wetter affects the boiling point?

...I should have long ago apologized for the thread drift in my posts and do so now :eek: ...it is just that 3 days before the OP posted his question I had gone through the effort to replace my coolant mix using the Water Wetter and had not noticed any improvement, so this thread could not have come along at a better time or been more germane to what was going on with my Cobra!

My sincere thanks to all who have made suggestions!

Cheers!

Dugly :cool:

Here's another air pocket sucker for a bit less dough: Amazon.com: UVIEW 550500 AirLift II Economy Cooling System Refiller: Automotive

Dunno if it works but I just ordered one....

Antifreeze table
 

"How much would you suppose my 15/85 glycol/water mix with the Water Wetter affects the boiling point?"

This chart might help answer question

Antifreeze table

I used the water wetter in my Cobra and dropped 10 degrees. It actually runs too cold now when it's colder than 60 outside (runs about 165). In my 38 Chevy (blown 350 in a real small engine space) it came with Evans Coolant, which although does not make engine run cooler, it will never boil over. Lot of hot rod folks use it. I'm happy with either and both seem to help problem, depending on which way you want to go.

And this site has pressure/boiling point charts. (Note that they use absolute pressure, so a 15 psi cap will net 30 psi total.
Pressure and Boiling Points of Water