Over-Heating 67 GT500

[Jakobs67gt500]

Hi Shelby'ers

Greetings from Greece - from Jakob & #1738
We have presently around 90 F.
My car is running hot, particularly in traffic.
when switching it off, the coolant is overflowing, and the car continue to self-ignite for 10-20 seconds.
I have the original radiator, original fan blade C6FOF-E and fan clutch https://gmb.net/product/930-2300/
We locked the fan clutch, and there was a small improvement but not enough.

I consider to order the https://usradiator.com/cores optima flow 4 rows. The car is manual.
I will very much appreciate any guidance you can give me, if I am on the right path.
There may also be a fan blade better suited (although this is the original)

Next step is to pull the heads and check if engine block and heads are aligned.
Engine is restored and has standard bore.

Many thanks for kind assistance
Best regards
Jakob

[Rickmustang]

Lots to check before tearing into the engine. What coolant are you running? How's the timing operating? Running a fan shroud?

[shelbydoug]

First, you need to scientifically verify the operating temperature of the coolant.

You need to be aware that there is only one temperature sender that makes the temperature gauge in the car read accurately.

That is the original AUTOLITE/MOTORCRAFT.

None of the current aftermarket senders read correctly.



The gauge should read in the middle of the scale with the correct sender. The aftermarket senders will make it read way up to the right on the gauge, 3/4 or more to the right. That is incorrect. Those are the wrong senders.


BB in Mustangs always are hot and more times then not, are difficult to restart hot unless you let it sit for 20-30 minutes. It is just the nature of the beast.

If you are running in the 100° Greek summers, I don't think that there is a lot that you can do about it. The engine just takes up too much room in the engine compartment to get adequate air circulation around it.


Several things that you can do that might help. Check for fuel peculating through the carburetors on a hot engine that you just shut off. The heat will rise out of the engine and boil the fuel in the carbs. There you will need to use some kind of a heat isolating gasket on the carb to intake manifold.

Also in this case, the aluminum intake helps the situation v the iron intake since it cools faster.


The dual 4v fuel log tends to boil the fuel and create vapor lock. If you do regularly drive the car and it does have the original 2x4 intake set up, then consider using a Delrin fuel log. It will not absorb engine heat and will act as a heat insulator.


Camshaft. If you are running a non-original camshaft, you have to get the engine to idle within a certain rpm. One of the reasons Ford used such a mild camshaft on the 67 GT500 was to control the heat issue. Aftermarket cams in hot climates are not going to be able to help you out much.

Timing. You have to find an initial advance to set the distributor at for idle. This is involved with what camshaft you are using. More initial advance at idle is going to help run cooler but you need to keep the rpm's at idle as low as you can get them.

This also means that the advance curve in the distributor compliments the mentioned components.


IF you have strayed from the original 1967 GT500 components, then you have raised the operating temps of the engine.

That all was originally tested by Cantwell pre-production in the Arizona Desert. The overheating issue was delt with and how the engine was offered from the factory was the solution.


You may be in a unique situation and you may need to add a special thicker core radiator that is not off the shelf? Even so, that will not eliminate the fuel peculation issue in the BB in the summer heat.

It would be a good idea to add a large capacity oil cooler as well?


Good luck. You are wrestling with a genuine heat monster and threading the needle to solve it.

[rhjanes]

Great advice above. 
My 428 did this also.  My timing was off.  The running on you describe is a hint towards that.  You might need to have the distributor reworked if you are confident and triple checked the timing.
I also had to learn on big blocks (428), how they like their coolant in the radiator.  on our 302 Mustang, I can fill the radiator to within about an inch of the top of the place where the radiator cap forms the seal.  Look inside the radiator and you will see the lip.   That worked fine for the 302.  So that would be the top tank filled to halfway when cold.  I tried to do that with the 428 and it would dump out coolant.  I'd refill it.  It would dump it.   Once I got the timing correct, it would still dump coolant.  I discussed with a long time Ford man who had built the motor and he said let it dump it.   Then let it cool.  The next day, check the fluid and call him with the results.  The coolant then was about half an inch over the top of the down tubes within the radiator.  I called him and he said "perfect....that's where about all the 390's on up will have the coolant".   I also learned to ignore the electrical in-dash temperature gauge here in Texas.  It will be just a needle width under halfway when fully warmed and driving down the freeway at 65 MPH.  When I stop at a light, it will start creeping up until it is at the 3/4 mark on the way to HOT.  It never reaches the full HOT side.  But you can really feel the heat under that hood, on that firewall, in the garage when I park it. 

[Bob Gaines]

If it is a fresh rebuilt engine at standard bore it could be that it was built with tight clearances causing friction heat. I would also consider blocking off the heat risers in the intake .This will not effect engine cooling but will help prevent heat from the intake boiling the gas in the carbs. That extra heat right under the carb can be a big problem in hot climates. The blocked heat rise might be a issue in Minnesota on cold mornings below freezing but doubt you will see any ill effects in Greece. Also on a street driven car in the hot I ran a fuel log without the tabs that bolt to the intake . Those tabs soak up and transfer heat from the engine to the metal tube and can contribute to boiling gas. Without the tabs the rubber fuel line and steel fuel line hold the log fine. 

[shelbydoug]

It has also been suggested that FE blocks bored 30 or more have the tendency of running hot.

[Road Reptile]

Hi Jakob,
Several things should be checked-coolant type and strenght? 50% antifreeze 50% distilled
water as a starting point. Also the radiator should be tested for good flow. Was it cleaned before the engine rebuild? Also pressure test the cap.An improper thermostat may
limit coolant flow,and with this engine every ounce counts. Ignition timing needs to be checked-engine run on with the key off is not good and timing and idle speed both need to be properly set. Do your basics before spending more money. Let us know what you find
R.R.

[nwfire]

Had a similar issue with #906 a few years ago during a streak of hot weather here in the great Pacific Northwest and had to have a new core in the radiator and also had Flo-Kooler replace the impeller in the water pump with one that flowed more water than the original.  Seemed to solve the problem.

[Jakobs67gt500]

Thank you VERY much for all your kind/professional guidance - greatly appreciated.
We will work through the proposed options, and I will keep you posted on the development.
Best regards
Jakob

[Kent]

I think it's a timing issue and also some wrong parts arround it. Hard to sort it out perfectly but I would definitely start with the timing and maybe change the coolant for a mixture of normal water and some liters of MoCool from Motul as you dont have winter that should work very good.

p.s I wrote you a Personal Message also

[shelbydoug]

I had a "radiator guy" tell me that often on old radiators, he can't get them "boiled out" correctly.

There he would recommend a "recore".


I know that the current crop of "tankless hot water heaters" (for the home) strongly suggest that the core be cleaned out annually with vinegar.

It seems that the vinegar has a positive reaction to the core materials? I assume that mainly being copper?

I don't know what chemicals are in the tank at the radiator shop to "boil them out"? Could it just be a tank of vinegar?

[JWH]

Jakob, is there a fan shroud installed on the radiator?

[Jakobs67gt500]

Jakob, is there a fan shroud installed on the radiator?

Hi there - yes