A mention of a thermo fan in another thread and the prospect of doing a car rally on a 30deg day I thought I would start a thread about keeping these things cool.  I have had a thermo fan but it just loaded the electrical system up which in turn made the engine work harder at idle so it didn't seem to achieve anything. 
 
I had a mate who fitted a metal flexi fan and nearly cut his finger off on it when adjusting the timing, I have seen modified cowlings to try and trap more air and have seen holes drilled in the beaver panel to let more air in to the bottom half of the radiator.  I have fitted a 3 core custom radiator with a recovery system to one of mine but haven't stress tested it yet. 
 
I have also seen a good article in the UK club mag based on a Perth car that had its whole cooling system re done but I cant find it.
 
It would be nice to be able to sit in traffic without stressing over how quickly that needle is heading to the red.
 
It would also be nice to know where in the range the needle should sit.  One of mine sits at 1/4 the other at 1/2 way.

I've got an electric fan - an old one that came with the car. Works fine (only draws about 10A) which wouldn't load the engine. Have adjustable thermal switch - temperature gauge sits about a third. The only problem I've had with over heating was suspect thermostat.

Can't speak for the V6 just what I know from the other same era cars I've owned.
The only problems I've had has come down to poorly maintained cooling systems, blocked radiators, worn pumps and thermostats.
Tune will play a part, correct timing, dwell and mixture settings will help no end.
Cowl's do an important job, alot of people seem to think removing them will increase flow, I know I did in my earlier years and don't seem to be the only one, the cowl was one of the hardest parts to find when rebuilding the RS.
I'll tolerate a bit of temperature creep, its part of the experience and charm of driving old cars for me. I've had the Cortina hit 3/4 temp stuck in traffic on a 37 degree Perth day, I just turned down the next side street and modified my route to keep the air flowing. Its always an adventure driving an older car.
Cheers Drew

The specialty coating applied to the extractors claims to drop engine bay temp by about 30%, its not huge money.  Ensure that a thermostat is fitted as the Essex seems to cavitate without one.  Also "burp" the cooling system when refilling, you must wait for the thermostat to open and top up.   

The advantages of a thermo fan over a fixed fan are well proven.
One problem i had was that, after installing a recovery system i noticed that the radiator  always developed an air gap under the cap. This was caused by a heater core that was leaking, when this was fixed there were no more temp fluctuations. This left the thermo fan to do the job it was designed for.

No doubt about thermo fans for power economy etc at speed, but my result many years ago on a 40 deg day in a traffic jam was not so positive, so I am like Drew always looking for a way that will keep me on the move even if it takes longer.  I will keep searching for that article, it was all about a cooling system modification that made a big improvement.  I'm also thinking about a calibrated temp gauge in the console instead of the clock.

As proved in my 1972 GTV6, a properly maintained cooling system in any car that's tuned properly and has no other related faults, will not overheat.  Ever since owning my Capri 5 years ago, I have run it with NO fan at all and it still runs cool (half meter deflection), on 35 degree days as long as I'm moving and not in peak hour grid lock.  Given that I would not recommend everyone repeat my deletion of the fan, which Ive done for added power, I should add that the previous owner assured me that when the welch plugs and head gaskets had to be replaced some decades ago, the block and heads were steam cleaned after a hot bath cleanout by the local engine reconditioner(this ensures removal of all crud build up that helps cause overheating). Brass welch plugs were then fitted. Modern anti-feeze/anti boil at a ratio of 1:1 with clean water ever since, along with a German Wahler (the best money can buy) Thermostat of 74 degrees (while we're here on thermostats, ensure your new thermostat has a 1 mm hole in its outer flange, and if fitted with a jiggle pin, cut it off;  for full flow and help to "burp" the system and ensure a trickle at all times).  The radiator was professionally rodded-out and hot bathed, back then decades ago, as well.
       I've had untold numbers of customers in my workshop over the years, with overheating in new and old cars, and the common fault is always failure to ensure proper maintenance as outlined above. 
       The answer to "normal needle position" once operating temperature is reached, is "anywhere in the black" (1/4 to 3/4) depending on "load", speed and ambient temperature.   Running below 1/4 can be just as harmful as running too hot; usually caused by a "failed-open" Thermostat. This is rare.
       When chasing problems, always pressure Test System and check every single area where coolant goes. 
The Radiator Cap must be pressure tested and replaced if in doubt.  The thermostat must tested .  The Radiator must be tested.  The engine and all its ancilliaries must be in Tune. 
       Don't pretend doing your tests !  Make sure ALL tests are actually done correctly and results analysed correctly, else you're wasting your time and still overheating.  "A Chain is Only as Strong as its Weakest Link".
If you dont know what you're doing, ask around as to who is a Professional Mechanic, and stay wide of "cowboys" and back-yarders; your wallet and car and sanity depend on it.
.....one more point......Make sure you dont have "brake drag/seizure" at any wheel, as this is just one more log on the fire

////////////      Needless to say, I fully agree with DrewDog looking for long free flowing back roads rather than short grid lock routes !

i live close to the city and all around me is nothing but traffic jamers and people who dont know road lane rules  it sucks big time i installed thermo just in case i need it  my temp stays in the blue to just above it  ......
the capri and i both hate it when you just cant get the car over 40ks due to idiots who hog the right lane doing 40ks in 60 and 70k zones .. we also hate how they have let the developers jam and choke the area's up ..

Did the charity run today in the hot orange, 90 min drive in all sorts of traffic, very nerve racking in a car that I don't know that well but didn't have any problems.  I wasn't alone, the topic of the day for all makes and models at the destination was how long was spent watching the temp gauge.
 
I remembered the problem with my old car with thermo fan.  When the fan kicked in at idle, the volts would drop so I had to push the revs up to get the volts up but that caused more heat and it became a vicious circle trying to keep both temp and volts gauges happy. 
 
Looking at the fan position, grill size and alternator output I am thinking a 10in pusher fan at the bottom right of the radiator just in case I ever get stuck on a really hot day would be a good idea and would also consider converting the fan to viscous coupling.
 
That should sort the engine out now need to look after the passengers.  The wife wants air con now so that extra load on the engine could be a bit of a challenge.