[TR] TR3/TR4 cooling

[Jerry Van Vlack]

Folks,
Lots of interesting information as it relates to cooling and the elimination 
of the engine driven fan. All good information too. I'd like to add to that 
with some personal experirnces. I eliminated the mechanical fan on my 4A and 
saw an improvement in overall vibration that was caused by the mechanical 
fan at higher speeds. I liked that.

There is a down side and it hasn't been discussed. Without an engine driven 
fan there is considerable under hood heat build up at slow speed in traffic 
or of course while stopped at a light or stop and go traffic conjestion. At 
slow speed the engine fan keeps air moving uder the hood where an electric 
fan does not if it doesn't turn on immediately. That lack of air circulation 
resulted in my case to vapor locking. Remember; our carbs sit right above 
the exhaust manifold and heat rises. My system uses a temperature sensor 
installed in the top tank of the radiator and is set to come on at approx 
185. I run a 160 thermostat (original sleeved type which came with my car 
when I bought the car in 1969). It turns off at something below 175 as I 
recall. So if I find myself in heavy traffic I need to remember to manually 
turn the fan on or I'll have bigger problems in a very short time. There is 
a thin line between vapor lock or not and once it occurs the only thing that 
resolves it is getting the car moving at something over 25mph. to get under 
hood air circulation again and cool the fuel.

I added one of Joe Alexander's SS Heat Shields too and that made a 
significant improvement towards keeping the carb float bowls cooler.

So if you experience vapor lock in traffic and have an electric fan 
conversion you may try remembering to manually turn on your fan and install 
a heat shield.

JVV