Regarding thermostats, cooling etc........
I went through temp issues with my FE a few years ago.
Here's what I found in trying to keep my FE cool:
- The best coolant for cars is distilled water, however, straight water does not have the lubrication/protection properties of anti-freeze (tap water has minerals which can calcify and react which engine part such as aluminum) so I use a mixture of 25% anti-freeze 75% distilled water (this should work for most folks unless you drive your Cobra in the freezing cold....I'm in CA
)
- I saw no noticeable reduction in temps using "water-wetter"
- Edelbrock waterpump with it's CNC design really does work and reduced running temps by 8-10deg. The CNC machining provides a balanced flow to the heads and closer impeller to housing clearance. This reduces cavatation which induces air in the system. (air makes steam which does not cool anything)
- The addition of pusher fans reduces temps by about 5deg
- Anti-freeze is NOT a coolant, what it does is reduces the freeze point and raises the boiling point of water and does NOTHING to keep your engine cooler
- Fan shrouds provide 8-10deg of cooling
- The rating of a thermostat is the temp at which it it designed to open and maintain a MINIMUM operating temp. In WARMER climates a lower value 160deg. may be desired since this can help keep the temps lower by allowing a lower minimum operating temp. when there is sufficient airflow thru the radiator. The 160deg. provides a greater delta (difference) between minimum to a maximum temp. From "Minimum" temp on a 160deg. a 40deg rise is 200deg, a 40deg rise on a 180deg is 220deg
- So my FE was running at 190-210 before I added the above mentioned coolant, Edelbrock WP, shroud, pusher fans and 160 T-stat. My average temp regardless of whether it's hot or cold outside is now about 170 on the highway. There is no one thing that is going to make an FE run cooler it's a combination of components working together.
As for the "steam hole". The hole is actually a by-pass which allows additional coolant flow. This can help with cooling as long as the hole is not to big however, restrictions in the cooling system are necessary. With to much flow in the cooling system (which can be the issue with restrictor plates) , the coolant does not have sufficient time to transfer heat via the radiator and the engine will run hotter.
hope this help some,
Mike