[Formulabruce]

Hope you dont have an automatic. use and IR gun on the T stat housing.
your gauge is probably wrong.
There should be at least 10 lbs pressure when hot.

[80shaker]

Originally Posted by Formulabruce

Hope you dont have an automatic. use and IR gun on the T stat housing.
your gauge is probably wrong.
There should be at least 10 lbs pressure when hot.

Was that in response to my post? I checked again today, and there is pressure in there and coolant in the surge tank. I put one of those mr gasket rad caps on today and ran the car up to 220 (cluster gauge) until the fans kicked on (efans) and the cap thermometer said 160 degrees. I don't know how accurate that is but maybe I should run in around town for a bit before drawing any conclusions? I have an external tranny cooler, so my radiators trans cooler isn't being utilized. Does drilling a small hole in the t-stat actually help? I've heard of a couple people doing that and claiming it put them back in the correct temp range. btw my t-stat is a 170 degree for a 461 stroker, 6x heads.

[Formulabruce]

Check IR on the T stat housing.
What is your fan switch at? should be turning on no later than 180 ( napa has lots of choices, I spent many years fixing 3rd gens this way)
need to keep that tranny under 200 for sure.
You could easily run a 160 T stat as well, keep in mind that 160 is "static", it starts to open at 160, its not FULL open till 170-175. ( dynamic)
once full open the heat exchanger(radiator) and capacity determine your temp with circulation.
Your set up( 9.5 to 1?) with a clutch fan and a 4 core on a 80 degree day should be able to sit at 182-187 idling. youll still be over 200 in the combustion chamber, for efficiency.
hope that helps

[Pontirag]

thats hard to say if the guage is working correctly. different set of tests. but the fact that your system is holding a vacuum means that there are no leaks in the system.

alot of people are responding to you inquirey as though your system is under pressure. I have reread your intitial post and it referes to two issues the "release of pressure of the system when the radiator cap is removed after a few days

and

temp ranges, according to the guage of 220 plus degrees

in agood cooling system after it has run up to temp and then been allowed to sit and cool off for a few days, when you remove the cap that release of air noise is actualy air rushing into th system and not escaping. its an indication that the system has no leaks to the outside atmospheric pressure.

[FrankieT/A]

If you're gonna run a recovery tank you will need to use a late model cap. Because: the early caps when cars had no recovery system used one gasket at the bottom of the relief valve. In the old days the fluid got hot, expanded and belched out coolant and it went to the atmosphere. However, in a recovery system the cap has two gaskets,one at the original location plus at the top (at the mouth of the radiator) 'cause as the coolant cools it creates a vacuum (due to contraction) thusly drawing coolant from the tank. (the hose from the radiator must enter the tank from the bottom or have a straw type hose if you will from the cap because obviously the hose must be submerged in coolant to create the syphon back to the rad). Lev-R-Vent type caps do not work on coolant recovery systems. Anyone who has canned meat or vegetables knows you put the product in the jar "Hot", when it cools and you open the lid you hear the air rush in. As the jar cools, the stuff inside contracts and creates the low pressure. Voila! Vacuum packed.

Hope this helps!