heating/cooling??

[raj4851]

I have a '39 Ford with a 355SBC, Mustang radiator, flex fan, and an auxilary electric fan with an adjustable thermostat. When running a 180 stat, it ran about 160 going down the road. I changed to a 195 and it did fine (190) until I parked it and let it idle. It got to about 210 which didn't bother me a lot but when I shut it off it went to 230. I turned on the electric fan and it cooled down pretty quick. I don't have a shroud but have an aluminum one I plan to install. I'm running a tunnel ram with two AFBs so right now I'm not running a hood top panel(it's a standard model). I really don't want to wire the fan so it runs when the engine is off. I have an overflow tank but it is not at the top of the rediator. I'll change that too. Any ideas? Thanks in advance, Rod

[rspears]

Rod, I would suggest that you get the shroud installed and then take the electric fan off to give you free air flow through the radiator. A pusher fan out front is going to block air flow and with a shroud you won't need it. Having the temp go up when you shut down is normal, as you've stopped coolant flow, and all of the residual heat in the block is going into the coolant in the block. If you start the engine when it's reading 230F you'll see the temp fall very quickly as you re-mix the coolant in the block & radiator.

[Scooting]

As Roger said, put the shroud on. Air flow is very important. Do you have a plate over the grille at the hood latch to keep air from going over the radiator? That makes a big difference. Also look at air exit if you elect to put the hood back on. The air should have a large area by the back of the front wheels to exit. If you have headers and they seem to contribute a lot of heat, wrap them. Your temps are not bad, use the 195 or 190 thermostat not the 160. If it warms while sitting, as long as it does not overflow and will restart, as Roger said, it will cool right down.

[R Pope]

Get rid of the flex fan, too. They don't move as much air as the factory ones, and they are baloney slicers, dangerous, especially without a hood.

[raj4851]

Hi guys, and thanks for all the info. I moved my overflow tank up a point even with the top of the radiator. Also, the hose on the bottom of the tank wasn't tight enough. Now it runs at 190 all the time and goes to about 205-210 when I shut it off. There is no puking of coolant. Again, thanks for all the advise and I'll be watching to see if I need to make the additional changes you all have mentioned. Thanks very much, Rod

[chopt50wgn]

I just wanted to add something here ..............when your sensor for the temp gauge is located at the front of the manifold near the top hose outlet.............what you see on the gauge is the temp of the coolant at it's hottest point and if the fan,pump and rad are doing their jobs, the coolant temp in the block can be 20-30 degrees cooler than what the gauge is telling you. Also the coolant temps that are passing the sensor are also coolant that's leaving the motor. The gauge is not registering what temps are in the motor, only telling you how hot the coolant is leaving.

[lurker mick]

raj4851, educate me on how moving the overflow tank up and a tighter hose to the overflow is making a 20 degree difference in temp?

I'm not doubting you, just trying to learn.

Mick

[MelloYello]

I also have a question. Did you install the shroud?

[raj4851]

Hi guys. chopt, thanks for the info. I wasn't sure about the temp reading. It's good to know that the block is not that hot. Thanks again.
lurker, I moved the overflow tank about even with the top tank to keep the water levels equal. That way, it's less likely to puke out. Also, and maybe most importantly, the overflow hose going to the bottom of the overflow tank was loose, causing coolant to "spew" a little, losing coolant so the temp went up.
Mello, no, I haven't put the shroud on yet. I drove it today and in stop & go traffic in town it creeped up to about 195 but went right back down to 190 as soon as I started to move. Yes, I will get the shroud mounted pretty quick. Thanks again to all.