Preferred 727 Operating Temperature?

[73LemonTwist]

I have been cruising through the various threads regarding auxiliary transmission coolers. The question I have is what return temperature to target? Is the objective to get the return temperature as low as possible, or is there a preferred operating range?

I checked the shop manual and it does not provide any information regarding transmission fluid temperature operating range.

My '73 340 RR came with the Max Cooling package installed, so it has the 28" rad. On a 75 degree day, at 70 mph, my trans fluid temp exiting the cooler in the rad runs 120-130 Deg F.

Is there any need or advantage to cooling the return fluid temperature below 120?

I have not measured the fluid temp leaving the trans heading to the cooler (yet). What is the upper end of that temperature that one should target for normal operation?

Thanks folks...

 

[Photon440]

Normal is usually considered around 175 - 200. Problems start over 230.

 

[66Satellite47]

I've always considered 160 - 180 to be real good. Much over 200 -210 gets dicey. My opinion.

 

[pnora]

You have to wonder how can a cooler work to cool less than radiator temperature. Figure the lower tank cooler is immersed in coolant at 160 to 200 degrees. You would have to think in order for it to lower the temperature less than the coolant you would have to have a oil to air cooler.

 

[Charged440]

I used a temp gun to check this out and I don't remember what the exact temps were but the bottom of the radiator was much cooler than you might expect. Something like 175 at the top and 100 at the bottom with the trans cooler input line being somewhere in between. I remember reading some time ago that a slipping transmission could actually heat up the radiator.

 

[66Satellite47]

I should have said my temp suggestion was based on an aftermarket convertor 10" Turbo Action used for both strip & street.
Similar for drag race 727 with 8" convertors.