# water temp - 66 gto



## Chris-Austria (Dec 23, 2010)

Hi!

I'm wondering if my cooling system is working good enough.
It's a 66 GTO with a 428cui engine and 4 speed manual. Ignition is set to 10° (instead of 6° because I'm using headers).
I have a 3" aluminum radiator and a flex a lite electric fan (1x15"), a 180° thermostat and the original water pump. 

While driving the temp goes to 185-190°, on the highway the temp goes to about 200 if I drive faster (70-80 mph).
But in slow traffic through town the temp is always at about 210° and won't go down even with my fan. 

I'm afraid if the outside temperatures are getting warmer, my cooling may not be efficient enough. What do you think and do you have any ideas for improvement?

I'd like the temp to stay always between 180-200° even in summer (outside temps about 90°).

Chris


----------



## geeteeohguy (Feb 2, 2008)

If your temp raises in traffic but goes down on the hiway, you're not pulling enough air through the radiator core to dissipate the heat. You need a better fan. I'm using a 19.5 inch 7 blade mechanical GM fan with clutch and shroud on the '65 and an 18" 7 blade GM flex fan with shroud on the '67 without issue. 210 degrees is not, however, overheating. Over 230 is. Did you clearance your water pump impellor?


----------



## Chris-Austria (Dec 23, 2010)

Do you think an mechanical fan will be better than an electic one? 
What is "clearance" the water pump impeller? The water pump is still driven by a belt (no electical water pump).


----------



## lewy222 (Apr 17, 2011)

Chris-Austria said:


> Do you think an mechanical fan will be better than an electic one?
> What is "clearance" the water pump impeller? The water pump is still driven by a belt (no electical water pump).


To clearance a water pump, take the pump and the divider plate off of the motor. You'll need new pump gaskets, set the pump face down (so the impeller is facing up) and put the gasket, then the divider plate over the pump and check the clearence between the impeller and plate at the center hole. It should be pretty tight. If it isnt, lightly bend the plate so that you are .025 or closer. 

As far as the electric fan, I've never run one. I plan on using a good quality aluminum radiator, a high flow 160 degree thermostat and a stock fan on my 68.


----------



## lewy222 (Apr 17, 2011)

I should add, the .025 is arbitrary. I dont know that number to be based on anything, the goal is to go as close as you can without touching the impeller or without warping or otherwise ruining the divider plate.


----------

