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I have a question about the running temp. of my 289 in my '65 Mustang. I had it out last week in a warm spell, 85 degrees for the first time and the temp gauge ran about 1/8" below the hot mark. It never went higher and dropped when the car idled. It rises during high speed cruising and even more so if I race and rev the engine for fast acceleration. But upon slow cruising or idling it cools down to about the thermostat temp.

I rebuilt my 289 last year after the oil pump shaft seized and all the bearings failed but did a performance rebuild with 300-350HP (.030 over). The car has factory air but although I rebuilt it I have not had it charged yet. Therefore the radiator is a 3 row type that was replaced 12 years ago but has few miles and I had it flushed and flow and pressure tested. The cap is new. The water pump and thermostat/housing were not replaced but these parts were installed less than a year before the engine failed. The thermostat is a 190 deg type.

The coolant is 60/40 Dexcool with Water Wetter and I replaced the temp sending unit and the instrument regulator. There is absolutely no loss of coolant and the system holds pressure perfectly. Of course all the hoses, heater core etc. were replaced and the spring is in the lower hose. The timing is 18 deg initial with a performance curve and vacuum advance at 10 deg (new Accel distributor).

Does anyone know what temp. the center and the H of the temp gauge corresponds to? In the winter the gauge stabilized at about half way between center and H, so assuming that this is the thermostat temp of 190 deg, I would estimate that the center is 180 deg and the H is around 220 deg. If this is the case then I would still only be running 200-210 deg. Since boiling is around 260 deg. I think this would be acceptable.

However what will happen when I add the air conditioner load? I guess that generating 50% more power than stock might require beefed up cooling capacity. Should I increase flow with an auxiliary electric water pump or go to a 4 row or racing type radiator? I don't think that an electric cooling fan would help since at speed there is plenty of air flow and it actually cools down when stopped so I don't think air flow is the issue. Or should I not worry at all?

Thanks for any help.

Steve D
 
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If you are not worried about original equipment, I suggest an aftermarket aluminum radiator. I have a HOWE radiator in my 68 with factory air. Even in the 100 degree summer heat, the car stayed below 200 degrees while in traffic with the air on. I am using an electric fan with a thermostatic switch that cuts the fan on at about 180 degrees.

Jeff Crumpley
Austin, Texas
68 302 j-code coupe
99 5.0 Eddie Bauer Explorer
 
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My '66 tended to run hot but just the opposite of yours: it heated up when at idle, like at a stoplight but cooled down when running free. The needle crept up to near the H at idle. Let me ask you what may seem like a dumb question: do you have a fan shroud? My PO had for some reason took mine off and I didn't know I was supposed to have one until I started checking out why I was getting hot. I put one on, changed to a flex fan and a 4 row radiator and now it runs cool. BTW, I also have factory air.
 

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take the cap off when the car is cool. start it up and let it get up to temperature. put a thermometer in the radiator. A stable temperature typically indicate everything is running normal. Personally i would not run a 190 degree thermostat except in ohio during the winter.


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It wouldn't be a bad idea to run a real temperature gauge, preferably mechanical, even temporarily. An A/C will cause the temperature to rise (if like in a 69) as the evaporator sits directly in front of the radiator, this will restrict air-flow to the radiator big time. While running the A/C causes more problems as the evaporator itself get pretty hot so the air drawn in to the radiator will be at a slightly higher temp. than when it is not on, then the added load on the engine will also cause some more heat. All our cars, engine builds and accessories are pretty difficult but you could face some cooling problems with you set up when the A/C is up and running. I'd get areal temperature gauge to no for sure when it is all there then start looking at solutions. If you are cooling fine while moving then your radiator has sufficient capacity to the task, if it heats up at standstill the problem is with the fan/shroud combo. If you have that I really am a firm believer in electric fans (especially replacing the direct drive fan) but you may be able to solve the problem with an electric that pushes from the front as a helper.
How hot is a problem is another issue. Some engine will run fine around 220 (check out the thermostat settings for electric fans on newer cars, many 200+). I get a little fidgity if I see 200, but that is me. My set up a rarely get up to 195.

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The only other thing I would add is that you may be running a little lean. This would account for the highspeed/revving making it hot. You might adjust to a little richer mixture and note whether or not this impacts the temp.

Good luck!

Doug-"Whether you think you can or think you cannot.....you're right!!" INDY-USA. GT/CS w/289-2v,PDB,A/C,PS,candyapple red,black top and interior,pertronix,chromeSS Wheels w/ GT centers, 215x14 BFG radial T/A's 3.55:1 open and KYB's
 

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"Does anyone know what temp. the center and the H of the temp gauge corresponds to? "

It doesn't. The readings are a cross between the output resistance of the temperature sending unit and the output of the constant voltage regulator, which is adjustable. The temperature and oil pressure gauges are not calibrated, and are to be used as "indicator" gauges to tell you when things go awry from normal conditions.

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Yes I have the factory fan shroud and the 5 blade fan.

Thanks

Steve D
 

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read my answer to the post previous to yours on how to get actual temperature at one point which would be good at idle and if you have a 190 deg thermostat that would define that point
 
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