# Operating Temp



## devildawg (Apr 27, 2012)

Greetings everyone. Ive been following the various threads on running hot over the last 14 months with great interest and hope that my experience may help those having similar problems. I have a 65 Tempest sports coupe 326 bored .030 over with a mild melling cam that was running at 200 cruising and climb to 220 stuck in traffic regardless of the air temp.The timing and all other obvious potentials have been checked and the engine was running like that since the rebuild and correct cam break in procedure. Ive been making adjustments over the last year one at a time to see what would ultimately drop the temp to a more comforting level. It now has the 65 Tempest chassis manual recommended 180 thermostat. My research from the chassis manual states that the temp light comes on at 248.I finally found the normal operating temp in the 65 Tempest reliability assurance inspectors guide page 41 under the hot idle speed adjustment and it says adjust at normal operating temp 177 to 182. This manual covers all Tempest,Lemans and GTO motors. One more interesting note is found in the 65 owners guide and says normal operating temp should be 180 or above . If gauge reads 245 take immediate action to find the cause. The following are the items I changed or added with little or no effect 1) high flow 180 thermostat 2) high flow water pump/ flow cooler. 3) divider plate adjusted from 1/4 inch to 1/16. 4) a four core brass copper desert radiator. 5) added a fan shroud. 6) changed from a four blade to a clutched 7 blade.8) a dual electric fan set up pushing with a thermostat set to come on at 200. This kept it from going over 212 stuck in traffic and did help with the peak temp lowering it 8 degrees 9) out of desperation added water wetter. And finally what worked ?? I installed a U.S. radiator aluminum desert cooler radiator that appears stock. Now she runs down the road at 180 and never went over 200 stuck in traffic with outside temp at 95 (HALLELUJAH).I tried to keep it simple but wanted to share my experience and highly suggest after first checking the common culprits as already discussed in previous threads that trying an aluminum radiator first may save a lot of time and money. Ive posted a few slide shows of my restoration on youTube titled 65 Tempest Restoration for those interested. 
Happy motoring to you all


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## ibarbuckle (Feb 24, 2014)

Interesting. Thanks for posting. Did you look into your ignition timing before doing all of the above?


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## geeteeohguy (Feb 2, 2008)

My '67 convertible has been running over 200 degrees for the past 248,000 miles with no ill affects. It has no gauge, just a light. Running at 220 or less is perfectly fine. Running 180-195 is ideal, though, with today's bad gas. Less likely to detonate. Glad you got it down to where you're comfortable. My '65 hardtop was running 200-plus for many years, until I installed the correct temp. sensor from Lectric Limited. Turns out the acutal temp was/is about 185! So, first off, check the actual temp of the engine with a pyrometer and verify the REAL temperature it's running at.


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