# I have mostly conquered my 68 400 GTO engine overheating problem!



## MyPopsGTO (Jul 12, 2020)

I promised a few people that I would let them know how I fixed my overheating problem. Over the past 1.5 years, I have replaced a lot of things: new radiator, new electric fans, new high amp alternator (for the electric fans), new water pump, new thermostats (a few actually at different temps), etc. Additionally, I had checked a number of times, ignition timing at idle, air/fuel mixtures screws on my Edelbrock carb, etc. BUT - I never checked my "total timing (advanced)." Wow! For past year, I would run the car for 15 minutes and it would hit 210 degrees. Today was different. I invested in a great Innova timing light, dialed in 34 degrees, and re-timed this hot beast. Ran it for an hour and it danced around the 200 degree line, not the 210 degree line -- which had been a common sight. 
Now I really need the wisdom & experience of this community. I think I can reduce the operating temp a few more degrees with a little more precision on the total timing side. I called the previous owner of the car and found out that during the rebuild of 20 years ago, he installed a CompCam 268 camshaft. He was not sure if it gave him more torque from the line or more HP at the high end of the RPM curve.
Considering that I have this camshaft in my 68 400 engine (.20 bored over), can anyone suggest what I really need to dial into for my total timing so I can reduce operating temp a few more degrees. For me to run a little cooler, in theory, would I need more advance (+34 BTDC) or start to go in the other direction?
I am very grateful so far for everyone's thoughts and ideas so far! I am excited to close the chapter on my engine overheating problem!


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## Lemans guy (Oct 14, 2014)

Read some of the timing threads on the forum, yes you can improve your timing curve and help cooling. Even more so at idle when the engines need the cooling as well..


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## Lemans guy (Oct 14, 2014)

I set them at 36 degrees total timing, 34 is ok. The relationship of base timing to Centrifigal timing and the vac Vance timing all come into smooth powerful running and cooling improvement. Total timing 34 or 36 is just one part of the equation. But very important.


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## Atarchus (Aug 4, 2020)

With a good radiator and electric fans, you really shouldn't have any issue. I have a cold case radiator with their 14" dual electric fan/shroud kit and it has no issues controlling the temps. On the freeway I cruise at 172 degrees (that's when the thermostat opens). Dialing in timing might help, but it sounds like something else is off. How big are your electric fans? Is there a fan shroud? What temp thermostat? What water pump?


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