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mikes67
08-14-2011, 08:06 AM
I need some help.
I have a 67 chevelle 300 2 door sedan with a air conditioned 396 that i am have some over heating problems with.

It all started after i had my carb and dist overhauled, it started running a little warmer that normal so i dropped the thermostat to a 180 and put a fan blade extension in to move the fan closer to the radiator helped a little.

I thought if i put a aluminum radiator in that would solve some of the problem and look good did not work tem actually went up from 180 to 190/210 idle would come down when moving, dropped a 165 thermostat in temp went to 185/190 idel sometimes it would creep up to 210 if i had to sit longer or turn the ac on it would really run up. I bought a pair od 12" fans and shroud and things really went wrong the temp went to 210/220 idel and 220/230 crusing no ac take fans off it runs 220/230 crusing scary with aluminum heads.

This is a three row aluminum radiator, i have bought new spal fans waiting to install if i can figure out why the radiator won't even cool without fans on. I went bach to stock fan and shroud and it runs 220/230

help

earthquake68
08-25-2011, 11:41 AM
What a lot of people overlook is fuel and timing. You said right after carb and timing work, it started to heat up. What exactly did you do? If the timing is too far advanced it will cause heat and if your engine is running too lean, it can create A LOT of heat. Fuel as a liquid helps cool the heads down. Check these two things and see what you find.

Ms Grumpy
08-25-2011, 03:55 PM
Alan, I am one of these "a lot of people" who had overlooked the fuel and timing as a cause for heat build up. Thanks for bringing it back to the fore front.

70SS454
08-23-2012, 10:01 AM
I have the same problem with my 454. All stock original motor. My norm is 210 degrees and heats up to 230-235 at light. New therm, fan clutch, hoses.mstill same

Ms Grumpy
08-23-2012, 06:22 PM
Just a quick question here. What is the "best/correct" temperature for a motor to run. The reason that I am asking is that I had an temperature problem on my way down to the Ohio show a few weeks back. In talking to many knowledgeable people I was told that it is not unusual for a motor to run 230, and in some instances it is almost better for the motor to run at a higher temperature.

So which is it ? Is a low temp (and what is that low temp) better for the motor, or is a higher temp (and how high really should it go) better for the motor.

Hank70SS
09-01-2012, 05:14 PM
Just a quick question here. What is the "best/correct" temperature for a motor to run. The reason that I am asking is that I had an temperature problem on my way down to the Ohio show a few weeks back. In talking to many knowledgeable people I was told that it is not unusual for a motor to run 230, and in some instances it is almost better for the motor to run at a higher temperature.

So which is it ? Is a low temp (and what is that low temp) better for the motor, or is a higher temp (and how high really should it go) better for the motor.

All 70 Chevelle engines except the 396 (402) came from the factory with a 195* thermostat. Don't know why but the 396 came with a 180* thermostat. It is a big debate, hotter engine burns fuel more efficiently and produces more power. Not an over heated engine but one that is fully warmed up including the oil. Cooler engine, less stress on the oil and parts. Dyno oil doesn't start to break down below 250*, syn oils can withstand even higher temps. Since oil temps can run 10-20 degrees higher than water temp you want engine temp below at least 230 to protect the oil. Of course you don't want to run at 230 all the time or even 225. But 200 even 210 at times is nothing to worry about.

If you have a 180* thermostat and run 200 or above your cooling system may be a little weak but you're not running in the danger zone. These 40 year old cars didn't have the air dams, etc like newer cars that keep engine temps more consistent. Most newer cars run a coolant temp in the 190-200 range. They seldom go above that because of the improved design of the cooling system and air flow.

Ms Grumpy
09-02-2012, 09:14 PM
Great explanation. Thanks Hank.