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Old 05-09-2012, 05:51 PM
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Default Chevelle running hot

I have not had my 70 chevelle long. This is the first warm weather I have driven it in. Today my 454 really started running hot while sitting at the light. It usually runs around 200-220 degrees. It was headed over 240 on its way up. It's a Texas car now and was in Wyoming most of its life. It dumps the antifreeze overboard when it warms. There is no resivoir on it. Should there be one? Do I need a differrent thermostat? I think it would have given me a temp light if I had to is t much longer.
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Old 05-09-2012, 07:17 PM
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You said you haven't had it long. Did you change all the fluids ? I know that it can get pretty hot in Texas, a new thermostat would be a cheap way to try to solve the problem, but maybe a new radiator might be in the cards.
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Old 05-09-2012, 08:05 PM
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Tell us more...
What does your car have for a fan? Does it have a shroud? What is the initial & total timing set at? How many rows are in the radiator core?
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Old 05-09-2012, 08:27 PM
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As Bill said there is a lot at play here, we need to more. Retarded timing will cause it to run hotter. No shroud on the rad will cause it to run hotter. Tell us your setup and maybe we can help.
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Old 05-11-2012, 07:14 PM
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I do have a fan shroud. The car was a Wyoming car it whole life until a few months ago. I have changed fluids but not the cooling fluids. It looks pretty clean and I have added several times because it dumps it over when it warms up. The car is pretty original. It belonged to my father-in-law who liked for things stay stock. I believe the timing is where it should be, not advanced and I think the radiator is fairly stock. The car runs beautifully. I guess I should start with the thermostat. Then move to installing an over flow tank like I did on my old jeep cj7 when I restored it. I really don't know much about this car yet.
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Old 05-11-2012, 07:32 PM
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Let us know how things work out. Good Luck.
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Old 05-11-2012, 08:09 PM
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Do you guys run a overflow resivoir on your big blocks?
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Old 05-12-2012, 07:44 AM
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You don't fill the rad to the top on these cars. About 4" to 5" below the top. You can add an overflow tank but it's not necessary, I don't have one and mine never overflows. If it's the original rad it could be plugged up. Maybe just a flush or maybe it will need a recore.

If your timing is set to stock specs it probably needs to be advanced some. Chevy big blocks love a lot of timing advance. Try setting it to 16* even 18* at idle. Watch for spark knock, it can kill an engine. You may want to start at 14*, if no knock, try 16* then 18*. You'll need a dial back timing light or timing tape around the damper to check total mechanical advance timing. It should be around 35*, 36* and should be all in between 3,000 to 3,500 rpm. Your mechanical advance may not be working well if it's a stock distributor and not been rebuilt in awhile. The above timing checks are done with vacuum advance disconnected and plugged. If you're sitting at stock timing now that 454 will really wake up with more timing advance.

You have a fan shroud, is it a stock clutch fan setup? Fan blades should be about half way into the shroud. Is the clutch good? May be time to replace it.

Check vacuum hoses, make sure they're all good with no cracks. A vacuum leak can cause it to run lean and that will make it run hot.
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Old 05-12-2012, 10:43 PM
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Thanks hank, I'll check that this week and get back to you. I know the distributor has been updated but can't remember to what. I'll check.
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Old 05-13-2012, 08:29 AM
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On a non AC car the fan shroud only covers some of the radiator leaving part of the radiator with no air flow. On a friends car we put a AC fan shroud on it so when he is at idle it no longer over heats. The shroud cover the entire radiator and you still retain a stock look.

Also Hank great info.
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