I think the ethanol in our gas causes it to run slightly lean. 10%?

Thanks for all the responses.  I am not sure if the gauge reads correctly but I suspect its pretty accurate as the car overheats when the gauge is at the maximum.

As for the car running lean, I am not sure.  I have had it serviced several times at a local Corvette specialty shop.  I have had the carburetor rebuilt, the valves adjusted, and have replaced plugs and wires.  I have to assume that they have checked everything out engine wise as the car has never run better in the 15 years I have owned it.

At this point I think I will wait until spring and replace the radiator. 

Thanks again for all the feed back.

I would make sure the gauge and sending unit are working correctly

My '75 Stingray 350/330 cruises at 190° F on a cool day and approximately 205° F on a hot day. 

I have a 190° F thermostat. If I run the air-conditioning on a hot day, my temp gauge indicates approximately 210° but not in the red, it doesn't seem to affect the engine performance. 

Personally, I think either the cars cooling capacity is either a poor design, or the temperature gauge may not be accurate as designed.

From what I've read in past C3 forums on the internet, this is a common issue. You might take a laser temp sensor and check your engine & radiators under the hood temp, then observe the cars temperature gauge to see if they are close.

You might have to add an external electric cooling fan to help, run 50/50 antifreeze, and of a 180° thermostat if needed.

Hope this is helpful!

I have read that besides the fuel-air ratio, timing and advance can affect engine operating temperature.

1973 L-82 4 spd

My LT-1 is timed to 16 degrees btdc and I am using manifold vacuum with a B28 vacuum advance can.

I run 12° static advance. I forget how much that vacuum advance adds to that but that's mainly at idle and slightly above. I have light springs and heavy weights on mechanical so that advance is all in by around 1800 RPM.  No AIR or EGR. 

That may all change when I get the engine put back in the car because I went from 9.0 compression ratio to 10.0 CR and a slightly more aggressive roller cam .  But I intend to run alcohol-free gas and you can only get that in mid-range and premium around here.

1973 L-82 4 spd

Thanks 73 Shark and F4Gary

I appreciate the info.  To be honest its over my pay grade but io will share the ideas with the shop I go to.

Jim

UPDATE!  Thanks again for all who posted ideas and suggestions.  I did end up replacing the original radiator with a DeWitts Direct Fit aluminum radiator.  It was past 52009 from Top Flight Aoto and it fit perfectly.  I replaced the hoses and shroud foam with part number 39859.  The net result is that the car runs perfectly with the needle indicating a steady 180 degrees.  My only regret is not having done this 2 years ago.  Thanks again to everyone that offered advise and assistance. 

Thanks for the update! Glad you got it resolved!

-Adam Wartell
NCM Lifetime Member #1222
Founder: C3 Vette Registry 
C4 Vette Registry, C6 Vette Registry

My first Vette, now owned by JB79:

 On my '72 350 base with A/C, I had the original tanks fitted with four row tanks 22 years ago. Stock fan and clutch.  The temp gauge bareley goes past the first line, just past it in traffic... I live in Los Angeles...

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