[Greenchevelle1970]

At 50 degrees outside car runs fine. Runs at about 190 to 200. Had an 80 degree weather day, it ran to 210 215 while cruising and at a stop light went to 220 and then 230 before I got moving then it stayed about 210 until i stopped at my house. The fan when cold and not running you can spin the fan with a little tension but seems to be engaging when I pulled into the garage engine how at it was spinning pretty fast. Is there a possibility that the fan is spinning but not at full speed? radiator is a factory 3 core 165 degree high flow thermastat. I just got this 1970 LS6 4 speed a few months ago and freaked out that I wont be able to drive it in the summer months. Tell me the LS6 can go for a cruise at outside hot days without temp issues. Do I need to do a 4 core radiator and electric fans or can my stock work. Maybe due to timing of running rich? I am also going to put in a overflow tank to have more coolant. the water pump is going and flowing properly. Any thoughts Id appreciate it. thanks you.

 

[Lew540]

A photo to help to see the set up to make sure you have a fan shroud pulley sizes etc. You might just need a new fan clutch but without some photos we don't know what you have. For all we know you could have a 14 inch fan in there when you need an 18 inch fan.

 

[Greenchevelle1970]

car all stock 18in fan seven blade hope this helps

 

[Road Roamer]

I have one of these and it's awesome! Never gets above 180 using a 170 thermostat. Lifetime warranty. DeWitts Radiator 32-1149003M DeWitts HP-Series Radiators | Summit Racing

 

[Darren Trudeau]

It could be the fan clutch or size as been said already.
It could be the initial timing too low or froze mechanical or vacuum adv. pod not working.

Start checking things to eliminate what it isn't and you'll probably find what it is.

I have a 396 that has a bit of a cam in it that was always hot (210-220 and would keep climbing) until I fixed the timing now it's 195 putzing around on a hot day then cools to 185 driving at 40mph.

All chev big blocks benefit even stock from a proper initial and curve setup.

Do a search on here and you'll find more than you can read.
Don't freak out, once you get it dialed it will be great, Guys on here love to help with this stuff...
D

 

[vortec710]

Some time back there was an article on the corvette sites on how to adjust the original style fans, assuming it is still mechanically OK, might be worth your time to look up...FWIW

 

[oldcutlass]

It could be the clutch or your timing is retarded as stated above. Another issue could be too lean of fuel settings.

 

[-SS454-]

It doesn't appear to have AC, but is there anything in front of the radiator blocking air flow?

210-215 while cruising is pretty bad.

Have you checked your radiator fluid levels?
Is the thermostat functioning correctly? Was it installed correctly?
What is your timing?


Off topic but how is the belt alignment. From the pictures they look way off and I think you'll be throwing belts if it isn't corrected.

 

[Greenchevelle1970]

yeah Im gonna do a set up on it check timing and fuel mixure settings this week. Ill check alignment of belts I think the angle of the pic makes it look off but I think they are aligned. fluid level full radiator thermastat ill watch it with a thermal gun to make sure but it seams to be functioning. I had no idea that timing could cause the motor to run hot. also what should be my spark plug gap and what am i looking for on spark plug, no soot right?

 

[Kirk's67SS]

A little Wider Pic // Not so Close & further Away will show us the the Over All look better
And a Pic of what is in Front of the Rad Core // Grill Side

 

[Capt Casey]

Go for the easy things first like thermostat... they don't last forever and sometimes stick.
Try driving with your heater on hot and fan on full and see if this helps lower temp if so yes it's a cooling issue.
Could be air in the hoses and not getting enough coolant through the system.
Clutch fan not working correctly.
rad cap not correct or sealing?

Spark plugs too hot
Trans fluid if Auto too low?

Timing as you said.

Airflow or rad shroud not allowing air through.
back flush radiator or blow compressed air through you rad from the fan/engine side.
Just a few thoughts before re and re ing a new rad.

 

[Lew540]

Clutch fan like the other guy had today with his ls6.

 

[boyd66k20]

772 fan/18", Hayden 2747 clutch, shroud, 1/2 in 1/2 out in the shroud, 160 thermostat, 70 water 30 antifreeze, at least a 3 core radiator, timing set properly, verify temperature gauge works. After all that if it still overheats, go to a newer radiator. 2 row aluminum 1" fins.

 

[Dean]

I too think it's probably a bad fan clutch.

 

[OLDED]

The in dash gauge may be reading wrong also. Add in a new mechanical gauge to confirm the accuracy/inaccuracy of the in dash one. It is better to have the fan blade slightly inside the shroud for best air flow.

 

[Natedawg]

A lean condition can cause overheating as well. Carb tuning and timing make a difference.

 

[Greenchevelle1970]

After using a infared hear gun the car was at 170/175 reading 205/210 on factory gauge at 38ohms, so the car actually isnt over heating but now is it the sender or gauge. Before I rip of the dash pad I'd like to know for sure its not the sender. Also my fuel guage reads 3/4 at full and at straight empty on the line of E its at a half a tank. is that the pickup or the guage and how to figure that out. BTW the 165 thermostat opened at correct time, so glad its not over heating but would like the gauges to read accurately. thanks for all the help and input so far. Drove her to work today huge smile on my face

 

[LeoP]

Senders have a resistance that needs to be known to get the correct unit to use with different vendors gauges. is your gauge factory or aftermarket??

 

[Greenchevelle1970]

Factory Guage probably original.

 

[DUTCH MAX HEADWORK]

If it's an LS6 the timing is probably retarded to get by on the crap gas available now.

Drain some coolant from the rad and look into the radiator cap. Are the tubes clean or cauliflowered?
You probably have an original Harrison radiator and to keep the value of the LS6 it would be best to hang onto it and have it rodded out if you suspect any flow issues through the radiator. It looks pretty clean on the outside. If you decide to go with another radiator, box up the original and hang on to it.

My first thought is that it's probably the fan clutch. When cold, it should barely be able to be turned by hand. When hot it should be fairly hard to turn also. You should be able to hear the fan kicking on and off if you listen for it. The HD Hayden 2747 clutch is about 50 bucks. If that's an original fan clutch, box it up and hang on to it. It can be rebuilt.

Run a 180 StantSuper Stat, about 10 bucks, and 70% distilled water to 30% coolant. If and when it gets colder out in your area, then switch to 50/50 coolant seasonally to better protect your block from freezing.

No, I would not put electrics on a true LS6 car. The factory system will easily handle the cooling if functioning correctly.