[260]

I flushed out the system and put a 180 thermostat.It is all stock and timing is set at 4 degrees BTDC.I run a mix of 5 gallons 110 octane to 10-15 gallons 93 octane.After 10-15 minutes of driving temp will reach 230.Why is it running so hot?

 

[Harley]

110 octane in a stock motor? If you don't
have the compression ratio to utlize the
slower burn rate of high octane fuel. It
could be over heating the exaust valves.
Check headers/manafolds for color.
The reason high octane is used in "high
compression" engines is that the octane
slows the burn rate to aviod detonation.
could be that it's so slow that it's still
burning fuel when exaust valve opens(theroy).
Try a lower octane for a while.
Harley
TBS Machine

 

[260]

Harley,
True,my motor is stock,but it has 11.25 to 1 compression.I dont run straight 110.I mix 5 gallons of it to 10-15 gallons of 93.I figure this gives it around 100 which is what it was designed to run on.I dont drive the car everyday so I dont mind putting the extra $ into the right gas with the right timing set.

------------------
Dean Ciampi
Autumn Gold 1970 LS6 Chevelle
Team Chevelle Gold #52 Aces #3094

 

[1bad67]

Sounds like a lean condition. How do the plugs look. If the radiator is a good 4 row and timing is correct I would look into air fuel ratio. Also what is the outside temp when the motor hits 230?

 

[260]

Outside temp is in the 90s

------------------
Dean Ciampi
Autumn Gold 1970 LS6 Chevelle
Team Chevelle Gold #52 Aces #3094

 

[283v8]

Give more info Eg: what type radiator? Fan shroud? what type of fan?? Fan clutch??? Belts tight?? Type water pump?? New or old hoses?
Possibilities: Loose belt, seizing pump, low fluid, air pocket, poor airflow, fouled radiator, Collapsing hose - - - - -
When did this start ? What have you changed that could cause it ??

------------------
"Let me live in a house by the side of the road and be a friend to man, - with a garage and a smallblock Chevy"

 

[260]

4 core radiator...Clean and just serviced.Big block pump#3969811...flows well and good bearings.Hoses and belts are in good condition.Declutching fan is fine.Standard shroud fine.I do live in Florida and it has been getting in the upper 90s.Car can idle without going over 210.When I take it out to play it will get up to 230.

------------------
Dean Ciampi
Autumn Gold 1970 LS6 Chevelle
Team Chevelle Gold #52 Aces #3094

 

[Dave Birdwell]

If it will sit and idle and not overheat, then I would say to try advancing the timing. I had a stock LS5 that didn't like less than about 16 degrees of initial advance (vacuum advance unhooked)
If you're running good gas, then you can try bumping the timing up without worrying about detonation. Cheap and easy to try.
Dave

 

[Tom Howard TH]

I had that same problem many moons ago with my LS6 and believe me it was only the radiator cap. The cap should be #15 and it was, but it had weakened and was boiling. Check to see if you have suffecient pressure on the hoses when hot. Then I would look at the radiator. On 90 degree days I run about 190 - 210. Live in Md. let us know what you find. Good Luck....

 

[Gene Chas]

I think DBirdwell hit it, bump the timing up to 6-8, or as far as she'll go Mr. 110 octane. Advancing the timing could cool things out a bit.

 

[Steve A]

You mentioned the radiator was cleaned. Did the shop "boil it out" and flush it, or did they "rod" it out? Rodding it out involves removing an end tank and actually running a thin steel rod down each cooling tube to removed the build up Basic cleaning at a radiator shop will not get out the heavy deposits. My car ran about the same temp in 45 degree weather, I had the radiator re-cored, and it runs nice and cool now.

 

[260]

Dave,
Seems like you hit the nail on the head!I am running about 8 degrees and notice an improvement.Hottest it got after a few hard passes was 210 and thats in 90+ degree weather.Personal thanks!

------------------
Dean Ciampi
Autumn Gold 1970 LS6 Chevelle
Team Chevelle Gold #52 Aces #3094

 

[Gene Chas]

Gold star to Mr. Birdwell! Good work.

Gene Chas
Gold #62
'67 SS427

 

[Dave Birdwell]

Thank you, thank you...Always glad to know I can help out!
I hope MY LS6 runs cool!! Can't wait to feel that raw Big Block power!!!
Hey Dean- Another thought came to mind...do you have the TCS system hooked up to the distributor?
This system could cause something similar, as the vacuum advance gets cut off after the car warms up.

 

[260]

Dave,
TCS is hooked up.I Replaced the solenoid not too long ago.All seems fine in that area.Cant wait till winter!I know this is when all of you guys up north put the cars in for hibernation.Not so down here in the south!This is when cruzin is cool and motors run best!This LS6 don't like this 97 degree Florida summer heat!!!!!

------------------
Dean Ciampi
Autumn Gold 1970 LS6 Chevelle
Team Chevelle Gold #52 Aces #3094

 

[Gene Chas]

260, I know it stinks having to put the cars up. Ah, another reason to open a branch office in FLA.

Go SABRES!

[This message has been edited by Gene Chas (edited 06-15-99).]