Hot-running LS6

[Keith Tedford]

Our '69 L78 4:10 geared Chevelle runs in the 205 range on the highway in hot weather. You are running a lot of rpm at 60 mph. The temperature will stay below 200 at idle. Never had a problem in 21K miles. Total timing will make some difference.

[moparts]

Things that help:

good radiator cap.....for every 1 lb pressure the boiling temp raise is aprox. 2 degrees.

16 lb cap working properly will raise boiling point to aprox. 244 degrees.

Car operating at 200 is still 44 degrees below boiling point.

Antifreeze/antiboil raises this boiling point also.

Higher octane fuel makes alot of difference...not sure how much but the difference between 96 pump and 110 race fuel is tremendous.

Less timing lowers operating temp but also hurts performance..there is a happy medium

Things that hurt:

Low pressure or leaking radiator cap.

Weak antifreeze

Low octane fuel

Lean fuel condition

Too much timing


I have seen alot of times that someone will take a thermostat out of a car and it run hotter....so in saying that...if the flow of water is too fast it doesn't have time to cool properly, but on the same hand if it is too slow it won't either. Use one of the new

Clutch fan should not affect any driving speeds over 40 mph or so.

And last but not least.....DON'T TRUST YOUR GAUGE....either check temp with a thermo gun or an old fashioned thermoter in the rad.

Hope some of this helps.

[olredalert]

------Us guys with big block Corvettes have suffered forever with different over-heating issues.All of the above mentioned are important.The infrared gun will really help you out.Shoot it somewhere near the sending unit and then check against the guage.The sending units sold today and even old ones are calibrated differently than the original one that came in your engine.You may be actually running cooler than you think.If you find this to be true get a Corvette Central catalog(or www.corvettecentral.com).In there somewhere you will find a little infinetly adjustable inline electrical "dohickey" (technical enough for you?) that,once installed,you can adjust the guage reading to read correctly.It doesnt cost too much and will keep your guage reading correctly forever.Hope this helps as it is a real slick little unit..............Bill S