I have a 350ci and was wondering how hot was too hot; as i am regarding to engine damage. at what temp. do you start blowing head gasket, melting piston rings (really need to know this one), spin bearings, breakdown oil, etc. Please give me a close approx. IE at 260 deg... at 230 deg.... thanks for the help.

------------------
1970 Chevelle 400hp 350ci, th350, locking 10bolt. Go Earnhardt Jr.! "The importance of material things is invaluable if you loose the things essential to the spirit of life."

According to the '65 shop manual operating the engine at temperatures up to 243 deg F will not damage the engine. However, that is rather hot and I should think that your cvooling system is defective or something els is wrong if the coolant can not be maintained at 200-210 on a hot day.

I remember being on the Sacramento freeway in my buddy's '70 Nova when the needle was pushing 260' +. Then we heard a loud "bang!" and the distributor cap had blown clear off the dist., the rotor was melted and there was a hole through the points! (non-HEI). So I think catastrophic failure is just a matter of time when your pushing those kind of temps.

------------------
'72 Nova
355 L-31 Vortec
TH-350
10-Bolt 2.56 Open, Rally Suspension
Weld Draglites (235/fr 255/rr)
3,071 lbs. w/ Full Cell
--------------------------------------
'70 Chevelle, gutted.

I have tested (in heated oil) my 283 factory sensor for the idiot light. It closes at 266 and opens again at 230.

I decided to mount it in the driver's side head between nrs 1 and 3 sparkplug.

Rob

[This message has been edited by rusty66 (edited 07-09-2002).]

rusty, so youre saying your idiot light will not tell you youre running hot until your car is running 266 degrees??? i think the engine block would melt around the sensor by the time it got that hot! Instead of an idiot light, just watch for the paint on the hood to blister, or for the chrome on the SS hood ornaments to start turning blue... http://www.chevelles.com/forum/smile.gif I had one at 240 once, and they definitely aint happy running even that hot.

First of all, engine temperature basics 101.

Coolant temperatures are not an accurate indicator of actual metal temperatures. The coolant's maximum temperature is it's pressure corrected vapor point.
The metal can be several hundred degrees hotter than the adjacent coolant and survive without damage and live depending on other issues.

Temperatures of critical areas must be determined by checking the metal at a controlled distance from the combustion chamber surface. This eliminates discrepancies caused by the variances in metal thicknesses. This also means that all heads may not give accurate readings at the head sensing point since they vary in castings so much. Be aware of this anomolie.

In my opinion and experience, if you are at 240 mark (measured from an intake point)with all the coolant being retained and stable, I would not worry too much. If you start to push coolant out at high temps, that means that there are pockets of hotspots getting superheated....time to shut it off and cool it down. Also, time to check that you are running at least a 16 -18psi cap preferably.

I have seen as high as 250ish on aluminum headed engines with absolutely no damage and work fine. But, stability and coolant retention is as big an issue as the temperature. While you coolant can show 220 degrees, the expelling of coolant at that temperature means either poor cap issues, and/or hotspots forming which could cause detonation in your engine...ouch.

In some circle track venues I have seen temps read 260 thru 30 laps with no damage either. So, it's a combination of things and more relative than one would think.

------------------
Steve Jack
-Concept One Pulleys and Brackets
-Engineering & Marketing Technologies
-Northern/Southern Rodder Magazine's "Jack'Stands" technical column author/originator