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View Full Version : How Hot Should My Big-Block Run?

THE BRONZE
04-17-2002, 02:08 PM
The 427 in my 69 Chevelle runs between 200-210 degrees, and climbs to about 220 at long lights when its over 75 Degrees out. Is this too warm?
LL6
04-17-2002, 02:36 PM
Borderline yes. Thirdgen were designed to run hot, not older 60's cars. Can't remember...are you running a clutch fan or flex?
THE BRONZE
04-17-2002, 05:21 PM
Flex.
THE BRONZE
04-18-2002, 11:51 PM
C'mon B-, any opinions here?
RobP
04-19-2002, 12:03 AM
I really don't know how warm my 71 Impala 402BB runs but I do run a lower PSI cap just to protect the radiator and hoses. The higher pressure cap raises the temp that the water will get before it boils. I'd rather have an early boil than a later boil. What kinda of radiator do you have? Headers coated or uncoated? Underhood heat could add to the temperatures. What thermostat are you using? Stock waterpump or aftermarket one? Your lower hose is not collapsing is it?
WS6 VERT
04-19-2002, 12:05 AM
Sorry, I know squat about BB's but I imagine its the same for SB's.
THE BRONZE
04-19-2002, 12:08 AM
Stock waterpump, factory radiator for an AC automatic (No AC though),180 thermostat( I think, or a 160), and the hoses are not collapsing. I'm running painted headers, and the water flow seems to be fine.

She isn't boiling over; just curious if this is too hot.
LL6
04-19-2002, 12:30 PM
You will need to verify the accuracy of the temp gauge. It could be off...
THE BRONZE
04-19-2002, 02:46 PM
New guages, and the old ones showed much the same.
86IROC
04-20-2002, 12:00 PM
Bronze - one of my first cars was a 69' SS 396 Chevelle. It had a .060" over 396, ported dart square port heads, 2.25"/1.88" valves, 2.125" headers/coated, 4 speed, 4.10's, etc. It never ran over 195 degrees. I would look into ignition timing, and the heat range on the spark plugs. Also, you said the carb was wrong, maye it's too lean. Just tossing out some suggestions. Let me know what you come up with.
THE BRONZE
04-20-2002, 02:40 PM
If anything, I think she's running rich, but I hope to know soon enough. Thanks for the information about where the temp should be.
86IROC
04-20-2002, 05:13 PM
NP Jim, I will have to ask my pops if he thinks running rich will do it. It seems to me that too rich or too lean will do that.