74 big block operating temperature
Thread Starter
Racer
Joined: Apr 2002
Posts: 274
Likes: 0
From: tarentum pa
74 big block operating temperature
i have a 74 vette with a mildy modified 454 in it bored .60 over. i'm routinely running around 220 -225 degrees on the temp guage. is this a safe reasonable temp? would you guys consider this overheating? i'm running a 185 degree thermostat if it matters.
Pro
Joined: Jan 2006
Posts: 599
Likes: 0
From: New York
Mine hits those #'s quite often n I never had a problem....As we speak she's in the shop on a unrelated problem but my guy is going to seal up the front a little better so more of the air is directed directley at the radiator...U know these big blocks generate tremendous heat so we will always have that cooling issue....Jerrylee///
Burning Brakes
Joined: Jul 2001
Posts: 853
Likes: 0
From: Foxfield, Co
The owners manual for my 72 states:
"During normal operation, gauge will indicate around the 230* mark. If the gauge indicates 250*, the engine is overheated."
That is what the manual says but running a constant 230* would worry the he!! out of me.
Greg.
"During normal operation, gauge will indicate around the 230* mark. If the gauge indicates 250*, the engine is overheated."
That is what the manual says but running a constant 230* would worry the he!! out of me.
Greg.
Drifting
Joined: May 2005
Posts: 1,909
Likes: 6
From: Lake Arrowhead - Georgia > 72 Base Coupe & 74 BB Roadster
My 74 - LS4 has the original radiator. (non AC car) It has been boiled and re-cored. I have replaced all the rubber on the support and radiator shroud. Its sealed tight as a drum. Stock fan and clutch. With a 180 stat ... it stays on 190 all the time.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
Our 69' 427 car also runs 190* most of the time. Sometimes on the highway (3000-3200rpms continuous) it may get close to 210*...bring the rpms back down to 2000-2500 or less, and it cools back down to 190*, even bad traffic jams it stays 190-200. No ac though.
Stock radiator/fan/clutch/expansion tank.. Not sure about thermostat, I think its a 160*.
Our 67 427 runs about the same way. All stock components
Stock radiator/fan/clutch/expansion tank.. Not sure about thermostat, I think its a 160*.
Our 67 427 runs about the same way. All stock components
Tech Contributor
Joined: Jun 2004
Posts: 20,931
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
What's your spark curve like? My '69 used to run hot when I first acquired it (bone stock). I've still got the original radiator in it, but with a decent advance curve in it now I rarely have overheating issues. Also, do you know for certain that your gauge is accurate?
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Your temps are getting higher than you should be seeing, if everything is right.
First, is your radiator sealed to the hood and your lower extension in tact? How about your fan? Sender ? Thermostat? (I test all of mine on the stove with a candy thermometer before use, and I've found many an auto parts store unit that didn't operate properly.) Or, does your rad just need a good servicing??
If that's all good, is your carb running too lean, or your ignition timing too retarded? What about your bearing clearances and oil pressure? Finally, is the dynamic CR of your "mildly modified" mill perhaps near or beyond the upper limits for pump gas??
Should none of these items be contributing to the heat, I'd consider a higher capacity aluminum rad, and upgrade to electric fans.
Q: Did the '74 have the two or three hole lower rad panel??
First, is your radiator sealed to the hood and your lower extension in tact? How about your fan? Sender ? Thermostat? (I test all of mine on the stove with a candy thermometer before use, and I've found many an auto parts store unit that didn't operate properly.) Or, does your rad just need a good servicing??
If that's all good, is your carb running too lean, or your ignition timing too retarded? What about your bearing clearances and oil pressure? Finally, is the dynamic CR of your "mildly modified" mill perhaps near or beyond the upper limits for pump gas??
Should none of these items be contributing to the heat, I'd consider a higher capacity aluminum rad, and upgrade to electric fans.
Q: Did the '74 have the two or three hole lower rad panel??
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