Cooling question
Thread Starter
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Joined: Jul 2007
Posts: 67
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From: HAMPTON VA
Cooling question
Gents and Ladies
I have question in regards to the cooling of my 77. Ever since I bought the car I have been concerned about the temp that I run at. I have a mildy built 350 running 9.5:1 with Brodix alum heads and roller rockers. The cam is a Lunati with 280, 540/540 with Weiand Stealth Manifold and a 670 Holley. The radiator is big aluminum 4 core that is failry new along with a brand new water and temp sensor X2 . The gauge constanly climbs to the 260 range by the time I drive it for 20 mins or so. There is no thermostat installed either. I have a direct read radiator cap and it reads usually in the 210-220 range when driving. The fan is a 6 blade flex and sits almost dead center of shroud. Based off the data above should I be running this warm?
My only other options are to pull the heads and ensure the head gaskets are properly configured for the block or install a electric fan. ANY RECOMMENDATIONS?
I have question in regards to the cooling of my 77. Ever since I bought the car I have been concerned about the temp that I run at. I have a mildy built 350 running 9.5:1 with Brodix alum heads and roller rockers. The cam is a Lunati with 280, 540/540 with Weiand Stealth Manifold and a 670 Holley. The radiator is big aluminum 4 core that is failry new along with a brand new water and temp sensor X2 . The gauge constanly climbs to the 260 range by the time I drive it for 20 mins or so. There is no thermostat installed either. I have a direct read radiator cap and it reads usually in the 210-220 range when driving. The fan is a 6 blade flex and sits almost dead center of shroud. Based off the data above should I be running this warm?
My only other options are to pull the heads and ensure the head gaskets are properly configured for the block or install a electric fan. ANY RECOMMENDATIONS?
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
You should not be running at that temp. I would install a thermostat immediately. This could be your problem as water can run through the rad too quickly to properly cool. Also, you can damage your engine running without one as sludge can be created if the engine is not brought to operating temp. I would probably go with a 180 or 195 degree thermostat. Another possibility among other things is that your gauge is incorrect. Anyway, you need a thermostat. Good luck.
8th Gear
Joined: Mar 2005
Posts: 8
Likes: 0
I struggled through this issue with my big-block. A brand new 4 core aluminum radiator, 6 blade fan and the correct shroud and shroud "gaskets" sill didn't provide enough air flow. I finally added a twin electric fan and it's proven to be the solution for me.
Melting Slicks
Joined: Mar 2007
Posts: 2,100
Likes: 12
From: Frederick Maryland
Yep...get a thermostat. Also check with a thermometer or laser temp gauge to verify you are actually running that hot. You could have a bad sending unit.
I'd dump that flex fan and install a correct fan and clutch assembly. It will be more efficient than the flex fan and quieter at speed.
The direct read radiator cap and the temp gauge could well be different...they're taking reading from different areas of the cooling system, but that's quite a difference in indicated temps.
Does your lower radiator hose have a reinforcing spring in it? If not, the lower hose could be collapsing at speed making the coolant in the block run that hot from lack of circulation.
Other things to look for are whether the seals around the radiator in place properly...plus the spoiler under the front end. If not, they are two of the biggest causes of a C3 running hot.
I'd dump that flex fan and install a correct fan and clutch assembly. It will be more efficient than the flex fan and quieter at speed.
The direct read radiator cap and the temp gauge could well be different...they're taking reading from different areas of the cooling system, but that's quite a difference in indicated temps.
Does your lower radiator hose have a reinforcing spring in it? If not, the lower hose could be collapsing at speed making the coolant in the block run that hot from lack of circulation.
Other things to look for are whether the seals around the radiator in place properly...plus the spoiler under the front end. If not, they are two of the biggest causes of a C3 running hot.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
confirm actual operating temps with an IR Temp Gun.
as already mentioned, install a quality t-stat (why in the world did you not install it in the first place?), I recommend either the Robert Shaw or Mr. Gasket 180º t-stats.
Next, pull the flex fan and install the correct fanblade and fan clutch. Ptoper position of the fan is 1/2 in 1/2 out of the shroud, NOT in far enough to be in the center of it.
Next, do you have all the radiator and core support seals in place and the airdam under the nose?
check your timing and vacuum advance system for correct timing settings and correct operating of the vac adv and that the vac adv is connected to a full manifold vacuum source.
Once that is done determine WHEN the overheating is occuring (assuming it really is after checking it with the IR temp gun). Is it at idle / slow speed driving or is it at highway speeds? This will help determine what part of the system may be at fault.
as already mentioned, install a quality t-stat (why in the world did you not install it in the first place?), I recommend either the Robert Shaw or Mr. Gasket 180º t-stats.
Next, pull the flex fan and install the correct fanblade and fan clutch. Ptoper position of the fan is 1/2 in 1/2 out of the shroud, NOT in far enough to be in the center of it.
Next, do you have all the radiator and core support seals in place and the airdam under the nose?
check your timing and vacuum advance system for correct timing settings and correct operating of the vac adv and that the vac adv is connected to a full manifold vacuum source.
Once that is done determine WHEN the overheating is occuring (assuming it really is after checking it with the IR temp gun). Is it at idle / slow speed driving or is it at highway speeds? This will help determine what part of the system may be at fault.
Thread Starter
Advanced
Joined: Jul 2007
Posts: 67
Likes: 0
From: HAMPTON VA
Thansk for all the in-put so far. I will install a new 195 t-stat and go from there. Last summer I used a IR gun from work and shot at the T-stat housing and the radiator, the temp was reading just over 180 with a 165 t-stat installed. I have noticed one thing is that I do not a front spoiler and thought that might be directly attributing.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Thansk for all the in-put so far. I will install a new 195 t-stat and go from there. Last summer I used a IR gun from work and shot at the T-stat housing and the radiator, the temp was reading just over 180 with a 165 t-stat installed. I have noticed one thing is that I do not a front spoiler and thought that might be directly attributing.
last summer is a year ago and the systems conditions may have changed so I'd shoot the temps again with the IR gun.
not having the airdam will most definitely be an issue. The C3 cars are bottom feeders for air intake and not having the airdam is probably causing you to lose at least 50% of the air flow to your radiator
Burning Brakes
Joined: Apr 2007
Posts: 1,028
Likes: 1
From: SOUTH ELGIN IL
Are you heating up that much at idle or while driving at speed? I changed out my stock fan w/ clutch for a flex and immidiately watched the temp climb over 250*. Pulled it off and went back to the stock fan w/ clutch and temps went right back down into the the 200* range.
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