[roger1]

I'd get a stock shroud, 7 blade fan and new clutch. Sell the electric fans on a forum or ebay.
If you have your heart set on electric, get a new shroud. Ledfoot racing makes a shroud for a '70 GTO that mounts dual 14" fans. I suggest Spal fans and don't wire them like you have now. You should be running a temperature sensor.

[Scott65]

As an experiment, see if it runs hotter, or cooler on the open highway. That will tell you if the fans/shrouds are hurting or helping.

[Chris65LeMans]

Before you start throwing money and parts at it, work on the stuff you can do for free by turning wrenches:

A. water pump clearanced?
B. What does your tune look like?

[geeteeohguy]

Originally Posted by Chris65LeMans

Before you start throwing money and parts at it, work on the stuff you can do for free by turning wrenches:

A. water pump clearanced?
B. What does your tune look like?

Excellent advice, and A is the place to start when you have ANY hot running concerns. Eliminate/verify pump clearance problems before you do anything else if you want to save a ton of time, and a ton of money.

I run 160 T stat's in both my GTO's as it is over 100 degrees many, many days a year where I live. Since I got a Lectric Limited temp sensor, my '65 GTO runs 185-195 with the original Harrison 4 row tripower radiator, fan shroud, and upgraded 19.5" GM clutch fan. My '67 Convertible about the same, with the original Harrison 4 row HD radiator and an 18" GM flex fan off of a '69 Caddy. These cars will run tens of thousands of miles at 220 degrees with no harm at all....as long as they don't detonate. I've found Pontiacs running at 180-190 are less likely to rattle than ones running 210-220.

[Formulajones]

Just an FYI with that cold case dual electric fan setup....

Even running on the highway wouldn't cool the car down. Once it heats up, it stays up there, the fans come on and never shut down.. That was my experience when dad tried that setup. I had the fans set to come on at 185, they would come on, even on the highway, and the temps would push 200 and stay up there going 65 mph.

Once those electric fans came off, the stock shroud went on with a stock 7 blade clutch fan, all that stopped, now can't even get the car hot.

To put it simply, the only conclusion one can come to with a back to back test like that is the Cold Case dual electric fan setup just did not allow enough air to pass through the radiator, even at highway speeds. I even tried cutting rectangular holes in the aluminum shroud, covered with rubber flaps that in theory should open at highway speeds, and suck shut when the fans come on.

No dice, didn't work either. I simply couldn't cut enough holes that were big enough to do any good without being a total eye sore to look at.

[1965gp]

Tanks for that Formula- I was wondering if cutting the shroud would help- there is my answer

[1965gp]

I have not clearanced the water pump- I’m not familiar with that. I will search the cooling forum I guess?

[Scott65]

Have you verified that temps get hotter on the highway?

[promptcritical]

Does painting the radiator noticeably affect cooling?

[padgett]

Sure sounds like a clogged radiator to me, what does an IR gun say ?

[MUSLCAH]

Originally Posted by 1965gp

I have not clearanced the water pump- I’m not familiar with that. I will search the cooling forum I guess?

Go to today’s posts…it called…chaulk one up for the cast impeller

[1965gp]

I haven’t had a chance to get it out today- been doing kid stuff all day do no- not verified at higher temps

[mgarblik]

The clutch fans move a huge amount of air coupled with a shroud. My 455 in a 62 Catalina with an OE style copper/brass radiator runs 195 degrees max in 90+ degree humid Ohio weather. As soon as I can get on open road and cruise, it comes right back to 180. You are right, 210 won't hurt the engine but it will run better at 180-185.

[1965gp]

Took it to pick up my daughter from cheer practice this evening. About 15 miles round trip? Car got up to about 195 but on the open roads at 50-55 the temp didn’t drop at all. Not once. I’m thinking that (as others have said) the shroud definitely restricts the natural air flow

[mgarblik]

Originally Posted by 1965gp

Took it to pick up my daughter from cheer practice this evening. About 15 miles round trip? Car got up to about 195 but on the open roads at 50-55 the temp didn’t drop at all. Not once. I’m thinking that (as others have said) the shroud definitely restricts the natural air flow

If you want to verify for sure, can you get right on some roads where you can run 50-55 MPH without sitting and idling? If that's possible, take that electric fan rig off and just go drive it without a fan. It should run cooler at 50-55 without any fan if that electric set-up is blocking airflow in a major way. If that sounds risky to you, stick an engine driven fan on for testing.

[chrisp]

195 is a good temp.

[Schurkey]

Originally Posted by PunchT37

Modern cars do run at 200 to 210. BUT, they don’t have carbs with low pressure fuel boiling problems. These carb’d engines need to be run cooler these days with pump piss.

Modern cars run at 210 because that's what the fan controller is programmed for.

The fan "controller" for the original poster comes on with the ignition. There's no excuse for engine coolant temp to be much higher than the thermostat rating AT IDLE OR CRUISE. (It would be higher under load.)

If the engine has already maxed-out the thermostat and cooling system under light load, there's no reserve capacity for operation under heavy load.






It takes a big-deal electric fan system to keep up with a pretty common OEM fan, clutch, and shroud system. Good electric fans do exist, but they're either taken from OEM-engineered vehicles at the Treasure Yard, or someone paid big money for an aftermarket system. Typical aftermarket fan setups are on the skimpy side; and the shrouds tend to either not fit well, and/or block airflow at higher speed.

[70GS455]

If you have plenty of cooling system capacity, water temps should always run within 5 to 10 deg max of the t-stat rating.

If a modern vehicle is running 210 deg, it normally has a 205 or 210 deg t-stat. If not, it's overheating.

Sent from my SM-T817V using Tapatalk

[nikrnic]

The engineers must of known something back in the day. My 66 cooling system is bone stock. Harrison copper core radiator with a 180° Thermostat, factory shroud, fan guard and 7 blade clutch fan and normally runs at 180° up to 185/90 on the hottest days in traffic. I even played with a few different radiator caps and on pressure testing them the original old born with R15 cap was the only one that didn't lose any pressure.

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[1965gp]

Yea- pretty sure I am going to switch to a factory clutch fan. Everyone here has made really good points.