Overheats at speed

Hi , this Barracuda of mine has always run hot on the open road, it can idle around town in the middle of a scorching Aussie summer all day and sit at 180 but get it out on the open road at 3000 rpm and it just keeps climbing. Seen 210 last night in cool air.
Engine is a half full 440/547 with Indy heads, tune is good, has large ali radiator, electric pump, powerful twin fans with cowl, using water wetter and I also have a larger engine oil cooler.
I can’t remember if I have a thermostat with small holes or a reduction spacer in there at the moment but know I have run both.
Any tricks ??

Gonna tell you right now, it's your electric water pump.

Overheating at speed is almost always a water flow issue.

Ok but looking in the radiator you can see the turbulence of the water moving. Today I am goin to try taking out the thermostat or restriction and test drive.

toss the stat just for a test (1) day. Are you sure the rad ain't partly clogged. I'm assuming timing/mixture are in the ballpark (I'm not leaning toward those 2, just sayin). keep us updated.

it is going to be 1 of 2 things then if it idles fine around town.
I have never used an electric pump, but it is possible.

But my bet is the fans and the fan shroud.

Put a cut off switch to the power to the fans. Once you are up to speed turn them off. I Bet it cools down just fine after that.

The solution if that is the case, is to cut some flaps into the shroud, that are hinged. Feets showed me that when we used the maxima fans. You cut out some rectangular holes into the shroud and then hang flaps over to cover them.
At idle, they get sucked shut, at speed, the blow open to alllow more air flow.

This guy gets it!^^^ Overheating at speed is almost always a coolant flow issue....overheating at idle/low speeds is almost always an airflow issue. My guess is that electric pump is flowing the same at idle and 4000 rpm. Works at idle not at 4000 rpm. Belt drive pump changes output based on rpm. Just my thoughts. Good luck!

Yup, either not enough coolant flow under demand, or airflow blockage.
Some of those electric fan shrouds are essentially a box that will block airflow at speed.
If you can try a faster pulley ratio and/or a shroud with flaps that open at speed, do so.
I'm assuming your lower hose isn't collapsing at speed, and there's no blockage elsewhere in the coolant flow.

Electric pumps usually move at one speed, if the hose was "collapsing" it'd do it whenever the pump was on.

The thing about electric pumps is this, they are designed for dragstrip use and in that application they can be useful. On a street driven ride it's just a problem waiting to happen.

Thank you for your thoughts guys.
Have just been working on it, pulled the T/housing to find NO thermostat in there, (I could not remember if it had one or not), I purchased a 180 High Flow thermostat and fitted. Bottom hose was one of those ribbed flex type hoses with spring in it, I purchased a new normal bottom hose with spring, also new red coolant.
Test drive, temp reached 185 quickly and still went to 210 but took a bit longer to get there.
Will look at cutting holes and adding flaps into the plastic fan shroud next day off, might even put another gauge on just to be sure.
Sniper, going back to a belt pump is a major operation that will mean changing power steering pump and alternator locations, you may be right but hope not
Is 210 too hot ?
Again thanks for your input .

Installing a front airdam will make the radiator do its job better by the vacuum under the engine, helping expelling hot air.

A half-filled engine block might need a bit more help to keep cool when working.
What's the ignition timing at those rpms?
Do you run a vacuum advance?

The electric fans could indeed work as a blocker at higher car speeds. But that would mean the radiator is 'marginal' at best already.

210° leaves hardly any margin for error in case of mishap.
I never want to see 190+ on any my engines. I have one car borders that number, but it's engine isn't optimal.

Locked up at 35 deg

Sounds to me like you are trying to run a race car on the street.

locked timing, electric pump, etc.

A lot of things that make sense at the strip fail to make it on the street, which it looks like you are finding out the hard way.

35 degrees might make sense at WOT throttle but it doesn't make sense anywhere else.

At cruise you want more timing than that, which is why there is vacuum advance. Probably part of your running hot issue as well.

Another thing to look at is your timing. Running 3000 rpm With very little load is where a vaccum advance is needed. If you only running a distributor with mechanical advance, could be contributing to an inefficient overall cooling system.

Yes mate the car is a bit on the race side, will go 9.90’s and I understand I am asking a lot but I’ll get there.
You say I need more than 35 degrees at cruise ?
The car drives beautiful and smooth .

Are you running the stock diameter crank & water pump pulleys? Can the air coming into your grill go around the radiator to get past it without flowing through it? Sorry, I posted before reading the guys posts, which are on point. I also agree it's likely the electric water pump.

Yes, vacuum advance beyond the 35* total will allow the motor to run cooler at road speed. If you switch you ignition box to a programmable one like the MSD Programmable 6, I believe you can add a simulated vacuum advance feature, but I have not done it.

Except for that running hot thing.

Yes, you really ought to advance the timing at cruise, maybe that programmable setup mentioned can suffice, not familiar with it so I can't say.

Just my here. Seeing as how you are running a 1/2 fill block on the street, you might want to consider an oil cooler and/or oil temp gauge.

Randy

is the hood sealed to the core support ? that will maximize the air going through the radiator opening instead of just "spilling over" the top of the support.
are your electric fans aftermarket, or some type of OEM ? if aftermarket, i have found them to be optimistic at best on amount of airflow. i ONLY use OEM fans in EVERY electric fan application. they are far and above ANY aftermarket fan made. be warned, however, they require many amps to operate, so an upgraded electrical system is a must.
they also consider high speed airflow, so their shrouds are designed for airflow at speed, while the aftermarket fans and shrouds are not.
lastly, puller fans are way more efficient than pusher fans.
please keep us updated.

second to take the shroud off. its limiting aif flow through the rad.

See original post mate, I am running a larger oil cooler and I do have an oil temp gauge , oil temp was about 220/230 when water was 210

I have 3 different hoods, one on at the moment is a glass cowl style hood that would not be sealing much at all, it’s on there to hide the twin 950’s on the tunnel ram from the police 🙄 maybe there is something in this because it is all of a sudden a bit hotter than before.
Fans are Ford something and suck like crazy

Update,,,
Purchased a temp gun, ran the car at home up to 210 and had my son shooting all the right spots with the gun, on the brass fitting that the sensor is in, on the front of the ali heads and even let the pressure out of the radiator and checked the temp of the water, 170 was the highest reading we could get while the gauge was showing 210, had already replace the sender so the gauge is *ucked yeah ??

sure looks like it from here ! [i finally got the pair of x-ray glasses from the comic book add i ordered all those years ago to "see through" women's clothing ! :biggrin
without going back through the thread, was that even mentioned to try an IR gun ? that's usually the first thing i do with heat issues.
i'm so dumb sometimes ! and i get dumber the older i get..........

Be aware that the IR temp guns should only be used as an indicator as they need to be calibrated for the surfaces they are reading. being off by 40 degrees is unlikely unless you have a bad gun or heavily coated surfaces.

The only way to know for sure what the temp is doing is to used a thermocouple probe installed a closely as possible to the thermostat housing. The probe is then coupled to a digital meter that will read accurately to a 1/10 of a degree or better. They also respond very quickly. I use this method exclusively when chasing temp issues. One can probably get an entire setup for less than 100.00. A lot of digital volt meters now come with this feature/accessory. You can also buy extensions for the probe lead that will allow you to place the meter in the car so you can watch it as you drive. Also make sure you get the correct probe and extension types as there are two different ones. Type J and Type K. Mixing the probes, leads, meter will skew the readings.

In my testing I have found more than one "name brand" gage to be doing exactly what yours appears to be. It is also typical for them to go farther out of whack the warmer the coolant gets.

then, it can boil down to [yes, pun intended ! ] just how hot is "hot" ?
"hot" to me is 220+ with coolant loss in old stuff, while that temperature in newer vehicles is just running temperature.
with a good cooling system, i would rater see 205-210, than 160-170. but that's just me.
along with the elevated temperature however, the tune MUST be optimized for best results, or bad things WILL happen.
if one doesn't take the effort to do so, or can't for whatever reason, then it's imperative to keep the temps low.
wild swings from idle to cruse need to be looked at because a steady temperature is best.
just my opinion, your mileage may vary.

"over heating" is kinda relative . . . . when the FIRST "Pacific Nationals" (mopars at the strip now) were held in Vegas, in AUGUST, it was HOTTTT outside for sure, think like 110 F in the shade !!! . . . anyhow, I drove my 300Hurst with the AC thumping out cold air, at speed on the highway - was running 205-210 F getting up to 240F at the top of hills, but cooling back down to the 205-210 . . . was not pushing anything out of the rad . . . was factory rad/shroud/t-stat and I had put mechanical temp gauge on the car. Sure it was hot, but no pinging or adverse effects to the old 440 - and NO WAY I was going to NOT use the AC !! . . . .and today - the cars are running at the 205-210 F temps as "normal" . . .

if i understand thermostats correctly, they are not fully open until 10-15 degrees above their rating. in other words, a new car stat coming with a 205 degree rating will not reach full opening until 215-220 degrees.
if i understand heat transfer correctly, the larger the difference in temperatures between the coolant and the surrounding material[s] [the radiator structure], the better the heat transfer, thus the better the cooling system will operate.
back in the day, a common factory T-stat was a 180-195 unit, so it is conceivable it was not fully open until 215 degrees.
i too, used to be a believer in keeping temperatures in the 160-175 degree range, but i have had much better running success utilizing higher temperatures than lower ones, so that is my preference now.
still, there is more to it than just placing a piece of cardboard in front of the radiator to bring the temperature up.

I was there, it was crazy hot on the gravel infield of the race track.

On the cooling, if the car cools back down when you slow down, then most likely it is a water pump or air flow problem. If it will not cool down unless you shut it off and let it cool, it is likely getting air locked. Still a flow problem but caused by trapped air in the system. When I first got my Coronet, it would do that at high speed and not recover, but it had a bad head gasket.

OK guys, got home from work and fitted a new temperature gauge, AutoMeter #4454 ( $360 Aussie FFS ) , car now running at 180 with a 190 maximum @ 3500 rpm on Highway.

YES !!!!!!!!!!!!!!!!

Thanks for your help.

You sound stoked (my best Australian!).

RR ..... we should take up a COLLECTION for our Aussie member .... 360$ for a water temp gauge ??!!

Yes somebody sure came out ahead on that one.

I admire your dedication!

And do agree with FFS, that seems crazy.

Unfortunately not the first time I've seen Autometer with pricing way out of line.

glad it was an easy fix !

Hahahaha, I replaced everything else first .....

i wonder witch guage is bad.

A man with two watches never knows what time it is.

On the other hand, a stopped clock it right twice a day.

The two most common things I find when a car overheats at speed are this.
One lower hose collapsing, and too lean in the fuel. Check the plug color!!