[Speargun]

If your car has cooling issues, especially first gen Firebirds, step in inside!

My journey to keep my '67 Firebird cool in the Florida heat has been a long and expensive one. Along the way I have discovered what works and what doesn't, at least for me. I'm by no means a cooling expert, but maybe some of the things I've learned may help someone find the right combo to keep their car cool & happy.
Since I know the ’67 Firebird, I’ll focus on that, but much of this information can apply to any model.

I bought my ’67 bird in January 1990 and have had trouble keeping it cool, with anything much more than a stock engine, ever since. I completed its restoration and put it back on the road on 1/25/2017 and that’s when my cooling education began.

First Gen Firebirds:
I feel that the 1st gen Firebirds suffer cooling issues due to a small frontal area and a small radiator core. Even the 1st gen Camaro has a larger opening and less obstructions in front of the radiator. While it may be good enough for stockish engines, once you start creating more HP & heat, you’re going to need more air flow through the radiator to get rid of that heat. And THAT, is the short answer to keeping cool; More Air Flow!

I would recommend to any first gen owners looking for better cooling to consider adding the upper baffles that came on 400 & AC cars and the lower baffle. An air dam, aka chin spoiler, can help in directing air through front of the car as well as cleaning up some of the “dirty” air under the car which could help add mpg.
Sealing the gap between the radiator and core support helps. I think that there was a factory rubber seal around the core support opening, but some of the black foam pipe insulation from the hardware store stuffed between the radiator & core support, does a good job and is cheap.

Thermostat:
Try removing your thermostat. I’ve always observed better cooling with the thermostat removed. Just like we want more air flow, we also want more water flow. “But my grandpa told me to put in a hotter thermostat. That way the water spends more time in the radiator & gets cooler.” While that may work for an oversized cooling system with the ability to remove way more heat than the engine produces, it’s not near as effective when the cooling system is at, or near, capacity.
That said, what works me may not work for you. A thermostat is there to get an engine up to proper operating temperature and keep it there. I might see 3 days a year where it’s actually cold enough to need a thermostat to keep my engine warm.

Beware of aftermarket thermostat housings. Apparently they aren’t machined right inside and it allows your thermostat to get jammed in there crossways.


Water Pump:
Get a water pump with a good impeller design. Then, clearance the divider plate. The tighter the clearance, the more efficient the pump. There are hundreds of threads on this so I’ll not cover that here.

Engine Tune:
Your engine tune can play a big part in your engine running hot. Double check your timing, plugs, and AFR and make sure that everything is where it should be.

Radiator:
If it’s full of scale and rust, it’s not going to work very well. I use to fill my radiator with the garden hose when I was younger; just like everyone else. It was also very common to take your radiator to the shop once every few years to have it rodded out. Now I only use distilled water with the proper antifreeze. I miss the days when there were only 2 different brands to choose from. You had your choice of yellow or green and they both cost about $4 per gallon. Today, you have every color under the rainbow for every different engine make and none of them can be mixed together without causing a low yield nuclear reaction inside of your engine. I spent hours searching the internet and reading all about the different formulas and what engines they were designed for alongside of horror stories of mixing the wrong ones together. I still don’t know if I picked the right one for my aluminum IA engine, but I went with the Zerex G05 formula at $50 for 2 gallons! At least I’m sure that it will lubricate the pump well as the bit that got spilled was harder to clean up that baby oil and twice as slippery.
No matter which brand/type you choose, run 25% to 50% coolant/distilled water to help lubricate the pump and raise your boiling temp a few degrees.

Here’s a link to a review I did comparing 3 different brand radiators:
Champion vs Eastwood vs Cold Case Radiators
TL/DR
Cold Case Radiator won.

Water Wetter & “Waterless Coolant”, IMO, is mostly snake oil. I have tried water wetter a few times and wasn’t impressed. I’ve never tried the “Waterless Coolant” since it’s stupid expensive, requires almost laboratory conditions to install, and your only one blown radiator hose away from dumping hundreds of dollars on the ground and hundreds more for a refill. Stick with distilled water and a regular coolant for simplicity and lower cost.

Radiator Cap:
A properly working radiator cap will raise the boiling point of the coolant to prevent overheating. If the radiator cap fails, the coolant will boil once it reaches between 212* to 230*, depending on your coolant/water mixture. Once it boils, the coolant (a liquid) turns to steam and steam (a gas) is a very poor conductor of heat. Think about standing naked in a 60* room (air=gas) vs being in 60* water (water=liquid). Which one is going to cool you off the quickest.
The addition of pressure, and coolant, will raise the boiling point so when your engine hits 220* while you’re stuck in traffic, the coolant doesn’t boil over and really cause problems. The chart below shows the relationship between pressure, coolant, and boiling point.
BTW, 210* to 220* is not necessarily too hot or overheating with a properly working cooling system, although, I always feel better when it stays below 200*



Fans:
[Breaks out old school can opener & picks up can o’ worms.]

Remember at the beginning of this when I said “you’re going to need more air flow through the radiator to get rid of that heat.”? Well here ya go. Sometimes…. You can solve all of your cooling problems with just the right fan. Forget all of that crap I said above and install the biggest honkin’ fan that will fit.

Of course, that may not work alone and it may take a combination of all of the above to get the cooling system where you need it. The fan, however, tends to make the biggest difference; good or bad.

Before I get into electric fans, let me just say that one of the best cooling systems I had used a 7 blade fan off of a ’76 Chevy camper special pickup. Combined with a good Hayden clutch and a factory shroud, kept my engine in the 190*-200* range on the hottest days.
Don’t discount factory type fans. They move a LOT of air. As a rule of thumb, a mechanical fan will outperform an electric fan any day.

I’ve never been a “fan” of flex fans. I tried one with my current combo and it didn’t come close to cooling as well as a clutch fan.

And while we’re still talking about mechanical fans, DO NOT USE them on a serpentine system. Apparently when you shift or change rpm’s rapidly, the centrifugal force of the spinning fan suddenly slowing down can do, …um… bad things.
V-belts slip; Serpentine belts don’t!



Electric Fans:
The first rule of electric fans: Manufacturers & Sellers LIE!
Don’t even look at the CFM rating. That 2400cfm fan is, in reality, an 843cfm fan once you put it on a radiator. A much better indicator of how powerful a fan is, is the size of the motor & amperage draw. CFM measured at zero static pressure is mostly meaningless and I doubt that many, if any, of the offshore manufacturers have actually performed legitimate measurements. I’ve seen the exact same ‘made in China’ fan with a 120w motor listed as 2600cfm by one vendor and 3200cfm by another.

Electric fans work better as “pullers” than “pushers.”
2 smaller fans ‘generally’ move more air than one large fan.
You need a good shroud.
Use relays and appropriate sized wire.

SPAL electric fans are probably the best made fans on the market. They are made in Italy and used in everything from heavy construction equipment to Cadillacs. You can look up the flow chart for each of their fans that will show the actual CFM at different Pressures. They have different models of the same size fans, but with different motors, so make sure that you’re getting the right one. Bigger is always better here.

Even though Spal fans are good, they are not always enough. I ran a pair of Spal Heavy Duty 12” fans for a while and they did okay, but I had to be careful on hot days (pretty much 10.5 months out of the year) in traffic and that was with the help of a 13” (medium duty) pusher up front.. These were the most powerful 12” fans that I could find, the motors were huge! These fans pulled 40-45 amps running and close to 100 amps at startup! EACH!

[Speargun]

I have recently discovered the fan holy grail.
It’s made by Spal and is used in the 2016 – 2020 Camaro & some 2016 – 2019 Cadillacs. The GM part number is 1581927 (15-81927) Radiator Fan Assembly and can be found in your local junk yard for cheap or at RockAuto for $287 (as of 12/15/23).

This is a 19”, 850 watt, brushless, PWM controlled fan that pulls air through the radiator, AC condenser, and grill of my ’67 bird like nothing I’ve ever seen before. There are some other models out there, like the 650 watt version for the C7(?) Corvette and I think that VW &/or Volvo has a dual fan setup, but this is the one I used.




The fan is 19” diameter, plus the frame, and the Firebird radiator has a 23”W x 16.85”H core so I had to do a bit of fabricating.
Fortunately, the frame was the perfect width to fit the 23” wide core although I did have to cut a couple of the protruding mounts off of the sides to clear the inlet/outlet.


I trimmed a piece of aluminum angle to fit the top to be a mounting bracket. (I polished this to a mirror shine later on.)


I installed some of this foam tape to prevent chafing and seal the fan frame to the radiator.




The motor adds about another inch, but it’s still and extremely low profile fan when compared to brushed fans.



Since the fan is so much taller than the radiator core, I added a plate to the bottom to seal thing up. It hangs down about 5”, but doesn’t interfere with anything and buts up to the back of the lower air baffle.
I think I had a piece of ½” square tube filling the gap between the radiator & fan frame, but a piece of angle would also get the job done.





This fan needs around 70 amps running at full speed so 8awg wire and a 90-100amp fuse is required. If you want to use the factory type plug, you can find it on Amazon for about $25. Search “GENUINE NEW Replacement Connectors, Terminals and Seals for Spal Kit 30130628 Brushless Fans”
A cheaper alternative would be to find one in a junk yard.


Since this is a brushless PWM fan, you will need a PWM controller. I went with the “Widget Man” BRUSHLESS PWM VARIABLE FAN CONTROL from eBay for $65. I had a few problems and the seller, “GKGoodCheapParts”, provided excellent customer service. The controller is small at about 1.25” square, but is easily programmed to come on at whatever temp you want and reach full speed when you want.



The problem that I had was that when I turned on my AC, it spiked the circuit, releasing the magic smoke in the PWM controller. The controller has a “Force On” terminal that will force the fan to run at full speed or will add 50% speed to whatever it’s currently running, depending on how you set it up. This terminal is normally grounded and when the ground is removed, the fan ramps up speed. If you’re not running AC, you could ground this terminal through a switch so when you threw the switch (opened the circuit) it would act as a manual override for the fan. If you are using AC, I recommend that you use a relay to lift the ground. …Just in case.

The first relay in the pic below creates a circuit that isolates the controller from the AC compressor, and any 12v+ source, and the second relay provides for a manual override to force the fan to full speed.



Here are a few different angle of the install. For reference, there was only about 5” between the radiator & water pump pulley.

[70GS455]

Wow. 70 amps current draw at steady state. It must really move some air. A rough rule of thumb for Spal and Derale fans, based on their published specs (which are most believable) is that the fan will move about 100 to 110 cfm per amp. So that's in the neighborhood of 7000 cfm, if that estimation holds.

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