FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Tunnelport427 on February 09, 2026, 04:36:47 PM
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Wondering if anyone can help with info. I have a 67 Mustang with a Tunnelport 427, headers, cam, injection. It runs about 210 degrees, have seen a high of 219.
Electric 35 gph pump, spal 2024 puller fan, fabricated shroud, alloy radiator, (copy of the original copper one).
Running a thermostats makes it worse.
Fan is set to come on at 185 degrees.
I am scratching my head here, do I try a larger capacity water pump, larger radiator?
Any help appreciated.
Thanks
Rodney
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When the weather heats up, you might try running it with the hood off or at least 1" spacers at the hinges, to make sure there is enough air flowing threw it.
Then, the first thing I would do, is put as small a pulley on the water pump, to increase the flow.
The addition of the thermostat, increasing temp, maybe says there isn't enough flow for the "that" radiator but, the fins may be to many and or to thick, not letting enough air threw.
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Does it overheat at idle or cruising or both? What is timing, and can you increase it without detonation? Small water pump pulley is a good idea.
Pat
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Will check timing, but think it was 37 degrees all in. It runs hot at both idle and on the road. I am running a 35 gph electric water pump.
I went to an alloy radiator as it is the same size as the old copper one , but way more tubes.
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Years ago Meziere told me that my 650 HP FE needed a 55 gpm water pump to keep it cool on the street. If you are approaching that kind of power, I think you need a higher flowing pump. Also, a duplicate of the factory radiator in aluminum sounds like a weak spot to me, you could probably use a bigger crossflow.
A lot of people have trouble with the engine getting hot at idle, and then cooling down at speed. This is usually the factory water pump turning too slowly at idle. Conversely, it is also common to have decent cooling at idle but overheating going down the road; this is usually the radiator being too small, plugged up, etc.
I'm thinking that you may have both problems since you are seeing cooling issues under both conditions. However, bear in mind that even 220 degrees is not really that hot; as long as you are not spitting coolant out of the radiator, you probably aren't hurting anything.
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What distributor? Does it have vacuum advance?
If it's a street engine with moderate compression, and you have good gas, like 92/93 octane, those heads can safely go to 40-42* of timing. That would help. Before spending a bunch of money, I'd double check your timing, making sure your TDC mark is correct. Retarded timing will affect temps at all RPM levels.
I run 40* on my 427 MR in my Mach 1, 500hp, all factory iron, stock brass radiator, stock shroud with Edelbrock pump, and it's fine on the street. Though at prolonged idle it will start to creep on a hot day. If I don't mix some race gas, it will start to diesel on shutoff if it's a hot day, so I use the clutch to keep that from happening. If it's an automatic, you can shut if off in gear. If I mix some 110, it's not an issue.
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Setting up the distributor so it has less mechanical advance, allowing you to run more initial advance, will result in the engine running cooler at idle. Just part of the equation though because I agree with Jay's post about radiator size and condition.
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You are not crazy hot, just warm, when matters
Hot idling-- fan or timing, usually fan. I'd call fan volume the #1 issue I see in warm FEs
Hot driving -- usually radiator, exit airflow issue, pump flow or engine problem (or timing if advance very slow)
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If people don't think 220 is hot then what is hot in a street car?
Get the biggest radiator you can fit crossflow best and bigger pump like Jay said you could try lowering your fan starting temp too I would start at 160
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My cutoff would be about 230; over that and I'd be shutting it off to let it cool down. For what it's worth however, the engines will usually make more power running at a low temperature, because the intake charge won't heat up as much before it hits the cylinder. I personally like 160 degree thermostats, and keeping the engine at 180 degrees or lower in all conditions.
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On my car, with the tunnel port in it, would run temps under control with a factory big block copper/ brass rad, shroud, mechanical fan. If the rad got some trash, then it would have trouble. A good fan set up should have air movement that you can feel in front of the grill while at an idle. My first block had a rusty water jacket and if it was ever rattled, then it would shed rust and eventually plug the rad. Next one was squeaky clean and never had an issue. Water pump and fan speed is important. An electric fan would never cool my small block ranger but a mechanical flex fan would
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If people don't think 220 is hot then what is hot in a street car?
Get the biggest radiator you can fit crossflow best and bigger pump like Jay said you could try lowering your fan starting temp too I would start at 160
This people thinks 212 is boiling for water at sea level, with a 14 lb cap you are in the 240s, then add the antifreeze, even less likely to boil. However, I didn't say I like 220, it's getting pretty warm and depending on what you are doing with the car, you are getting close, but as I said, unless we knew when it was getting hot, hard to determine why and give advice.
That being said growing up in the Northeast, it was easy to cool a car, same 50% of the year in Nebraska now. However, almost every problem child I dealt with when living in Vegas with 150 degree pavement heat, was solved by airflow. A 2000 cfm single SPAL fan is better than most, but if he is heating up at idle, that's where I'd start
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I have tried many electric fan combinations over the years and they have always resulted in overheating. I think they need to be carefully matched (or fluked) to radiator fin/tube density. Nothing has come close to the big factory paddle fan and shroud.
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Thermostat makiing it worse might be the clue. Points toward Jay's comment about coolant flow - water pump.
is this a "new build" or something that has been running for a long time?
I have seen engines that got hot very quickly on dyno when head gasket was installed backwards.
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The distributor is Billet MSD, no vacum advance. I am running 98 octane which equivalent to your 93.
The TDC pointer is correct.
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I am running 98 octane which equivalent to your 93.
Where are you located Rodney?
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I am running 98 octane which equivalent to your 93.
Where are you located Rodney?
Your onto it 66FAIRLANE ;) Australia I hope?
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A laser thermometer can tell you a lot. You can get them for less than 20 bucks. That will help you understand whether the problem is on the cooling side, or the engine side. With that, you can look at the temperature deltas between the radiator inlet and the radiator outlet. A normal spread is around 10-15 degrees. A narrower delta, like less than 10 degrees, means you don't have sufficient cooling capacity which can be too small or inefficient of a radiator or inadequate airflow through the radiator from a faulty fan or drive assembly. A wider delta -like too cool- can point to restricted flow, meaning coolant is spending too much time in the radiator. You also want to check the whole surface of the radiator. You are looking for wide temperature variations that tell you where there are restrictions.
For the engine side temps, you want to look at what temperature you get at the water pump inlet and the manifold temperature ahead of the thermostat. The delta is very similar. Retarded timing or a lean mixture will give you a wider delta. Low block pressure can do that too as low block pressure can allow steam pockets to form and once you have steam pockets, you aren't cooling that piece of metal. You get low block pressure from a slow or inefficient water pump. Also, don't run straight water of any kind. Water has high surface tension and the electrons don't like to get friendly with metal components so you get poor surface contact. Use antifreeze or a surfactant to break the surface tension.