JMD

Jim is using a northern brand (Summit brand) radiator on his aluminum head 408.

It is installed in his 66, and it is a direct bolt in. I don't think this radiator offers a lot of extra capacity, but it is sufficient.

These are available on the Summit website for about $300.

I would be interested to know how many rows are in your radiator, I could see a 2 row being marginal, but a well sized brass/copper 3 row should be doing the job for you. The radiator I mentioned above is a 2 row aluminum, which should cool better than a 3 row copper/brass of comparable size.

Also, make sure you are not running lean, (with your changes) this can cause an overheat condition as well.

scootchu

Has anyone said "water pump"? You had a new one put on. is it rotating the way it is designed to?

67t5ponycoupe

I would not worry about the radiator until the other items are corrected. You said it cooled ok before and the aluminum heads should not make it run any hotter.

PReal

Which Bumbera's are you going to? Katy or the original location on highway 6?

I have heard nothing but positive reviews about Bumbera's and would have a hard time thinking they were trying to cheat you.

As a fellow Houston guy.... how hot is the car getting? Where/How are you taking your temp measurement? Is it physically overheating.

My car has a new 3 row radiator and it still gets close to 230 on my aftermarket mechanical temp gauge mounted to the intake. With how hot and humid it has been of late it has been really hard on my car to stay cool. I might even consider some water wetter just to keep the temp a little lower.

Do you have a fan shroud?

JMD

Not exactly true, aluminum combustion chambers will positively dump more heat into a cooling system than their iron counterparts.

This can be clearly demonstrated when trying to weld aluminum, it takes a significantly higher heat setting to make a weld because the aluminum is so much more efficient at moving heat than either iron or steel.

This concept is further demonstrated in the fact that as a rule of thumb, aluminum heads allow a full point higher compression ratio than their iron counterparts, this is virtually solely due to it's ability to transfer heat faster than iron.

The addition of aluminum heads may not make a huge difference in a vehicles propensity to overheat, but they could in fact push a marginal system over the edge. Consider that there are plenty of Mustangs out there that don't have enough "reserve cooling" to handle an additional 5 or 10% more heat in the cooling system.

Also it is important to define just what constitutes "overheating", it means different things to different folks, but in general, I consider a vehicle to be overheating when it pukes antifreeze.

2+2GT

Ford considered 220° to be the point of overheating, which is where the DVCV in later cars kicks in to cool the engine.

67t5ponycoupe

Edlebrock told him that it will not run hotter with a properly installed set of their heads. You can talk all the theory you want but the bottom line is the car should not be running hotter. The two major factors for it running hotter, in my opinion are the failure to drill the hole in the block and not installing a thermostat. I question the mechanics knowledge and ability since me made those two mistakes. You have to run a thermostat to allow the system to be able to hold water in the radiator long enought to cool it down.

JMD

Put bluntly,,,, Theory and fact should not be confused... and semantics must be considered.

Edelbrock is right in that an engine with aluminum heads should not run hotter than an engine with cast iron heads, but only so long as the cooling system has the capacity to deal with the extra heat it has to contend with. (and the cooling system of an aluminum headed engine WILL have to deal with more heat than it's iron headed counterpart.)

Mustangs have a well deserved reputation for not cooling very well for a reason. The size of the radiator opening alone lends itself to marginality.

Am I saying that the problem is absolutely with the radiator? No, I am saying that this issue needs to be considered before fingers are pointed at the engine builder. (although the lack of steam holes could be the issue)

I agree that the thermostat should be installed for the sake of elimination of this as an issue, but I also contend that it is way out of line to automatically assume that the engine builder is at fault for this problem. It is way too easy to assume, check my first post on this thread, I think I jumped the gun on the first post myself. Assumption is not a replacement for sound measured reasoning, nor should assumption impose a hurdle to reason.

Edit-- Deleted comments not applicable due to differences in early 289 and 351 engines

JMD

I have a theory on this that I formulated when trying to figure out why a 1970 SBC is considered to be in an overheat situation at say 220*, and essentially the same SBC made in 1995 is not considered to be in an overheat situation until about 260* (I didn't research these figures, just off the top of my head, but they will work for the sake of demonstration).

What is the difference between 1970 and 1995? Without going into detail of the "hows" and "whys", to make a long story short, I have concluded that the temperature of the coolant does not effect whether an engine is in an overheat condition so much as to whether the coolant is boiling in the engine thereby creating imperilment to proper flow, and insulation of the combustion chamber from heat transfer.

Steam is the BIG enemy when considering the inability of liquid to transfer heat from point A to point B much more than the temperature of the coolant itself. (A radiator will actually become more efficient at dissipating heat as the coolant increases in temperature)....

In my way of thinking, STEAM is the enemy, and as such steam is an indication of a true overheat condition, within reasonable bounds of course.

My conclusion was that it is certainly possible to "cheat" the old overheat standards by incorporating some modern cooling system features to to old cars.

2+2GT

In an engine with a cooling system pressurized to, say, 14 psi, you won't have any steam below about 250°.

I would put a real Ford 190° thermostat in and see what happens. It'll take under an hour and cost about $10. Modifying the cylinder block will take a whole day, and cost at least a valve job gasket set.

My 1997 SBF stays nailed at 190-200°. I'm pretty sure 260° would be completely off the top end of the gauge.