Looking for 351 Cooling Improvements.

Randyi00 said:

I'm looking to make some improvements in my cooling system. Generally speaking, it runs cool enough under most driving conditions. Only when I'm idling in traffic in the summertime, it starts to rise north of 190-200C. For context, it's a 393 build, nothing super crazy. Cooling system is pretty much stock aside from a lightly upgraded OEM style radiator with 1 or 2 added cores.
So my question is, where is my money best spent to get it to run a bit cooler? Higher flow aftermarket water pump? Aluminum radiator? Electric fans? I'm not looking to go all out and spend a bunch of money, I just need it to maintain a reasonable temp when I'm stuck idling at a light or in traffic.

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Cleveland Crush said:

My opinion Randy...if you have a mildly built engine and it runs around 200 degrees in traffic you have absolutely nothing to fix. Enjoy your Stang, sounds like it's running great!

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detritusmaximus said:

Assuming you have a good fan shroud and fan clutch?

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72conv said:

I agree with Cleveland Crush. Water Wetter would help, and if you live in an area where it doesn't get below 0 deg F, run 30% antifreeze and 70% water. That combination is good down to 0 deg F and raises the boiling point by about 30 degrees. Try the simple things first before you spend a lot of money on hardware changes.

If you do need more, a 4-row radiator makes a big difference, and if it's done right, even a concours judge wouldn't spot it. I had mine done that way when the original rad started seeping at one of the seams. The shop used my original tanks and top and bottom straps and a 4-row core that is the same thickness as the original 2-row core, so the modified rad shows the correct part number and date codes. An aluminum rad will really cool, but you're getting into much bigger bucks and possible modifications to the car to accept the new rad.

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Spike Morelli said:

O.K., this may or may not be applicable to what you're experiencing, but here's food for thought. Years ago, I had a '70 442 W-30 Olds with a 455. Cooled fine as stock. then, I pulled the engine and had Joe Mondello ( for those younger guys and girls out there, he was THE Olds engine guy ), do all my machine work and supply the parts, along with fully ported/ polished heads. The thing was a street monster, but.....ran hotter. I put a 160 t-stat and heavy duty flex fan on. The car had A/C, so it already came with a H.D. radiator with max cooling. I yanked the radiator while building the engine and had the radiator shop clean and "rod" it out, so it was clean to begin with after installing the new engine, but temp guage showed increased temps. I had the radiator shop re-do the same radiator twice more searching for a cure. Finally, I went to another radiator shop with run by an older gentleman who'd seen most everything come thru his doors. He immediately recommended a higher fin count, denser core. As it so happened, a Chevy truck core was the same dimensions as my Olds, so it was a simple job of soldering my tanks and side straps to the new core. I'm telling you, that radiator cooled so well, that I put the 180 t-stat back in, switched back to the stock fan just so my heater/ defrosters would work. Of course, the engine now could stay happy even with a boat on the hitch and pulling through the desert at noon. The beauty of the brass radiators is just that, they're rebuildable and customizable, aluminum ones are not rebuildable. More rows of tubes are one thing, but you can't beat a denser fin count radiator. It's how old hot rods keep their cool as well, with those smaller down-flow radiators........they use denser fin count cores.

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giantpune said:

I'm also going with the hive, leaning towards something may be wrong. I'm down here in GA with 100F summers. With a built 351 and stock fan, radiator, water pump, and shroud, I can idle all day in traffic and not overheat. I'm just using the cheap autozone pre-mixed 50/50 coolant.

Your 393 should only be putting out like 2HP while its idling. The cooling setup can keep up with that.

I'd double check the basics before you throw parts at it. Fan spaced correctly in reference to the shroud. Correct style thermostat for a cleveland. Sending unit and gauge are reading accurate temperature. Water pump is pumping a decent amount.

And to echo what @Spike Morelli said, look at your radiator core and see how closely the fins are packed in. Not all aftermarket ones are created equal. You may have bought something that says "5 cores", but they do not indicate the fit count. Thats the difference between a good radiator and crappy ebay special from china.

I don't think an aftermarket water pump would fix the issue, unless the one you have is just underperforming.

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Randyi00 said:

You mentioned the thermostat and that made me think........ Probably 10 or 12 years ago I recall replacing the thermostat and at the time I don't think I was thinking about the factory restrictor plate. I couldn't recall now what I had put in there but I just pulled it out and sure enough it's a windsor style, still with the restrictor plate in place. That could very well be my problem.

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Randyi00 said:

What's everybody take on a proper 351C thermostat with an OEM restrictor plate vs a new style aluminum block off plate and a regular ford small block thermostat?

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Randyi00 said:

What's everybody take on a proper 351C thermostat with an OEM restrictor plate vs a new style aluminum block off plate and a regular ford small block thermostat?

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