Thread: cooling my 36 chevrolet..

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Posting everywhere to get help.. I have a 36 chevrolet sedan with good upgraded radiator and 350 stock small block and auto tranny. The engine sets quite low in the bay and the small engine fan only covers part of the lower half of the radiator. The car seems to cool quite well moving down the road but overheats at idle. The original owner installed a straight fan shroud that fits snug to the radiator and extends about 2" or so past the fan toward the engine so the fan is completely enclosed in the shroud. I read somewhere that the fan should be partially out of the shroud? Does this make substantial difference in the air flow? What other suggestions for cooling this little rod? I think I might be able to fit a 14" puller if I remove the engine fan,, would that move substantially more air? Any help appreciated.

Welcome to the family and although I can't help you personally, I'm sure somebody will jump in soon with questions and idea's to help. Pictures are also recommended as it helps people to visualize the problem. Welcome anyway..

Since it cools quite well moving and heats up when in traffic or stopped That's a clear indication of an airflow problem.
You say the engine sets low in the chassis and you only have half a fan pulling air... I'd say there's your problem.

I think you've got two choices. Either go with electric fan(s) to cover as much of the core as possible. OR, find one of those raised water pumps and that will allow you to engage more of your current fan.

I prefer choice number 1.

I don't like electric fans, so I'd cobble up a mechanical fan fix, maybe something like this....
http://www.snowwhiteltd.com/PDF/RiserWP.pdf

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I don't think the fan is working well since it is completely enclosed. First before spending money, I would cut the shroud so that it is halfway on the width of the fan blades. Fan should be half in - half out. This gives the air better flow. Give it a shot. If it does not do enough for you, then go with the riser fan locater as tech suggested. Even with the fan higher, it will still work best with a shroud moved to match. So, you have not lost anything by doing the cut.

I'm not clear what you have. Does the shroud cover the entire core of the radiator, top to bottom, side to side? Is the opening in the shroud a little larger than the fan diameter? What diameter is the fan on your engine? Without that information or a photo I don't know how anyone could recommend a solution. (No offense to you guys who offered information above)

I have THIS FAN & SHROUD on a 430 HP small block, and it runs dead on 180 all the time in Texas weather.

Without a picture it's harder to speculate, but it certainly sounds as if a modifying the fan shroud is the first step. You see, a lot of airflow is created from centrifugal effect: as air slings out from the fan blade ends. Having the fan fully enclosed , you loose that air flow.. that is why the fan should be "half out", as you said.

Originally Posted by 34_40

I think you've got two choices. Either go with electric fan(s) to cover as much of the core as possible. OR, find one of those raised water pumps and that will allow you to engage more of your current fan.

I prefer choice number 1.

Agree. From personal experience, I found that a fan should be centered in the radiator. If it is too low, then it will not cool well. An electric fan is you best solution. A lot of us run them with no problems. SPAL is generally considered the best. I run a 16 inch in my '32, and it cools quite well.

I'll add to what the guys have said above just to give more info, nothing they've said is "wrong", but there are multiple solutions. Since you've admitted to seeking answers "all over the place" you're going to get some that are less effective, but since you're asking you may not know which is which.

To me, the least desirable choice/selection is/are fan(s) mounted to the front as an auxiliary. In the wide range of operating conditions they'll block more air than they provide. "More is better" is a false promise, one fan properly set up on a properly tuned engine will get the job done.

Yes, your fan is too far into the shroud, it's pushing the air coming off the fan blade tips and edges back around inside the shroud causing air to jam up rather than exit. High speed ram effect helps clear that which is why you don't have problems at freeway speeds. As mentioned, have the blade sticking halfway out the shroud opening. Folks have mentioned shortening your existing shroud, and I would add; or shorten the spacer between the pump flange and the fan blades if there is one.

The height of the fan to the radiator core ideally should be higher, but a properly fitted shroud will make up for much of that. To add to Richard's suggestion of the Snow White pump I'll mention that a company called Zip's makes one as well that is very similar, though I prefer the Zip's because it uses a more common pump, easier to find for replacement (unless Snow White has changed from the Opel one they used to fit). In the electric world the one that Jack posted is very good because of the fitment to the entire core, and can be good in some tight fitment circumstances.

Here's a link to a picture of a proper setup of a tall, narrow radiator, with a properly made shroud and an electric fan. The shroud covers the entire back of the radiator. If possible, use a 16" diameter fan, from a reputable company like SPAL. http://www.prchotrod.com/media-cente...m_radiator.jpg

There is a good reason to use an electric fan instead of mechanical - you get more air flow when idling in traffic and the fans shuts off when not needed, so there's no loss of power at cruising speeds. All modern cars use them, AFAIK.

It was brought up recently that some companies advertise large flow rates for their fans, but that's probably at zero pressure drop. Any good company will publish the air flow rate from zero pressure drop, on up to the maximum pressure drop, where air flow is reduced to zero. This link should take you to spec for the fan that's on my car. It does the job, but I'd like something quieter. Notice that the pressure drop in in millimeters of water, not inches and flow rate is also in metric units. The conversions are at the bottom of the chart. For example, this fan flows 1156 cfm at .4" pressure drop and a maximum of 1600 cfm.

https://webstore.spalusa.com/content...01517_SPEC.pdf

This 14" fan will flow a similar amount of air.

https://webstore.spalusa.com/content..._2056_SPEC.pdf

I'll probably be switching from my 16" SPAL straight blade to this higher performance model:

https://webstore.spalusa.com/en-us/p...-16-c-12v.aspx

Here's a Maradyne, with a proper graph of the flow.

http://www.maradynehp.com/m162k.html