SBC fan and thermostat question (1 Viewer)

[belaw]

I recently blew a head gasket on my SBC powered 40 and ultimately tracked the problem down to overheating. While I'm having the heads re-worked I want to address the problem, and
I've got a couple of questions I need help with.

First, how far should the fan be away from the radiator? I
16" fixed fan, with a 5" gap between the radiator and the face of the fan. Is this too much? Would closer be better? I would like to switch over to a clutch fan, which will move it a bit closer. It currently has a short water pump, but a long pump would move it an additional 1 3/8" closer

Also, what is the best thermostat rating for hot southern climates? The truck was originally from Colorado, but now its in south Louisiana, where it gets a good bit hotter in the summer.

Let me throw in that the fan shroud currently only goes 3/4 of around the fan; there's a gap from 3 o'clock to the 6 o'clock position. The first thing I plan to do is use some sheet metal to fully encircle the fan with shrouding.

 

[fieldsken1]

first of all you dont need to change the water pump just add a spacer to get it closer to the radiator. if you build a good fan shroud that makes a big differance. this fan works great.they also make an 18 inch fan. Flex-a-lite 1817 - Flex-a-lite 7-Blade Fans - Overview - SummitRacing.com hers the fan spacers they make them up to 3 inches.http://www.summitracing.com/parts/FLX-14556/

 

[chevurai]

SBC Cooling

I have fabricated several fan shrouds. A 60 series with a 383, fj40s with 350s and 2Fs. All had over heating problems that dissapeared with a properly made shroud. Coverage from the radiator to the outer edge of the fan blade should be continuous and as close to the tips of the fan blades as possible allowing for engine and frame flex. The distance from the fan to radiator is less important. Mecanical clutch fans are the way to go. Also the number of blades and their pitch have a great affect on air flow. I am currently working on a Fj 40 project with a 350 and it had a 3 blade (that went in the trash) and was replaced with a 5 blade. Some engines need a 7 blade. Check all the usual stuff, water pump working, antifreeze mix, thermostat operating , radiator not plugged, etc. Start cheap improve the shroud and try it.

 

[fieldsken1]

I have fabricated several fan shrouds. A 60 series with a 383, fj40s with 350s and 2Fs. All had over heating problems that dissapeared with a properly made shroud. Coverage from the radiator to the outer edge of the fan blade should be continuous and as close to the tips of the fan blades as possible allowing for engine and frame flex. The distance from the fan to radiator is less important. Mecanical clutch fans are the way to go. Also the number of blades and their pitch have a great affect on air flow. I am currently working on a Fj 40 project with a 350 and it had a 3 blade (that went in the trash) and was replaced with a 5 blade. Some engines need a 7 blade. Check all the usual stuff, water pump working, antifreeze mix, thermostat operating , radiator not plugged, etc. Start cheap improve the shroud and try it.

you say some need a 7 blade well why not use one to start with then you dont need to change later if it does need one

 

[chevurai]

The point is, start with what you have. It may not need a 7 blade. The existing fan may work fine. Make one change at a time. That way you will determine the weak area on your engine.

 

[belaw]

Thanks for all the advice. As I mentioned, I definately plan to start by filling in the gap in the shroud and replace the flex fan with a rigid fan and clutch.

Can anyone chime in on the best thermostat tempt rating for hot climates?