6 cyl flat head cooling fan

I just finished rebuilding a 49 Plymouth, has the flat head engine. I've noticed running around 55-60 the engine sounds like its turning to high rpm's. the gent I bought it from came by to take a look and he pointed out that he had replaced the stock fan with the 5 blade thats on it now. after he left it hit me, could this be the reason it sounds like its turning to high. the stock fan is a odd looking 4 blade, I say odd because the blades are not opposite each other but have a slant look to them. could this change in fans be causing this or is it I'm not use to hearing a flat head 6 running 55--60mph on the highway--------thanks, Richie

Yes, it could be the fan. That funny looking one with the blades staggered is made like that so it doesn't set up a frequency of vibration, which is what makes noise.

Any chance that five blade fan is one of those Flex Fans with what looks like stainless steel flexible blades? If so , they are quite noisy at higher RPM's

Its a steel fan, didn't think to ask the guy what it came off of. last night I found a stock fan on ebay and I'm going to bid the last 30 seconds and hope to get it-------Richie

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Originally Posted by Richie

Its a steel fan, didn't think to ask the guy what it came off of. last night I found a stock fan on ebay and I'm going to bid the last 30 seconds and hope to get it-------Richie

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Falcon/ Mustang 6cyl fans are staggard/ small, and use a standard bolt pattern, 1 of them might work, if you loose the bid on the stocker. they don't make too much noise.

Pull off the fan and go for a quick ride at those speeds to see if it goes away. A buddy of mine had a '49 Plymouth (stock) and it didn't like to go that fast without making some noises, as I remember.

But pulling the fan off will be the proof.

Don

Those flex fans aren't generally worth a damn. While they can, repeat, can add miniscule HP they do not cool throughout the entire operating range of the engine as well as the original fan. There's a reason the stock fans work- they were engineered to depending on their specific application. Aftermarket one-size-fits-all for anything is a guess at best.

If anyone really, really needs suplemental cooling best to get an electric- yeah they make 6v.

those flex fans do really suck! i have a fan if you need one plus a few other flattie parts...let me know

well i must be odd man out again ive got a flex fan and it sure works!

i guess i should say they suck in my 49,sorry gasser

I bought a stock fan for this flat head and it made a lot of difference in the noise and seems to run better, now I'm taking a 1940 Packard apart. just about redy to pull the body off the frame, it will come off today, just a few more bolts. this will be a street rod, at 66 I feel like a kid in a candy store. having to much fun----------Richie

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Originally Posted by gassersrule_196

well i must be odd man out again ive got a flex fan and it sure works!

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Agreed, never had a problem with them.

Anybody need a 6 blade fan and pully I'll take 25 for it and you pay shipping, its the one i HAD ON MY 49 Plymouth-----------Richie

you got any of the trim peices?

Sorry, all I have is one nice looking 49 Plymouth---------Richie

thats cool i hope to say the same soon

The problem with aftermarket "one size fits all" is that it is a hit and miss situation. Sure some vehicles may take the fan and operate fine and others will not. We gotta stop and think why engineers actually bother to calculate things for the vehicles or engines they are designing. If any fan was every fan in 1949 there would be no difference from Lincoln to Kaiser. But there is because engineers caluclated pitch, blade number and blade length, tip sweep and weight. They made them for effeciency in producing the best cooling at all RPM, low noise and using as little HP as possible.

I can tell you for sure a fan that does all of that for a 230CID 49 Plymouth 6ain't gonna do the trick on a 359CID straight eight flathead Packard or a 331 Cadillac V-8!

What goes for a 65 Chevelle with a built 396 has nothing to do with a stock 49 Plymouth which ain't a hot rod in any sense. It's a vintage car.

How can anyone tell their flex fan works short of a dyno session? If it don't overheat it's working we guess. Well if it's a big deal is it running cooler than before? Can you tell if it is quieter and does that even matter on the mill you're running? And the big advertised payoff- how much extra HP is it producing? Could it be as much as 3HP? Is that noticible even on the dyno? Anybody that believes statements like "10 HP increase" or "10% better fuel economy" has to realize that any performance increase would certainly vary relative to the application. Don't believe the stuff that comes from sources that tell you magnets inprove gas mileage or spinning dealies in your aircleaner give more HP. It's ludicrious.

Well said TWICH. I think the only cooling improvement over the stock fan is an electric and if that doesn't do it then add a full radiator shroud to it.