Educate me on why 340 fan is not symmetrical

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inertia said:
Timing marks, timing cover, pulley depths, lower rad hose, power steering pump brackets, location are all diff between cast iron/alum water pump.
Just so you know.
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Thanks. Was aware of timing marks and timing cover. That is why I initially stayed with 70's hardware. I do not have power steering. The timing was told is not a deal breaker. Can have the radiator modified but can't do that to a year only radiator. Boils down to pulleys.
 
RustyRatRod said:
Three reasons. It moves more air, it's quieter doing it and there's less drag than a symmetrical fan because of how it breaks the air up. The MP engine book has covered all this in good detail for close to fifty years. The problem there is also three fold. First, people refuse to believe what they read. Secondly, people won't read what you tell them. Lastly, now, unfortunately, the MP engine book is getting difficult to find copies of. I think the last printing was the ninth edition for both the engine and suspension manuals. I used to preach those manuals hot and heavy around here, but I just gave up for the three reasons mentioned above. Especially the first reason. People just will not believe the information in those manuals. They'll argue every step of the way the information is "wrong" as if they somehow know more than all of the racers and engineers whose vast knowledge spans well over 100 years collectively.
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Would tend to agree with you. I may be guilty on this issue. Hard for me to believe they would build a fan like that but who am I to argue with engineers much smarter than me. I felt the need to understand the whys about it due to it being such and obscure design for me.
 
RustyRatRod said:
Three reasons. It moves more air, it's quieter doing it and there's less drag than a symmetrical fan because of how it breaks the air up. The MP engine book has covered all this in good detail for close to fifty years. The problem there is also three fold. First, people refuse to believe what they read. Secondly, people won't read what you tell them. Lastly, now, unfortunately, the MP engine book is getting difficult to find copies of. I think the last printing was the ninth edition for both the engine and suspension manuals. I used to preach those manuals hot and heavy around here, but I just gave up for the three reasons mentioned above. Especially the first reason. People just will not believe the information in those manuals. They'll argue every step of the way the information is "wrong" as if they somehow know more than all of the racers and engineers whose vast knowledge spans well over 100 years collectively.
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Those MP books are the real deal. A veritable Goldmine of info.....wish I still had mine
 
pishta said:
noise reduction comes to mind. The even spaced "chopper" blades create a frequency (google chrysler air-raid siren) and if you can break that frequency up (different blade spacing) you can reduce the drone. To think Chrysler developed this minute feature and ignored UTG's slant six "oil sloshing problem on rear rod bearings"? C'mon man!
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"Uncle Tony" pssshhhhh... the dudes been going downhill lately IMO. I mean he's always been full of it, but its getting worse. He should have planned better in life I think.
 
RustyRatRod said:
Three reasons. It moves more air, it's quieter doing it and there's less drag than a symmetrical fan because of how it breaks the air up. The MP engine book has covered all this in good detail for close to fifty years. The problem there is also three fold. First, people refuse to believe what they read. Secondly, people won't read what you tell them. Lastly, now, unfortunately, the MP engine book is getting difficult to find copies of. I think the last printing was the ninth edition for both the engine and suspension manuals. I used to preach those manuals hot and heavy around here, but I just gave up for the three reasons mentioned above. Especially the first reason. People just will not believe the information in those manuals. They'll argue every step of the way the information is "wrong" as if they somehow know more than all of the racers and engineers whose vast knowledge spans well over 100 years collectively.
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No offense to anyone here, but I just had this conversation with the wife, it was about porting and hogging out 318 heads. I said "they'll never make them into 340 heads, its a different casting...people waste their time when they can just buy a set of heads, I don't get it. No grown man is that broke if they are building a Mopar, and these guys think they know something Chrysler engineers didnt..." I just get frustrated at the stupide' things I see ion the internet sometimes with cars. Its to the point where say you can afford a nice car, you still have to tear it down and make sure the guy before did it right.
 
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Ironracer said:
Those MP books are the real deal. A veritable Goldmine of info.....wish I still had mine
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Although not updated in a long time, all of the information is still relevant and correct.
 
Dartswinger70 said:
No offense to anyone here, but I just had this conversation with the wife, it was about porting and hogging out 318 heads. I said "they'll never make them into 340 heads, its a different casting...people waste their time when they can just buy a set of heads, I don't get it. No grown man is that broke if they are building a Mopar, and these guys think they know something Chrysler engineers didnt..." I just get frustrated at the stupide' things I see ion the internet sometimes with cars. Its to the point where say you can afford a nice car, you still have to tear it down and make sure the guy before did it right.
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"No grown man is that broke if they are building a Mopar" But I'm getting there quick.
 
jawbone said:
"No grown man is that broke if they are building a Mopar" But I'm getting there quick.
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I hear ya .what's funny is in the 80s they were cheap no one wanted them, now they are gold if you have the right one.

But another thing is, and this is speaking for myself, whenever i try and do something on the cheap or to save a few bucks I end up going back and doing it the way I should have to begin with, so I spent the money anyway sometimes even more . I get to where I just spend the money and don't even think about it these cars have to be done right or it just isn't the same, and I am a stickler for interior. Any car I own has to have interior, and everything in the dash has to work, its a peeve of mine . I cant stand a car with no carpet or door panels etc. unless its a drag car. Thing is its a Mopar, and when they are running strong and looking good, they are hard to beat.
 
ir3333 said:
...are you guys talking about Larry Shepherds Mopar books?
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I'm not. I'm talking about the Mopar Performance manuals.....though Larry Shepard had a hand in writing them.
 
jawbone said:
Why is it on some radiator fans the blades are symmetrically spaced and some are not
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Have a look at the tread pattern on your tires. They are not symmetrical either. It, as I understand it, is a noise suppression technique. Like white noise generators.
 
Radial aircraft engines are non symmetrical so they don’t shake apart and they are low rpm engines. Also machine shop reamers are non symmetrical as well so they don’t chatter when cutting.
 
ch1ll said:
Radial aircraft engines are non symmetrical so they don’t shake apart and they are low rpm engines. Also machine shop reamers are non symmetrical as well so they don’t chatter when cutting.
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May be a reason none of the woodwork in my house is square.
 
I have bolts in my Hayden #2947. Stock pre '70 radiator, cast iron pump.
 
I had an old 7 blade non Clutch fan. It sounds like a Cessna 172 taking off.

Replaced it with the 5 offset blade clutch unit and while not whisper quiet it is so much better. Its been on for 100,000 miles now and has not ventilated my hood, YET. I did replace the clutch unit once.
 
jawbone said:
Why is it on some radiator fans the blades are symmetrically spaced and some are not. In the process of purchasing fan for my 340 but am reluctant due to the blade orientation. It's a 340 fan with 2 1/4 pitch part number 2863 215. My research indicates this is for a 340, Mine is a 70 model engine going into a 68 Barracuda. Any help would be appreciated.
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Noise harmonics. Many 4 blade are two blade overlaid. To quiet them they are usually not at 90°. 5 blade have 3 kind of evenly spaced on one side and two closer together on the other side. This provides dynamic balance and breaks up the air pulses of the blades making it quieter.
 
TrailBeast said:
The fan blades are spaced such that the center of mass is placed exactly on the fan axis to minimize fan vibration. The resulting fan noise is 11 dBA quieter in discrete noise level than the even bladed fan system.
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Impressive. I am impressed.
 
CRUZE 418 said:
I have bolts in my Hayden #2947. Stock pre '70 radiator, cast iron pump.
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Been wanting to ask you but you already answered. You were able to use bolts in lieu of studs for mounting fan clutch. How much room do you have fan to radiator? Are you using a fan shroud?
 
When I put the 78 318 in my 65 Barracuda with a 3 core radiator I had to put the shroud over the water pump, put the pullys and fan on then slide the raadiator in place and fasten the shroud to it. No room to insert the bolts in the fan and get a wrench in.
 
Dave_J said:
When I put the 78 318 in my 65 Barracuda with a 3 core radiator I had to put the shroud over the water pump, put the pullys and fan on then slide the raadiator in place and fasten the shroud to it. No room to insert the bolts in the fan and get a wrench in.
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I here it's a difficult task especially with bolts and like you said, still have to wrench them on.
 
There is room for bolts, I have this #2947 on both of my cars. You have to have the correct length bolts, you have to finesse them in , use a pencil magnet or your neighbors dog, but patience and doing whatever it takes is how you get them in.
Yes, the fan shroud gets hung over the water pump, then install the clutch and fan, belt or belts then the radiator . Blow picture up to see bolts.

20220317_174130.jpg
 
as easy as the rad is to RnR I don't see a problem doing that; I mean you don't even have to remove the easily accessible bolts. Beats the heck out of skinned knuckles, and one-flat-at-a-time wrenching..
 
jawbone said:
I intend to use a clutch with this application. Noticed the 213 is a 1.5 inch pitch for the 340 and 383 specifically for Barracuda and Dart. Though I want the correct fan for the Barracuda, thanks for your comment regarding fan clutch. Really would like to use one.
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Then don’t look at the Mopar Performance 5 blade fan. It will really throw u 4 a loop. Kim
 
CRUZE 418 said:
You have to have the correct length bolts
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CRUZE 418 said:
I have this #2947
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Exactly. :thumbsup:

Never bad to dig up old threads with good info that might help others.
With the short clutch I will add that along with having the correct length bolts (I use the oem Belleville washers as well) it helped me by starting one bolt, turned in about a full thread. Then slip the fan assembly (clutch hub) over the pump pilot while at the same time slipping the hub bolt slot under that one bolt. Give the bolt a few turns till almost tight, it will hold the assembly in place so you can get the other bolts in. Use a good fitting open end wrench to tighten up. It’s not that hard actually.
 
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