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Post Info TOPIC: Big Block Electric fan contemplation


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Big Block Electric fan contemplation


I am just researching electric fan possibilities on a big block.  My 396 runs nice and cool (185) on the highway but slowing down in traffic, the temp gauge will climb up to 200.  With an idiot light, out of sight, out of mind and you really don't know what the temp of your engine is until its too late.  But with a mechanical temp gauge, you see the temperature moving up which creates anxiety.

Currently, I have a stock 5 blade fan 17 inch and a fan shroud.  I believe this would be stock on a Non AC car.  Please correct me if I am wrong.  This car had an after market GM air conditioner added at some point so the engine is pulling air through the air condenser first, then into the rad.  When you turn on the air in traffic, up the temp goes.  The rad is a new aluminum 2 row Champion, 180 hi flow T stat and a stock water pump.

So, I have a few questions, since it is an AC car now, did the AC version come with a 7 blade fan?  I wonder if more blades would do the job a bit better than the 5 blade sitting at red lights with the air on? Does anyone have a part # on a AC car mechanical fan? 

Secondly, I see some posts on here discussing Neon fan assemblies and talk about the Windstar fan assembly which are non GM obviously but can be altered in an economical fashion.  Champion also has shrouds and fans but they add up in cost and I am not sure about the CFM's required for a big block.

So, I am just looking for any input on perhaps using a different mechanical fan and just wondering if anyone has got really creative in adding an electric version that cool the BBC economically.   

Jake   



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I am wondering if you have enough radiator. I'm no numbers matching guy but I do like keeping these old bombs period correct so I was never one for an electric fan or new radiator. 

When I swapped out the small block in my car for the 454, the engine never overheated but I would see 200 to 240 on my gauge using that original two core which like you was a worry for me. 

I solved the problem with two changes:

1)   7 blade GM clutch fan that was a swap meet purchase (see photo)

2)   Re-cored radiator to a high efficiency 3 core which has greater efficiency than a traditional 4 core. (see photo) 

IMG_0908.JPG

IMG_0903.JPG

 



-- Edited by 73SC on Wednesday 6th of June 2018 11:27:43 AM

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Ray White, Toronto ON

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Jake, the parts book lists a 5 blade fan for factory air on your car, so that sounds like you have the correct fan.

How is the clutch? Is it tight, as in do you ever hear the fan "roar" on either cold start or when it starts to get on the warm side?

How many miles on the new engine? It's not impossible that it just needs to loosen up a bit.

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Carl Stevenson wrote:

Jake, the parts book lists a 5 blade fan for factory air on your car, so that sounds like you have the correct fan.

How is the clutch? Is it tight, as in do you ever hear the fan "roar" on either cold start or when it starts to get on the warm side?

How many miles on the new engine? It's not impossible that it just needs to loosen up a bit.


It is good to know that the 5 blade was factory for an 68 AC car, but there is no clutch on this one.  Just driven straight on the pulley on the pump with a spacer and is shrouded as I mentioned. 

Is there a roar?  I would say so as I grew up with 3 ton farm trucks that had 366's and monster rads and humongous fans.  They roared like a jet engine in low gear when you were crawling out a field with a load of grain.  This would not be the same roar in decibels but I think it roars.  I would say it sounds louder when warm but not entirely sure.  I know it is a bit of blasphemy with aluminum rads and electric fans, but I hate the roar of the fan.  I hear grain truck when I hear roar.  But, I do appreciate input from 73SC and anyone for that matter as we all have differences that floats one's boat.

There is about maybe 260 miles on the rebuild and runs very nicely.  I have the original 2 row Harrison rad and original Harrison heater core but I didn't have the funds to do a re-core at the time so I purchased a Champion rad, which seemed to have favourable reviews and some members on here were cooling BBC with them and it was economical at the time.  It is kind of a big ugly thing and I see the one you purchased for the Strato actually has a similar look to an original but I didn't stumble onto that till after you posted about it.  I also have all the original parts so that one day, everything could essentially go back to factory.   

Anyways, so it looks like I have a stock 5 blade fan, without a clutch, and a GM fan like 73SC posted would surely have to pull more air through the rad at an idle, one would think.  This engine hasn't went over 200 yet, and I might be a bit sensitive with this temp gauge but I would like 185 - 190 all the time, not just at highway speeds.  The 7 blade with a clutch looks like a potential solution. 



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Not sure why you're concerned about temp climbing to 200 F. I'd be happier than heck if mine only went that high.

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Strictly my opinion with nothing to back it up (!) but I would not be anxious to change anything yet with so few miles. 200 is not excessive. It's even possible your temp gauge has a 5% margin of error and the temp is closer to 190, who knows.

For the record, years ago my 427 4 speed car ran 215-220 in traffic on hot days. I didn't like it but it never over heated and never had an issue, it just ran hotter than I would have liked.



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Just a thought, have you checked the temp with an heat gun?

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Carl Stevenson wrote:

Strictly my opinion with nothing to back it up (!) but I would not be anxious to change anything yet with so few miles. 200 is not excessive. It's even possible your temp gauge has a 5% margin of error and the temp is closer to 190, who knows.

For the record, years ago my 427 4 speed car ran 215-220 in traffic on hot days. I didn't like it but it never over heated and never had an issue, it just ran hotter than I would have liked.


Good to know that these temps can go into the 215 range without overheating and I admit that I might a bit jumpy or sensitive on the temp.  I have not tried a heat gun to check actual temp either at this point.  But before the re-build, there is just an idiot light which never came on.  Then when the builder did the engine, he would not fire the engine up for cam brake in unless there was a temp gauge and an oil pressure gauge.  So now, there is a temp gauge and an oil pressure gauge that I never had before and you see temp climbing up in traffic and you start to wonder is it going to stop at 200 or keep climbing?  Hence, a bit of nervousness.

Interesting that the factory manual calls for a 195 T Stat.  The builder said put a 180 in it so I did just that.     



-- Edited by 68 Grande on Wednesday 6th of June 2018 03:26:19 PM

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If I remember right the red light comes on around 248!

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Carl Stevenson wrote:

If I remember right the red light comes on around 248!


248??  Wow!  By that time, your rings are likely toast and she is an oil burner after that.  248, Yikes!!



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The heat gun has many more uses. You can check brake rotor temp, ac temps and the heat inside the car with the windows closed.... Use it to check the temp of your exhaust at the tail pipe.... Check the temp of the brake fluid in the master....

Brake rotor or drum temps can be good for diagnosing out of adjustment problems.
Very cheap at Princess Auto.

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Heck the limp home mode in my Northstar kicks in at 262, fans come on at 224,. normal is around 205 to 215 but with these old iron blocks we get freaked easily. A Big Block generates a lot of heat. I see on Corvette forum guys are routinely running at 230, normal they say is 200 to 215.

 



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1973 LeMans 454 "Astro-Jet"

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73SC wrote:

Heck the limp home mode in my Northstar kicks in at 262, fans come on at 224,. normal is around 205 to 215 but with these old iron blocks we get freaked easily. A Big Block generates a lot of heat. I see on Corvette forum guys are routinely running at 230, normal they say is 200 to 215.

 


 

Thanks for the feedback on temperature and it appears that 200 is more of a normal temp for the BBC. I always wondered what the idiot light temperature sensor was triggered at so that was a good piece of info. And, admittedly, I do get freaked as we ran 366's in our 3 ton grain trucks and we overheated them on occasion as well as over heating 350's in the pickups.  That usually resulted in toasting your rings and then becoming an oil burner and needing a ring job.

But I do like that 7 blade or 6 blade fan and clutch upgrade possibility.

Thx, Jake  



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I forgot to post, after I mentioned the 248* trigger for the light, I did confirm it in the GM parts book, 248* it is.

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