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Discussion Starter #1
I have 1970 454 and fan makes more noise than the engine, a lot more. It has a heat clutch and at about 75 it stops whirring the rest of the time it drives me nuts. Has anyone installed either preformance fans or electric fans? Of course the engine already runs at 215 degrees on the gauge.
 

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first i would check to see if the gauge is accuate. If it is i would then find out why it is running that hot, bad t-stat, plugged radiator, or you may need to step up to a 4 row radiator core if it does'nt have one already. The electric cooling fan would'nt be a bad idea either. most systems are wired with a thermal switch in the engine that grounds a relay that runs the fan motor. good luck :)
 

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first i would check to see if the gauge is accuate. If it is i would then find out why it is running that hot, bad t-stat, plugged radiator, or you may need to step up to a 4 row radiator core if it does'nt have one already. The electric cooling fan would'nt be a bad idea either. most systems are wired with a thermal switch in the engine that grounds a relay that runs the fan motor. good luck :)
 

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Running an electric fan is a great idea. You can get them cheap at junk yards. Get a 16in from a v6 or v8 car. A later model camaro is a direct fit but other makes & models can be modded to work.
 

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I had a 4 core radiator with electric fans on my big block and had problems keeping it cool, especially in town and in traffic. I installed a 7 blade 427 factory fan and clutch and a new (aftermarket) shroud and solved the problems. If the fan is not freewheeling as you come up to speed (the noise), the fan clutch is bad. You can get a replacement fan clutch at any parts store. As to the temp, 215 is probably a little hot for going down the highway, but is not the least unusual for a big block in traffic. Remember, with a pressurized system, the water won't boil until about 235 or 240 degrees. The other, and most obvious thing to check is that the radiator is full. If I drain mine, even after I refill it, I always have to refill the overflow tank the next 2 or 3 times after it cools down after driving it because it takes more water. I don't know where the air problem is in the block, but after the 2 or 3 times the levels stay where I want them to be. Last, be sure you have a good thermostat. I run a 160 down here in FL.
 

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Discussion Starter #6
Thnaks for all that advice. FYI I had an 85 vette that ran at 210 degrees normally, as I remember at the track one day it was upto about 230 or so, but that was unusuall. I was told that Chevy big blocks cannot be expected to run the normal 185-90 range of other engines, I am curious if anyone know more about this

Ruti
 

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You haven't stated if this vehicle is all original or has been modified. Do you have the fan shroud installed? Not having the fan shroud will definately cause the engine to run hot and possibly overheat. If this is the original radiator it could be badly corroded inside and may need to be replaced or at least cleaned. If it does need to be replaced going to a 4 row aluminum will help keep in cool. Also if this is the original clutch type fan, it may be time for a new one...they do wear out (and usually make noise when they do). If the engine has been bored out and depending on how much this also could cause the engine to run hotter (are you the original owner or do you know if the engine has been rebuilt by a previous owner). If the engine was rebuilt and only bored .030 this shouldn't effect cooling, if it was bored .060 or more it could. Replace the thermostat with a 160 deg and run a higher percentage (75%) of coolant. Just some ideas and some things to check. :)

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I think this is the first time I disagree on something Mike has said. You should run run a less amount of antifreeze. Only run enough antifreeze to lubicate & keep the rad & block from freezing. I have read to use 30 to 40 percent. Also I am usually skeptical about additives but Redlines Waterwetter works very well. It made a difference in mine. I know a electric fan worked really well on my small block but if you have a built big block than a new 7 blade clutch fan is hard to beat. I had a 69 SS396 with a built 402 that had heating problems. A new rad, therm & coolent did not help untill I changed the clutch on the 7 blade fan. It solved that problem.
 

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Discussion Starter #9
More tech stuff

I am trying to find a link I read a couple of weeks back where this gear head changed fans on a small block and took dyno readings. I understand that dyno's are notoriously un-reliable, however this guy was able to determine that the factory seven blade fan was eating up 38 horspower by far the highest loss, he also had heating problems when using after market performance fans, but ended up using a fan that only robbed 21 HP and still kept cool. I have heard both good and bad results from electric fans, maybe I get 400 watt stereo to drown out the sound of the fan, I also am concerned about staying stock, The previous owner went to great lengths to do so. Perhaps the heat clutch is the place to start

thanks again

Ruti
 

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I think 38 HP loss is way too high, but remember you also lose power when it runs too hot and even worse those lost HP will look pretty cheap if you have to spend 3 grand to rebuild it. Also, don't lose sight of the fact that with a clutch fan, the fan freewheels after you come up to speed and uses just about 0 HP. I'll admit that electrics do the same thing as far as HP goes, but cooling a big block is a completely different animal than cooling a small block. It is possible to get some electrics that will move as much air as a 7 blade, but they're big bucks and you still have to be absolutely sure that the shrouding is right so that the fans are sucking all of the air through the radiator and not around the sides where it doesn't do you any good. Part of the problem with most electrics is that they set so close to the radiator that they actually only move air through the part of the radiator that they actually cover, which may only be 50-60% of the actual core. The 7 blade sits back farther and with the right shroud, uses the whole core surface for cooling. Last, but certainly not least, the cooling fan only serves a purpose below maybe 35 mph. Faster than that and the natural air flow from the car moving through the air is giving you your cooling and the fan is really doing nothing. If you're overheating when cruising, the problem is not the fan, although as I think I commented in an earlier post, 215 is not outlandish for a big block, especially if its been bored/ built more than stock.
 
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