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Discussion Starter · #1 ·
This is on my 406. I have a 'stock' waterpump, fan shroud, 6-blade flex fan, stock 2-core radiator, 160 degree 'stat. Timing is set at ~14 btdc. The problem is that when idling the temp climbs to 210-215 (then I shut it off) I have not driven the car yet, so I don't know if it will get this hot when driving. I was told to start by changing the thermostat to a hotter one, becasue my current 160 does not stay closed long enough for the coolant to cool in the radiator. Which should I try?

Next on the list will be a new fan and high flow water pump, I'd like to see if a new thermostat will help any.

I would like to drive the car to prom this Saturday, so I can't just throw new parts at it. Do you think I'll be fine driving down the highway and back roads? (read, no through town driving or stop and go driving)

Thanks!

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1971 Chevelle Malibu - 406 sbc TH350

Pictures of my '71 before I got it home
Pics of my '71 after I got it home
Picture of my 406 c.i. small block
Pictures of the frame, firewall and interior (in progress)
NEW UPDATED PICTURES (1/04/01)

ENGINE INSTALL PICS!!!
 

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I'd go with the 180 stat. Other than that you're cooling system should be more than adequate. I wouldn't spend the $$$ on a high flow water pump...I believe that someone just posted about how those 'high-flow' units are worthless. You're car will run cooler when driving...I'd say drive it first and then see what happens...if you're just idling it in the driveway then it's bound to run hot...If nothing else get a 3 or 4 core radiator...that's your weakest point right now...

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1969 Caprice (It's not an Impala darnit!)
427/M-20 Finally!
12-bolt 4.10 Posi
13.45 @ 105

1966 Caprice
396/325 TH-400
15.38 @ 97.4

Andy and Nick's Muscle Car Half-way House
 

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Andy nailed it...if the car is sitting still in your driveway, or even worse, inside your garage, there really isnt any airflow......drive it then see.

As for preparations for your prom.......
 

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1970 Chevelle Convertible & 1965 Chevelle SS Convertible
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I agree on the radiator change. In my first Chevelle, years back,in the olden days, or the golden days, ok I'm not that old - I had a stock 2 core radiator on my 350 - it was fine when the motor was stock. As soon as I started modifying, new cam, carb, manifold, timing changes - the radiator was just not enough. I went with a 4 core and I had a 180 stat - problem solved.

Hope this helps Adam - lots of luck and have fun at the Prom.

Rich


P.S. I forgot to add in - as others advise - make sure you have a shroud.
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70 SS - L34
Member # 442
www.chevelles.com/showroom/richr1

http://www.my70ss.com

[This message has been edited by richr (edited 05-03-2001).]
 

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Adam, find yourself one of those stock 4 blade fans, DEFINTELY use a shroud, and use the 180. Motors wear less at higher temps ( to a point) and you should make more power.

FWIW, I use a 3 core, 4 blade, shroud and a 195 ( aluminum heads want heat) and its rock steady at idle, in heavy traffic, whatever. When I joked about my "school bus fan" ( cause it pulls so much air it sounds like a school bus)many members here piped up and said they run the same 4 blade /shroud and never have a problem. A few of those boys were from Texas. Hey if it works in Texas heat, it'll work anywhere.

So I;m with MalibuJerry, lose the flex. Quick. The 4 blade came on many trucks applications as well, so it should be easy and cheap to find at a junk yard. Make sure the fan is spaced so it comes close to the rad, like withing 1-1.5". Hope you have a shroud, they are key.

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Gene Chaas
Gold Member 62/ACES 3112
67 SS 427
"Be big. Be a builder."

[This message has been edited by 427L88 (edited 05-03-2001).]
 

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well if you cant afford the 4core, you might have to recore yours ($100 +/-). DEFINITELY replace the flex fan, and make sure your shroud is right. If you can afford a 7blade fan get it! Take your thermostat and put it in a pan of boiling water, make sure is opens. Do use silicon sealer on the thermostat housing when you put it back. And are you sure the hoses are good. or borrow your Dad's Vette for the prom
 

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You didn't say if you were running a shroud or not. I'd go with the 4 blade fan, make sure you are running a shround that fits correctly and spring for a 4 row radiator. You won't have any more cooling problems
.

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Phil
"I don't believe I'da told that"
 

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Adam. Go with the 180 thermostat. Remember that your engine is new and you really need to drive it around to break it in all the way. A new engine is going to run a bit hot for the first little while of operation. I would suggest thet you back off your timing a bit until you run your motor for a while. what is your total, 36? I'm no expert, but I would say that 14 initial is a bit high.
 

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hey you could just do what i did and not take your girlfriend to the prom this year. you could put the $300+ you save towards your car!
 

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Dude:
I have a 71 small block and a 69 big block - both run excellent - even in slow traffic - with 180°F thermostats and stock rads, even when the temperature is pushing 90°F.
Gotta use the proper fan shroud though.
Good Luck! Have fun at the prom - but keep it cool behind the wheel - the cops will looking to make an example outa the first guy to cut er lose.


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'69 SS 300 Deluxe / '71 Malibu 2DR HT
"Never let fear and good judgement hold you back."
 

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Correct me if I'm wrong, but on the 1967 model Chevy switched from 180 to 195 degree thermostats, with the reason being faster engine warm up, plus elevated oil temp to improve vaporization of oil contaminants (and less crankcase dilution due to water vapor). I also understand that an engine at proper operating temp. delivers better fuel economy and produces more power (I said proper operating temp., not too hot!). This change occurred when Chevy relocated the thermostat to a hotter area in the head and gained tighter control of the peak temp. Of course it is academic since we all change our oil religiously and give our mills vigorous workouts to keep them operating in an efficient manner

The thermostat is one thing but the ability to shed heat when the need arises is another. A radiator with greater frontal area increases efficiency; I'm a little torn as to 3 vs. 4-core rads since the additional row increases resistance to air flow and thus lowers slightly the ability to transfer heat efficiently (I'm thinking of diminishing returns here). A shroud is most helpful in increasing cooling efficiency, especially at low speeds. Flex fans make me nervous; better to go with a viscous fan or an aftermarket electric fan (in place of or in addition to stock). Chevy engineers slowed down the water pump rate (at a constant rpm) on faster revving engines so that at least the coolant would spend enough time in the rad to actually throw their heat. My inline six is a slow revver and as such got a faster rate pump (since the engine was unlikely to spin that fast).
 

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Well, I run a 195 stat in my 406 for the reasons of better efficiency (mpg) and burning contaminants off engine oil. I've never seen more than 205 degrees on the gauge (and that was on the highway, cruising at 3,600 rpm for an extended period), in town it usually will only get to 200 degrees.

I don't think Team Chevelle members should rest until all members get those bogus flex fans removed. In simple terms, the flex fan "seems" like a good idea, but does not work like most people would expect that it does. One of the "secrets" of stock class racers is that all winners use factory style viscous fan clutch and fans - because it makes more hp than flex fans which can never decouple at higher rpm like a viscous fan clutch. You will experience superior low rpm airflow with a factory style clutch fan setup - so now you can be a winner on the street and the track.

I also took the extra step of adding additional cooling lines to the rear of my cylinder heads (I didn't want my 406 to be a "heater"). Depending on your intake manifold, this may be a low dollar upgrade using hardware store components (no need for one of those braided steel kits).

Stock two core, seriously? Well that won't work, as noted above, many low performance Chevelles ran hot because of that economy production part.

Oh yeah, it may not pass concours judging, but you can get a perfectly fine factory style fan clutch and fan from most parts houses - I think I paid $65 from a local branch of a national chain. Make sure that as installed, that the fan blade is ~ 1" from radiator, any further and it starts getting inefficient at low speed airflow. Alternatively, run the appropriate fan shroud to help airflow efficiency (I have not installed a shroud, keeping fan close to radiator works for me).

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"Bomber" '67 El Camino, Beater comes back to life.
Was 350/TH350 14.90 @ 93mph, 360,000+ miles on car
Now 406 roller, 340rwhp, more hp on its way :)
Street radials, 2.48 second 60', 13.31 [email protected] mph
 

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Discussion Starter · #16 ·
UPDATE: I drove the car for the first time saturday, it was a 20 mile trip. I put in a 180 thermostat and the temp stayed between 170 and 180. I even had to stop and wait for a train - no problems. I think I will switch to a different radiator at some point in the future - just for extra insurance


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1971 Chevelle Malibu - 406 sbc TH350

Pictures of my '71 before I got it home
Pics of my '71 after I got it home
Picture of my 406 c.i. small block
Pictures of the frame, firewall and interior (in progress)
NEW UPDATED PICTURES (1/04/01)

ENGINE INSTALL PICS!!!
 

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Getting it ready for the prom? That's easy!! Armorall the back seat!!
 

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But only if BOTH of you are above the legal age of consent of course!!!
 

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Those wheels look real good.But im sorry to tell you it won't last.I bought a set of US Wheels just like you have.in less than six months they started to rust badly.I even waxed them before i put them on and every two weeks after.I contacted summit,where i bought them, with my complaint and they told me 90 day warranty.so as soon as you see rust do something!I had mine on a BroncoII and it was winter,maybe the road salt helped,but i was bummed anyway.

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70 chevelle,400cid turbo400.blue with silver stripes.
www.members.spree.com/entertainment/ochrisl/
 

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Hey guys ive got a 7 blade off my stock motor that i have been afraid of putting in place of my flex. will rob too much hp or will it work ok. also should i use a thermal fan clutch or the rpm one. summit has two different ones and i wasnt sure.

well..... i could save that 300 bucks for prom and put it towards the 2500 i owe my parents.... hmmm... but then again that would defeat the pupose of the back seat...

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70 Chevelle ZZ430
My Ride
 
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