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jo0oj
Tribal Scout

Germany
38 Posts

Posted - 14 Aug 2009 :  05:47:33 AM  Show Profile  Reply with Quote
Hi all,

I rebuild my engine at the moment.
In the past i had some problems with the temperatures.

the engine is an 400 block with
Ohio Crank 4.21 stroke
Edelbrock heads 72cc
KB Dished Pistons +30,5cc

The Water Cooling system is an overhauled radiator with mechanical ventilator

The Water have
60mph = 160F
30mph = 180F
City = 210F

What should be the optimum temperature for the water?
What should be the max temperature for the water?
What can i do to reduce the Water Temperture in the City?

thanks for your help
Jo

68 GTO 462

Bill Boyle
Horse Feathers (Charter Member)

USA
4794 Posts

Posted - 14 Aug 2009 :  06:08:39 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Your thermostat is opening late or not opening enough. Check it with a thermometer in a dish of boiling water. Run a 160 thermostat.

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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jo0oj
Tribal Scout

Germany
38 Posts

Posted - 14 Aug 2009 :  06:13:06 AM  Show Profile  Reply with Quote
I will Check it.
Additional i will think about an electrical fan.
What is the target temperature for water which will i get?

68 GTO 462
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bnorris_74
Crazy Horse

USA
1442 Posts

Posted - 14 Aug 2009 :  07:37:48 AM  Show Profile  Reply with Quote
Measure your crank and water pump pulleys too.
A lot of overheating problems occur at highway speeds. Yours is the opposite.
I would guess your pulley sizes are not spinning your water pump fast enough at near idle speeds (city driving)

Take a look at the discussion on this site: http://forums.performanceyears.com/forums/showthread.php?t=603340

To answer your question on ideal temps, you can certainly survive with 210 city temps but since you can achieve lower temps at higher speeds, I think you could realistically run at 180-190 city too.

Edited by - bnorris_74 on 14 Aug 2009 07:41:08 AM
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RayK
Cochise

USA
925 Posts

Posted - 14 Aug 2009 :  08:45:52 AM  Show Profile  Reply with Quote
I agree with checking the pulley sizes, also what kind of cooling fan are you running? I've used a 5 blade flex fan, a 1970 GTO factory flex fan and aalso an electric cooling fan next to the radiator and NONE of them cooled as well as a 7 blade factory thermostatically controlled fan. Our engines, at least through my experiences run best at about 180 degrees. Just my 2 cents worth of free adive.

1969 Firebird 461, #62 iron heads, Comp roller, Performer RPM, Q-Jet Turbo 400 w/ Continental converter. GM 8.5" 10 bolt with 3:73 gears.11.50's@ 119+ MPH
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jo0oj
Tribal Scout

Germany
38 Posts

Posted - 14 Aug 2009 :  10:14:20 AM  Show Profile  Reply with Quote
i Run March Performance Pulleys. Both have 6 1/8".
for the rebuild i will think about an flexalite mechanical 7 blade with thermostatic clutch or flexalite electric dual fan

68 GTO 462
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Phil
The Great White Buffalo

USA
7215 Posts

Posted - 14 Aug 2009 :  11:00:12 AM  Show Profile  Reply with Quote
Another vote for the factory 7 bladed clutch fan. Make sure whatever fan you use is half in and half out of the shroud. And further to Brians point, if the pully is driving the water pump too slow it is also driving the mechanical fan slower which could intensify the high temp. effect at slow speeds and idle.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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bnorris_74
Crazy Horse

USA
1442 Posts

Posted - 14 Aug 2009 :  11:45:16 AM  Show Profile  Reply with Quote
quote:
Originally posted by Phil

if the pully is driving the water pump too slow it is also driving the mechanical fan slower which could intensify the high temp. effect at slow speeds and idle.


Excellent point.
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jo0oj
Tribal Scout

Germany
38 Posts

Posted - 14 Aug 2009 :  1:40:06 PM  Show Profile  Reply with Quote
where do i get the factory 7 bladed clutch fan?
what do you think about the dual electrical fan?
what do you think about to additional open the scoops?

68 GTO 462
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RayK
Cochise

USA
925 Posts

Posted - 14 Aug 2009 :  2:23:39 PM  Show Profile  Reply with Quote
There is debate about the scoops in the GTO hoods being functional being they are towards the center of the hood in the "dead zone" so to speak. They wouldn't be any good for cooling anyways. I would honestly go with the factory 7 blade clutch fan deal. Sometimes you can find them on Ebay or at a swap meet.

1969 Firebird 461, #62 iron heads, Comp roller, Performer RPM, Q-Jet Turbo 400 w/ Continental converter. GM 8.5" 10 bolt with 3:73 gears.11.50's@ 119+ MPH
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Luis Cervantes
Cochise

USA
286 Posts

Posted - 14 Aug 2009 :  2:40:34 PM  Show Profile  Reply with Quote
It all depends on where your temp. gauge sensor is located. The most important reading is at the head where GM put it. If you are reading at the thermostat housing area, then you are actually getting the temp. of the coolant/water after it has pulled away the heat from your engine. I have a sensor in both these areas. My temp. at the intake/thermastat housing is usually measures 15-20deg.hotter than the head sensor. This difference in reading gives a good idea as far as how efficiently my cooling system is working. In extremely hot weather 100+deg./driving hard up hills and coming to complete stops and idling in traffic, I have seen both temps. go 1:1 ratio (200deg.head to 200deg.). But this is rarely seen on my 400 with 9.1cr. I am currently using the original 76 cooling system with shroud and heavy duty clutch. However, worrisome as I am, I run a pusher fan (1800cfm 16in.electric)in front of my radiater with a maual switch at my reach. It is great to have when you have to idle for long periods in L.A. summer traffic. The electric fan is good for 10-15deg.lower, it works great at maintaining your last temp. prior to stopping/idle from rising, but minimal if you use it after the temps. have went up. My 75%distilled water/25%coolant cools the temps. once cars starts cruising along by scooping up more air through the radiater and then it finally settles at a comfortable temp. I usually only need the electric fan on 100deg. days. Hope this helps.
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jo0oj
Tribal Scout

Germany
38 Posts

Posted - 26 Aug 2009 :  08:53:10 AM  Show Profile  Reply with Quote
thansk for your infos.
i will keep the manual blade fan and add an electrical pusher with an manual switch to the frontside and wid will look what happen.

68 GTO 462
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Total Jackass
Tribal Scout

0 Posts

Posted - 14 Jan 2014 :  04:09:52 AM  Show Profile  Reply with Quote
I enjoyed this. Do you have a RSS feed?.
http://www.popuwatches.com/Pershing.html

I'm a first class jerk and don't you forget it!
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Phil
The Great White Buffalo

USA
7215 Posts

Posted - 14 Jan 2014 :  6:33:10 PM  Show Profile  Reply with Quote
TTT

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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