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Discussion Starter #1 (Edited)
Just installed a new Harwood Cowl hood on the Nova. Been driving the car for almost two years without a hood and the engine temps range from 190 to 200 degrees up to 100 degrees ambient outside. The other day driving home from a car show at 95 degrees outside the engine temp was 220. Yesterday it was 92 degrees outside and I decided to test, so, I ran the car about 5 miles round trip and when I got home the engine temp was 218. While the engine was still running I removed the hood and drove the same route, the temp while driving slowly came back down to 200. Last year we drove to a car show and it was almost 110 oustside and the car ran 215 degrees which is the hottest it's ever run (without the hood), till now. I called Steve at Harwood and he said he's never heard of this, not one time. Has anyone here had this happen to them? Very strange to me. Any air flow people on here have any ideas? Thanks! -Al

 

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Nope, but

Makes sense though. Close the oven door so to speak.
 

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That's really unusual. I have a similar cooling setup to yours. I have never seen my temps go above 190*. My fans turn on at 190 and the temp drops to 170 in a minute or two. This is even when sitting at idle in the cool So. Cal. summers.
 

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Tape some strips of paper across the cowl hood scoop opening. Drive around and see if they blow inward or outward.
I'm guessing you are building up pressure under the hood which is preventing air flow through the radiator.
You may need to find a way to allow air to vent. May be louvers in the inner fenders.
 

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Discussion Starter #6
Tape some strips of paper across the cowl hood scoop opening. Drive around and see if they blow inward or outward.
I'm guessing you are building up pressure under the hood which is preventing air flow through the radiator.
You may need to find a way to allow air to vent. May be louvers in the inner fenders.
Thanks Paul, I'll do that. I sealed the radiator and all the openings in the core support to eliminate any air leakage and it didnt make any difference. The fans are pulling a ton of air thru the radiator (3,440cfm).

 

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A hood over the engine will trap in a ton of heat. Header heat has nowhere to go so ofcourse a hood being on the car will cause it to run hotter. It will also slow down the air through the radiator.
 

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Discussion Starter #9
In the begining I figured that with the fans pushing that much air it would just force the hot air out the hood scoop, but, the function of the cowl scoop is to force high pressure air in! I have opposing forces and no where for it to go. It was suggested to me to take out the inner fender panels but I really dont want to do that. I need to figure out how to exhaust the hot air out so that it solves the heat problem and also looks good as well. Now where did that drawing board go!:rolleyes:
 

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rearward facing 3" or 2" louvers in the inner fender wells. punched outward....... seal plate from the cowl to the carb.....

random thoughts
 

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rearward facing 3" or 2" louvers in the inner fender wells. punched outward....... seal plate from the cowl to the carb.....

random thoughts
X2 What Veno said.....might give the hot air a place to escape :yes:
 

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The louver idea

Don't know how much trouble it is to remove those chasis works panels, but, before I punched holes in anything that nice I'd test how many square inches of venting I needed to exhaust the hot air.
Make sheet metal test panels using the pretty ones as a pattern totemporarily replace those pretty inner fenders. Driil a pattern of holes about where you would want the louvers. Keep drilling holes a couple of square inches at a time in the temp panel until you see results, if at all.
Once you know how many square inches of venting you need you can have the louvers punched.
I guess as an alterate way, you could also use expanded metal sheet with the holes already in it (via the mesh pattern). Mock up using the pretty panels as a template. Tape the mesh solid with metal duct tape. Remove tape a little at a time exposing the mesh to get a square inch reading.

OH, buy the way, that is one nice ride. I like the hood and what's under it.
 

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Discussion Starter #13
Don't know how much trouble it is to remove those chasis works panels, but, before I punched holes in anything that nice I'd test how many square inches of venting I needed to exhaust the hot air.
Make sheet metal test panels using the pretty ones as a pattern totemporarily replace those pretty inner fenders. Driil a pattern of holes about where you would want the louvers. Keep drilling holes a couple of square inches at a time in the temp panel until you see results, if at all.
Once you know how many square inches of venting you need you can have the louvers punched.
I guess as an alterate way, you could also use expanded metal sheet with the holes already in it (via the mesh pattern). Mock up using the pretty panels as a template. Tape the mesh solid with metal duct tape. Remove tape a little at a time exposing the mesh to get a square inch reading.

OH, buy the way, that is one nice ride. I like the hood and what's under it.
Thanks KDee for the advise! It just baffles me, that, it seems like I'm the only guy with this issue. I'm even thinking of installing pull fans on the outside of the inner fender panels on both sides with some kind of cool looking vent grills on the inside and just pull the heat out that way. I'm not a big louver fan and I'm not sure that after all that work that it will be enough. I'm not sure about much of anything at this point!:rolleyes::D But I am favoring the fan idea.:yes:
 

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wonder if

you could put a small front air dam below the front bumper , ala 70's era nascar aluminum piece to direct air toward the radiator or function as a trap to collect air in that area that would normally flow under the car , and then the easiest place for it to escape is through the radiator.

something like this
http://farm4.static.flickr.com/3147/2892212151_3b9677c279.jpg

big blocks just generate sooo much heat ,, its a definate problem
 

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Loop !

Al, I think the air flow is flowing in a " loop " Your sucking back in from the front of the radiator the already headed air from the radiator . I have seen guys make a foam air dam from the top of the radiator support to the bottom surface of the hood to solve this problem. ( like a dam ) Ever look at a 1968 - 1972 Corvette core support ? the factory put one there just for that problem. Michael
 

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Thanks KDee for the advise! It just baffles me........COLOR]


Al,
The Louvers may not look so bad.



It's not like they're in the hood. Kinda blends there.

(I got way too much time on my hands)
 

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I'm even thinking of installing pull fans on the outside of the inner fender panels on both sides with some kind of cool looking vent grills on the inside and just pull the heat out that way.
I have thought about this myself, anything that remove heat from under that hood should help cool the engine off. IMO
 

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IMO, putting fans in the inner fenders is more headache than its worth. Think of a fire, the smoke has to go somewhere. Once the flu is open, the smoke will fly through the opening. The louvers may in fact do just what you need. Just a thought. And finally, how about plumbing your intake manifold front to back at the coolant ports. More flow there will for sure help. It looks like you have plugs on all 4 corners of the intake.

Todd
 

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A simple test will prove my theory. If you can temporarily remove the inner fenders then do a test drive. If it's cooler then you know the problem is inadequate venting of the engine compartment.
 

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gotta question

looking at the pics of your engine , i don't see the water line that usually comes off of the intake and branches back to the top of the water pump. Its been a while since i've been around a big block street car ,,, i never really read up on what that water line does , unless it just helps circulate more water through the system.

I wonder if an additional heat exchanger could be fabbed and placed maybe beside the radiator using a heater core and heater hose connections on the intake and water pump that circulated water constantly. Make some good looking brackets to mount it up, box it in , place a small fan in front of it ,, , just a thought

I had a friend with a 427 in a 66 chevelle ,, it would make you nervous watching the temp gauge.
 
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