Slots in the Shroud or Flappers? - Team Camaro Tech
Heating & Cooling Heating, cooling and air conditioning

View Poll Results: What are peoples thoughts:
Add some slots to allow the air out? 0 0%
Add some square holes that are covered by flappers like what some factory shrouds have? 4 100.00%
Voters: 4. You may not vote on this poll

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post #1 of 20 (permalink) Old Mar 8th, 12, 05:52 AM Thread Starter
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Ray
 
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Slots in the Shroud or Flappers?

I am getting ready to swap my leaking stock radiator out with a new aluminum one I got.
I already have an electric fan with shroud and figure since I am making the swap I should consider adding some high speed flow through slots or flaps on to the shroud.
In case I have not given enough details about what I am referring to: these allow air to pass through the shroud when you are driving down the highway because there is not enough pass through with the fan running. They also eliminate turbalance from the fan fighting the air being pushed through the radiator from driving 60-80 MPH.
Thanks Ray
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post #2 of 20 (permalink) Old Mar 8th, 12, 09:41 AM
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Joe
 
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Re: Slots in the Shroud or Flappers?

Use flaps made of a flexible rubber-like material. They should open via normal air flow at higher speed (when the fan is off), and be closed at low speed so the fan/shroud can operate more efficiently. Don't put in too many.
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post #3 of 20 (permalink) Old Mar 8th, 12, 01:49 PM
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Re: Slots in the Shroud or Flappers?

What is wrong with the stock set up...run a forum search on the subject...1st gen GM nailed the cooling system spot on and even then way over built it.

Quote:
They also eliminate turbalance from the fan fighting the air being pushed through the radiator from driving 60-80 MPH.
So what is the piont? gain a couple fractions of a mile per gallon in economy?...Maybe???

My Spelling is not incorrect...it is creative

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post #4 of 20 (permalink) Old Mar 8th, 12, 04:02 PM
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Re: Slots in the Shroud or Flappers?

If you are looking to improve cooling, maybe a look at what GM did with big block 69's with air conditioning might be of help. The sides of the radiator support got metal block off panels that went to the outer edges of the fenders, and there was a metal pan that went under the subframe and radiator support, all to force more air through the radiator. They were able to keep them cool without an electric fan, or an aluminum radiator. I understand that with just the aluminum radiator, you should be able to see up to a 20 degree drop in temperature, with all other things being the same.

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post #5 of 20 (permalink) Old Mar 8th, 12, 06:36 PM
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Steve
 
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Re: Slots in the Shroud or Flappers?

What are you trying to accomplish with this modification? Better cooling or improved aerodyamics?

69 Pace Car and 69 Hard top
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post #6 of 20 (permalink) Old Mar 9th, 12, 06:35 AM Thread Starter
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Re: Slots in the Shroud or Flappers?

My 69 Firebird with 400 engine, Vintage Air A/C has the bottom close off plate in the nose along with the 2 top block off plates. I have a Mark VIII fan and shroud wired up.

On days of 90 degrees and above in Austin, TX driving down the Highway in 4th gear doing 70 MPHs with engine turning 3100 RPMs the temp gauge will start climbing from 160 towards 230. Now it takes about 20-25 miles for it to get near 230 degrees. Once I am off the highway the temp will start dropping back down and actually work its way down to about 175 within 5-10 minutes of idling(I have a 160 T-stat and the temp sensor switch is a 180/175). Also have a Edlebrock High flow water pump installed with March Serpitine kit that has a under-drive pulley.

The radiator swap is because the stock 1 is leaking at the weld for the drain plug threads.

The purpose for asking the questions in the poll is to allow more air to pass through on the highway. I have had a several people tell me not enough air is passing out of the shroud; since I have the proper close off plates installed and the electric fan is cooling the temps so quickly. These folks are builders of Radiators and Pro-touring cars and such.

So I was planning 2 small sections in opposite corners of the shroud that would allow more air flow on the highway to pass through the shroud.
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post #7 of 20 (permalink) Old Mar 9th, 12, 11:39 AM
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Re: Slots in the Shroud or Flappers?

Why run a 160 thermostat..the normal recommened is a 180 and ex factory either a 180 or 195.
There is more than enough room to move air thru the radiator at speeds over 30 /40 mphs..If it is heating up then either there are blocked cores in the radiator ineffect reducing the size of the radiator, the radiator is incorrect application or the bottom hose reenforcing spring has corroded and dis intergated sucks partly closed at rpm....and the bits block the cores

Quote:
Once I am off the highway the temp will start dropping back down and actually work its way down to about 175 within 5-10 minutes of idling
5 to 10 mins at idle is one hell of a long time...a good radiator will drop highway temps withing 1/2 to 1 min max......and at idle u far less air passing that u would at a higher speed..which indicates the above or you have something serious wrong in the engine its self..like timimg way the hell off or mixtures way the hell out on the cruise circuits..or both.

I believe u are chassing up the wrong tree here....
Test your theory, remove the shroud and head out on the highway...the ultimate open flaps right?

Quote:
The radiator swap is because the stock 1 is leaking at the weld for the drain plug threads.
So I gather u dis not have an issue before and now u do...And replace a raditor because of a leak around the drain plug...thats crazy...a minor and inexpensive fix.
If u didnt have an issue before and now do , with the same air flow, but a radiator that is meant to have better cooling properties .....doesnt add up.

My Spelling is not incorrect...it is creative

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post #8 of 20 (permalink) Old Mar 9th, 12, 11:54 AM
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Re: Slots in the Shroud or Flappers?

Ya I agree with Steps as far as testing. Make sure this is the issue by removing one or more of the block off plates and retrying your highway run and see if the temps still climb. If not then I would do the flaps, if it still gets hot than start looking at other areas like the lower hose collapsing


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post #9 of 20 (permalink) Old Mar 10th, 12, 09:36 AM
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Re: Slots in the Shroud or Flappers?

Back to my earlier comments.....on my 350 electric fan setup I run dual fans, have 4 rubber-like flaps installed (approx size 1 1/2 x 2 1/2 each), run a 180 thermo, fan on sensor at 195, off at 180. Have my vintage air set up to turn on one fan automatically when the air cond. is on & cut in the 2nd fan if temp sensor hits 195. I have a baffle between the fans in the shroud. Some guys like to keep the cooling system (& rest of car near original) and thats great. However, some like me, like to play with our cars and experiment with different setups. This is my 8th old car. Some I've kept original (all NOS), and with some others I've played around ......i.e. chopped the top, lowered, added fuel inject, different chassis, etc......it's a hobby for pete's sake......until the money runs out. Should be individual taste.
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post #10 of 20 (permalink) Old Mar 10th, 12, 10:04 AM
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Re: Slots in the Shroud or Flappers?

I understand now, didn't notice you have an electric fan and shroud set up. A stock shroud and fan set up wouldn't block the flow and would be fine on the highway as well as around town.

69 Pace Car and 69 Hard top
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post #11 of 20 (permalink) Old Mar 10th, 12, 12:39 PM Thread Starter
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Re: Slots in the Shroud or Flappers?

This problem has existed ever since i got the car except for the leak. When I got the car it had the factory fan and shroud. The hoses were replaced and flushed shortly after I got the car, 3000 miles ago.
There is no one in the area that I trust to weld up a hole in brass to fix the leak. Considering how old this radiator is I would just rather replace it with a new one.

Every SBC I have ever ran I put a 160 T-Stat in them so I did the same with this 400 engine. Even do the same thing with my Dodge Viper and my LS based Corvettes.
They have made a huge difference with the summer heat we have here in Austin. Normally about 30 degrees cooler in 100 temps in rush hour traffic.

Timing on the engine is at 12 degrees and the engine has a little bit of running rich smell from time to time.

Very good chance the core tubing is clogged considering some of the other things I have had to correct from the previous owners way of having the car.

Yes I also know about the infamous Pontiac Water Pump separator plate fix and discussed this in great detail with Edelbrock since it is their water pump.

Thanks
Ray
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post #12 of 20 (permalink) Old Mar 10th, 12, 03:51 PM
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Re: Slots in the Shroud or Flappers?

What is your total advance at 3000 rpm with the vac disconnected? If you are much under 36 I'd advance the timing some, but if your radiator is clogged up that could certainly be the problem. I've never heard of one overheating on the highway before if it did ok at an idle.

For reference, I have a 408 that dyno'd 450hp / 500 ftlbs of torque at the flywheel and it has no problems overheating on the highway or idling with a BBC Alumitech radiator. it's cooler in iowa obviously but still you shouldn't have a problem with a factory set up all else being set right with a clean radiator.

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post #13 of 20 (permalink) Old Mar 10th, 12, 09:56 PM
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Re: Slots in the Shroud or Flappers?

Quote:
I've never heard of one overheating on the highway before if it did ok at an idle
I have...lol that is what made me chase my A55 back in the early 80s thermstats , no thermostats , shrouds radiators etc...like many here went the full cicle and back to the 50 yr old technology that still works better than anything today.

My Spelling is not incorrect...it is creative

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post #14 of 20 (permalink) Old Mar 12th, 12, 05:57 AM Thread Starter
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Re: Slots in the Shroud or Flappers?

The MSD distributor has no vacuum advance on it. I also have never check the advance at 3000 rpms because the advance tab on the motor only goes to 15 besides being impossible to see due to all the pulleys and stuff hiding it.
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post #15 of 20 (permalink) Old Mar 12th, 12, 07:22 AM
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Re: Slots in the Shroud or Flappers?

Ray I would go ahead and swap out the rad and see out it affects the heating at speed issue. If you still have it I would remove one of the block off panels and see if it makes a difference before creating a flap system, if it does create the flaps and put the block off back or just leave the block off panel out. Also to check the "all in" timing you can use a dial back light, unless you have a MSD box as they do not play nice with the dial back lights. If that is the case you might as well get some timing tape for the balancer, its cheap and easy.
Here it is for 10 bucks at Autozone
http://www.autozone.com/autozone/acc...er=139829_0_0_

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