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Author Topic:   cooling problems
chuck69
Dirt Newbie

Total posts: 3
posted January 24, 2001 11:59 PM
my partner and I run down in Lubbock, Texas.....and on Friday nights in July and August.....the ambient temperature at 10 p.m may still be in the high 80s......down from 100 or so when we pack the track and run hot laps......so cooling is a big problem.....any suggestions on how to keep our 79 Firebird/350 Chevy/4 bolt main/Quadrajet/cast iron exhaust and intake.....from overheating..would be greatly appreciated.....we run an aluminum radiator, crank reduction pulley, steel fan, etc...but still come in hot...as do a lot of others.....thanks.....Chuck.....

awkwardjeff
Dirt Freak

Total posts: 218
posted January 25, 2001 12:09 AM
Chuck, buy a new radiator......AFCO PART NUMBER 80126 if your 31 inchs wide..... 801125 if your 26 inchs wide............
Both of these are called double pass radiators, the top hose and bottom hose are both on the right side, there is a baffle half way down the right side tank that forces the water to the left side then across the center of the radiator a secound time for the water to cool another 30% ..
This is what guys in BIG BLOCK east coast mods do to keep cool running 14 to 1 on gas.
Jeff

jammin
Dirt Administrator

Total posts: 3279
posted January 25, 2001 12:12 AM UIN: 16262997
I went thru this same type scenario with a 406 in a street stock Chuck...one, you get rid of the reduction pulley...it will not turn the fan fast enough to pull enough air in through the radiator....make sure you have a rigid(no flex) fan with 5 blades or more....your pulleys need to be at least 1 to 1 if your running gas...so you will need at least the same size pulley on bottom that you have on top. These reduction pulleys are for alky engines and they will not pull as much air or keep as much block water pressure. We went to about a larger crank pulley and a smaller water pump with a 6 blade rigid fan and you could pull the dirt out of the radiator with it...had no more heating problems...Make sure you have a shroud that cuts your blades in half on depth. Timing will do it, fuel starvation will hurt you...there are several engine problems that can contribute also.

hope this helps.

jammin

VIPER000
Dirt Maniac

Total posts: 151
posted January 25, 2001 06:54 AM
I HAD THIS PROMBLEM AS DID SOME FREINDS. FIRST GET RID OF THE REDUCTION, MAKE SHORE YOU DO NOT HAVE A FLEX FAN THEY ARE JUNK. AND THE MOST IMPORTANT THING IS MAKE SHORE YOU HAVE A GOOD SHROUD. I CANT STRESS THE SHROUD ENOUGH. ALSO IF YOU HAVE A STOCK RADIATOR MAKE SHORE IT IS AT LEAST A 3 CORE. ANY LESS AND IT DOES NOT HAVE A CHANCE.

BDS
Dirt Roller

Total posts: 7
posted January 25, 2001 02:50 PM
exactly right guys. i learned a few years ago from talking to howard stewart over the phone that performance of this type requires zero pump reduction, a good shroud, a good pump, good radiator and most of the time no restriction in the therm housing will be a big help. stewart says get the water out of the block as fast as you can and let a good radiator do its job. Also anything to make the water more slippery will help.

Limited5
Dirt Maniac

Total posts: 141
posted January 25, 2001 06:04 PM
This may not be your problem but may help you in the future. I battled a heating problem for a month. I tried the usual stuff, like restrictors, fan, hoses and jetting with no luck, even tried changing the timing. After much frustration and trying everyones suggestions, a guy parked next to me suggested holding a light up against the radiator to see if the cores had swelled. Cores swelled? I never heard of such a thing. Well guess what, I held a light to the radiator and found no matter where we looked no light would shine through.I replaced the aluminum radiator and my heating problems were over. I bought a Howe unit and I now have to block the front prior to racing inorder to get it up to temp.

I use a 1" restrictor and a 4 blade fan with reduction pulleys and the front completely closed on gas and no shroud. It has never gotten above 195 even on 90 degree days. The trick is to get the fan within 1/2 to 3/4 of an inch away from the radiator. Look at a UDTRA car sometime, they all use the same type of setup and it works!

24Crew
Dirt Roller

Total posts: 17
posted January 25, 2001 06:18 PM
Chuck69, we fought similar problems last year in southeast Georgia. Of all that we tried there were two things we found that helped us. First getting the fan closer to the radiator like Limited5 said. The second was to build a shroud around the fan, this will help the fan push the air from behind the radiator and force more air to be pulled from in front of the radiator. We made our shroud from sheet metal from an AC duct, not pretty but simple and easy to make and very effective.

MOD RACER#93
Dirt Freak

Total posts: 251
posted January 25, 2001 07:59 PM
Get the 1 to 1 pulleys, and sell the reduction to the mod guys. You can buy all the radiators and fans and water pumps and water wetters, but until you BUILD yourself a fan shroud you will always run hot...It took busting a block for me to finally get down and just do it....When you make it do like Jammin said make sure that the fan blades are half INSIDE(the shroud) and half OUTSIDE(the shroud) and get the blades as close to the shroud as you can. If the blades hit a little, they will clearance themselves and you will be good to go...I cannot stress this enough. This is what really pulls the wind through the radiator. I guarantee you will drop as much as 60 degrees of your temperature..I did..Also on the front of your car. Go underneath and make a SPOILER or FLAP, directly under the radiator. When the air tries to go under your car this spoiler, flap will stop it for a second, and if you have the shroud described above, the fan will PULL this air through the radiator. It helps to add a couple of small alumn. braces behind so it does'nt just fold back...This will get you cool...

bbracer17
Dirt Maniac

Total posts: 168
posted January 25, 2001 09:20 PM
I ran the last 2 years in South Texas and temperetures were in the high 80's and low 90's in July and August. I ran gasoline with a 24 inch wide Griffin radiator, no shroud, 1 to 1 pulleys, steel 5 blade fan 1/2 from radiator, and 2 bottles of water wetter. My tempereture was never over 220 at the end of the feature. Also be sure to run a good 22 lb cap. This is what worked for me.

66skip
Dirt Roller

Total posts: 17
posted January 26, 2001 07:56 PM
I agree with everyone that a good shroud is very important. Another thing to watch is where your fan is located in respect to the shroud. At any RPM the fan will move about 30% of it's air off the tips, so if you place your fan about 1/3 inside the shroud and 2/3 outside, your air movement will be greatly improved.
Also, the diameter of your shroud should be only about 2" larger than the fan.
Royal Purple has a product called Purple Ice that works real good.

jklostermann
Dirt Full Roller

Total posts: 45
posted February 07, 2001 02:39 PM
Chuck

We ran a street Stock one year ago and had some of the same problems. However unlike some of the other guys above we solved the problem a little differently. We ordered an electric Fan, when the car gets warm flip a switch and the problem is solved. However, this brings about another problem. Keeping your Batt. charged. So if you don't have a generator this will not work!

Pickel
Dirt Freak

Total posts: 239
posted February 07, 2001 06:45 PM UIN: 25419780
I ran in to the same thing as chuch did.. I have tried every thing we all suggested and still one week it would be fine (about 180 190)and the following week its back up to 210...any ideas...

jammin
Dirt Administrator

Total posts: 3279
posted February 07, 2001 06:59 PM UIN: 16262997
Pickel...it could be that your sucking air somewhere around your intake..vacuum leaks will cause it to lean out a little, making it run warm. Air density makes a difference too....if the air density is high, it will need more jet in the carb to stay cool...It makes me wonder...sounds like your on the verge of possibly running lean. I would try going up a notch on jets and see if it helps.

widebody
Dirt Full Roller

Total posts: 74
posted February 08, 2001 03:06 PM
Some things to check that get overlooked:
Radiator cap, NEW doesnt = GOOD.
Keep the fluid level up.
How the Air flow to the radiator?
Do the paper test. Hold a piece of paper in front of the rad. It should drawn in.
What type of nose do you have on the car? And do you have it ducted to the front of the radiator.
We made a nice duct from lexan and zip ties for the car, takes a beatin and goes back together again. Another good material for shrouds and duct work is old conveyer belt material or other industrial belting materials. Use fender washers to fasten it, its rigied yet flexible. Doesnt weigh alot either
On the firbirds cut some holes through the bumper with a hole saw. It helps a bunch.

Other than that sounds like everyone covered the basics.

Pickel
Dirt Freak

Total posts: 239
posted February 11, 2001 08:38 PM UIN: 25419780
Jammin
I have changed the intake and checked every thing possible... I finally said the heck with it as long as it did not get over 220 I was happy.

jammin
Dirt Administrator

Total posts: 3279
posted February 11, 2001 09:12 PM UIN: 16262997
One more thing pickel.....make sure you bring your rpm's up enough when you check your timing....if you dont, it might not be fully advanced and may be showing you something other than the truth on the advance... Still thinking.

jammin

awkwardjeff
Dirt Freak

Total posts: 218
posted February 13, 2001 12:13 PM

Jammin, this is for everyone's information.
And not completely on a cooling problem, but you mentioned a intake leak.........
I see this a lot with people that angle mill the heads and don't correct the intake to fit the heads properly........
Also we have a few times over the years had the intake leak inside......from the valley of the motor...........One motor we had was a little more than 15 to 1 compression.....
I found the intake was pulling oil from the valley after a heat race and when I shut the motor off it kept running like a diesel truck.

I just thought I would mention this for other people out there to remember this when the are having a problem. It's some thing most people don't even think about......
Jeff

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