Section A - Cooling System, continued.....

Subject: Re: Engine bore and heat Date: Tue, 05 May 1998 11:01:17 -0700 From: Allan Connell To: Steve Laifman References: 1 , 2 , 3

Steve,
At 09:06 AM 5/5/98 +0100, you wrote: > > >Allan Connell wrote: > >> Steve, >> >> .... During the original install, had to tilt the radiator toward the >> engine... > >Permanenetly? >
Oh no, no way!! Just to do the install. Bolted the radiator back into the original holes......
>> . If you want the model number on the Hayden >> fan, judt let me know. >
Ok, let me go get the thing and I will try and answer your questions.....just a sec....
Model # is: Haden 3690. Got it at Auto Parts Club (APW to you??)
> >> Allan >> B9472373 > >Yes, please. BTW. Did you use rod or mechanical mounts, or run a nylon strap >through that $300 radiator?.
Nylon "rods" go though the radiator and are secured by a foam backed clip, similar to a spped tie. Springs are compressed on the fan side to make for a secure fit.
>Is their a shroud around thge Hayden?, are the >blades connected to an outer strengthening ring? Are the blades curved?
Yes, yes and yes. Though the fan is stated to be a 15", the shroud is actually 14.5" and the fan itself is about 13".
> Did you >use foam to seal the shroud(?) to the radiator?
No, once the spring clips are compressed, it fits flat against the radiator. As well, upper and lower mounting flanges are large enough to give a secure fit against the radiator without impeading too much air flow.
>Did you use a thermal switch >(temp settting?) along with a manual one? Is it "originally" a pusher, or did >you have to futz with it by reversing the blade or polarity? What are the >"real" outside dimensions? >
Used a thermal switch that (I think) came with the unit, but different models and temp settings are available separately. The thermal switches DO spread the fins back a bit as it is about 3/8" in diameter, unlike the nylon "rods" that secure the fan which are a bit over 1/16" in diameter. I added an over-ride switch to the circuit that I considered to be essential. Simply added it to the "Air Conditioning" override circuit included with the thermal switch. The fan is definately a pusher, and considering it is a DC motor, I am not sure that reversing is a real good idea. I spun it backwards manually and it made a helluva racket.
>I am kind of leaning towards a DeRale "Tornado" because it has these features, >although somone claimed curved blades are quieter, but less efficient. Not sure >I believe that. The ony Hayden in PAW is a dual 12" swept blade for $130 (2000 >CFM), but I'm not sure I've got the width. A pair of 12" DeRale are $162 plus >mounting and control. Tehy have 14" and 16", but no 15" (that's height to the >end of the external shroud mount bracket). "Flex-a-lite has a "15" fan >diameter, but the mount for the shroud is 17.25 highx 16.5 wide. for $125. > >I am sure my local "Le Bozy du Pep" carry Hayden. BTW, Hayden does have a >90-230 deg F adjustable fin probe control for $28. > >Steve >--
If I recall, I did see these fans at "Le Bozy du Poop" but a bit more spendy than Auto Parts Club. The adjustable fin probe is a good thing, but I found that the 195 degree fixed kicked in right on schedule. I don't recall alll of the details, but I think that the whole deal, including everything was about $120. I chose the Hayden for two reasons: 1) It had the highest CFM rating of the other available choices and 2) it has a very thin profile: about 1.5" deep at the sides of the shroud and about 2-1/4" at it's highest point, the fan motor. At this juncture, I am going to see if I can live without it....but it can be re-installed if I need it!!
Hope this helps.
Best Regards
Allan > Steve Laifman >B9472289 > >
Subject: Re: Cooling Date: Tue, 5 May 1998 12:10:13 -0600 From: johnc@nait.ab.ca To: Harold Hartsell CC: tigers@autox.team.net


Here is an article I wrote on cooling a while back. Much of this info has been posted before and it is long so press delete if you get tired of reading.
Since cooling is always a problem I have spent some time asking questions of all who could give advice on the Tiger's eternal problem of over heating
To D.C. who has had more sports cars with overheating problems than any one I have ever met. He has become our Club expert on over heating
Q. What is the "Magic Bullet" that I can bolt on and cure all my over heating problems?
A. There is no such thing. The war on over heating is won little by little, one degree at time.
To the College Automotive Department Head:
Q. Why do our engines over heat after rebuilding and an overbore of 30 thou +?
A. The closer the kettle is to the fire, the sooner the water will boil. If you overbore you need to cool more.
New engines are tight. Tight is hot. Break 'em in at night.
To the Physics department:
Q. What fan blade works the best?
A. Try an asymmetrical fan. Symmetrical fan blades set up a vortex (whirlpool of air) that is relatively stable. They move lots of air but they tend to draw the air from only one spot just like the whirlpool of water when you drain your bathtub. An asymmetrical fan tends to set up an unstable vortex that moves around, drawing air from all over the rad. The whirlpool of air from the symmetrical fan will be noisier too, just like a cyclone. The unstable vortex from a asymmetrical fan will not howl as the whirl pool is continually being changed.
TIP: Try a 140 series Volvo 5 blade, it bolts up to the Tiger engine and requires no trimming. I have one on my car and it works great. I got it for $3.00 at "Pick-Your-Part". Get the Volvo aluminum spacer. You will have to have it turned down but it fits.
Q. What do you consider the single greatest cause of over heating?
A. Rads that are plugged. Excess silicon, (widely used in engine rebuilding) tends to flake off in specs and block of the veins in the rad. If a rad has 20 veins and you lose only 4 you loose 20% of your cooling. If it worked proportionally 190


° + 20% = 228°.
TIP: Pull the rad and have it boiled. Flushing does nothing.
To an old time Rad man: who "fixes and doesn't just replace "
Q. What else can cause over heating?
A. Stoppage of air flow. Bent fins in the rad. If only one or two small areas are blocked from air flow the result can be one or two degrees of over heating. (Remember how we win this war - one degree at a time). Get a small thin screwdriver and straighten every fin. Don't forget the back side. Even a brand new core can have some damaged fins. Rad men now-a-days don't like to take the time to do this but it helps.
Also . . . An old rad can have much of the air flow stopped by bits of sand stuck in the fins. This can be removed but plan to spend the week end with a fine wire hook and use care. Boiling will not get rid of this sand, so if it's bad it may be time for a new core. And remember airflow.
TIP: Bugs on the rad stop air. Use a rad screen clean it often
To a College Air Conditioning Technology Professor:
Q. What about air flow and how does it relate to cooling.
A. Now you are asking the right questions. Air flow is everything. Air removes heat. Moving air removes more heat. (Ask us Canadians. Minus 40° can be a pleasant day if there is no wind but at minus 20 with a 10 M.P.H. wind, flesh will freeze in 3 minutes.)
Q. So how does a fan move air in the cooling system of a car?
A. Very poorly. The designs were a bit hit and miss - mostly miss. We would never get away with designs like that in the Air Con trade but then we do not have the space restrictions. Especially older cars have poor designs. Look at some of the new cars, where they want to save weight by cutting back on the rad size. The engineers compensate for this by proper shrouding.
Try This: Hold your hand up to your mouth and blow through your fist. You can feel the air with your other hand even 6 to 8 inches away. Now suck. You can not feel the air move until you almost seal your fist up tight with your other hand. A car's cooling system is the same. The fan sucks, or draws, the air through the rad. If you look at your Tiger's rad shroud you will see that it is open at the bottom. No seal to help the fan suck the air through the rad. Air does not like to go through things - It would rather go around and hence the "reverse" air flow into the engine compartment. The air is being pulled from under the rad and up through the fan. Shrouding the bottom of the engine compartment will work, to a degree, but it would be much more efficient to build a proper rad shroud, allowing the air to be drawn through the rad and then exit, out the bottom, as it should.
An electric fan works because it blows through the rad but to really work it should be shrouded to about one or two feet in front of the rad. Not practical.
Q. What is the proper shroud then for a drawing fan?
A. A proper shroud is one that is sealed up all around the rad. A rubber gasket, between the shroud and the rad, would even help. No leaks. The shroud should surround the fan completely. The fan should be housed with only 2/3 of the blades inside of the shroud. The air must be free to fly away from the tips of the fan blade. This will give you air flow at idle or at any speed.
To an Ex Rootes Automotive Engineer:
Q. Why were automotive cooling systems so poorly designed?
A. Money. Profit in automotive engineering is gained penny at a time, just as you say cooling is achieved one degree at a time. We used to design a rad that would cool an engine anywhere. Then, when the prototypes were being tested, we cut the rad back until it just worked then added a bit. Every inch of rad core or shroud material saved was more profit. Automotive design is one of cost cutting, not one of engineering design excellence. If we had managed to cut the cost of the Tiger cooling system by $10 that would have made a profit of $70,000 more during it's production run. The same $10 cut from the Mustang may have been worth perhaps $20,000,000 to Ford during the car's production life.
Remember the warrantee for most cars back then was 12 months or 12,000 miles. We never designed them to last for 200 to 300,000 miles and 25 years. Modern cars are different. Longer warrantees necessitate better engineering and plastics now allow you to design a good shroud at no more cost or weight than a poor one. It was different when metal and hand labor was used for every shroud built.
We did smoke tests on air flow and when a car is sitting at idle the air is pulled through the rad by the fan, it then hits the pavement under the car and much of it is drawn forward, back up through the rad again thus trying to cool with pre-heated air. Shrouds in front of the rad, at the bottom, did stop this on some cars but I am not sure it would work on the Tiger. I can't remember specifically working on them.

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