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BT7 air ducting / cooling

Drone Dog

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a while back i made a cap out of some metal to go at the top of the radiator to keep hot air from recirculating around it. i was never really happy with it because i wondered about it restricting air in to the top of the core as well.

so last week i began looking for another way to seal off the top. it probably has been done before but i have not seen it so i thought i would share. who knows it might work and it is not complicated at all.

first i made extensions to the original air deflectors that came up to the top tank. since i was not real sure of the hood position i left a little room and then added a piece of trunk seal on top. here are a couple of pictures. first one shows a trial piece and the second shows the piece attached with a rivet.
fullsizeoutput_1c6.jpgIMG_0385.jpg

Now this seemed to seal the ends of the radiator but i still had an issue with air coming over the top. So i found a larger piece of trunk seal (yes i keep everything) in a box and added it to the hood. this seal is about 7/8" to the tip of that bead. the idea here is when i close the hood, it sits up against the front of the radiator top tank and seals off the top. from under the car you can see the ends actually hit my side seals. i also put the trunk seal on those 4" edges of the hood which puts them over the top of the radiator. not sure that does any good but at the time i thought it looked better. anyway with the hood down and the car idling you can feel quite a bit of air being pushed out of the hood grill. that should be a good thing. a couple of picturs of that.
IMG_0382.jpgfullsizeoutput_1d1.jpg

could not get my finished picture to load so the second one is when i was first pushing the seal on. with this seal i want to leave it just a little off being pushed up tight so it hits the tank. i am looking for another seal that will fill the distance and be tight. but for now, this will work.

hope this can help someone who is no more a metal worker or painter than i am.
 
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Drone Dog

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oh one other piece i have worked on but not seen either...

articles have been written that "at speed" air pressure builds up in the engine bay causing an engine to run hotter. read articles on filling in the voids on each side of the radiator to build a better bulkhead but it looked rather complicated and i was not ready for all that just yet.

so i made a couple of side pieces to fill the outer grill between the front of the original air deflectors and the outer edge of the grill. what i was trying to cover is the area of blue tape on the regular grill in the next picture.
IMG_0311.jpg

below is a picture of an early test piece for this purpose. you can see i bent it a few times and split it on the one edge. sorry i never took a picture of the finished piece. anyway the bent edge on the left (this one is for the driver side) hooks over the front edge of the original air deflector. the edge with the "A" on it clips over the last strut of the grill. i put a pop rivet just about where that "A" is to hold it in thru that last strut. did it do a good job of blocking air??? i don't know but it sure did a good job of blocking the air ducts up there. i was getting very little air in thru the cool air duct.

so i took it back out and cut where the dotted line is to get rid of that part of the flange. then i slit the other side as well. bent it just a little where the solid black line is. i put it back in and then bent the top back to where it laid on the brace below the air ducts on both sides. i never realized before but those air ducts are not really down to the grill level. putting this bend in is like putting an air scoop below the duct and helps to push a lot more air up in to the duct. you can feel it blowing on your legs now.

first pic below is the trial piece and the second is where i tried to take a picture in the grill. probably will have to blow it up a little to see it better.
fullsizeoutput_1d4.jpgfullsizeoutput_1d5.jpg

hard to see the piece painted black. anyway, i can't say for sure it helps with cooling the car at speed but i can say it helps push more air thru the air ducts.
 
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Drone Dog

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steve
i have been thru your gallery more than a few times. thanks for having that. i was looking for a simpler approach, one that i did not have to pull the radiator. hoping i accomplished that for the parts i have done.

Looking at your picture above reminded me that on the Vette i used to own they had a piece of rubber covering the same area. riveted top and sides, lose at the bottom.

Hmmm, i thought that the wheel arches were considered a low pressure area. would that not help to draw air out of the engine compartment? or does their position work against that?
 
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Drone Dog

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ahhh, gotcha.
have you noticed a large change in your cooling with all the ducting? i ask because i am not sure i see much change. i will take a run and then remove a panel and take a run again. sometimes the car runs cooler without the panel and sometimes it seems to run just as hot... so i wonder if the panels are worth it? right now, in addition to the work above, i have a panel under the radiator over the frame; a panel that runs from the from shroud to the radiator between the frame rails; and a panel that runs from the frame cross member back to about 6" from the oil pan. oh i also extended the factory air deflectors down to about a qtr inch above the tie rod. i still run about 110 over the air temp while driving. have you checked your engine and what it runs? (i also temper mine with the fact the engine still has only about 700 miles since the rebuild)

although after my flush, the last 2 runs seemd to take longer for the engine to reach the 110 above air temp than it did before. not sure the flush was the factor though.

during my flush, i pulled the thermostat out. while out i put it in some hot water to check how well it opened. i noticed it trapped air in it even after it opened. So i drilled an 1/8" hole in it.
plus when i filled the engine back with coolant, i filled the engine first from the thermostat housing. then put in the thermostat, cover and upper hose. Next filled it the rest of the way with coolant in the radiator. big thing i have noticed is that even though i have filled the radiator right up to the neck, it did not blow any extra coolant in to the over flow bottle. not after i shut the engine off and it got up to about 230 on the gauge either. never had that happen before. always got some to blow out. in fact i filled it high so it could find it's own level so to speak. did filling the engine first help get trapped air out?

should one change the coolant at 500 miles when they change the oil on a new engine?
 

steveg

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No large change - but it's hard to tell as it got implemented over a period of time when I overhauled my radiator and rebuilt my engine. A fun project, though.

Cooler air from the fresh air duct due to lack of hot air recirculating forward.

Car runs <190 even on the hottest days. Maybe 100 above ambient. With the rest of the system optimized have never felt the need for an oil cooler. That's a good way of taking a few degrees off.

Changing at 500 mile intervals is too often - if you're concerned about debris, drain it and pour it back in through a strainer, such as a woman's stocking. You can get inexpensive hydrometers and test strips to check the pH.
 
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Drone Dog

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i have been working on my ducting and also added a Spal fan (13") as a pusher.

first the ducting:
i extended the bottom of the original air deflectors down to a point even with the cross brace on those deflectors. then bent an angle on the bottom of them. next i made a bottom shield that lays on the cross brace and covers from under the grill to the radiator. on that straight line it comes out just under the fan i mounted. screwed the pieces together, painted and installed.
IMG_0394.jpgIMG_0395.jpgIMG_0399.jpg



i have wired the fan, right now, to the relay for the driving lights and can turn off and on by that switch for testing.

took a drive today in 90+ degree heat.

first the good news:
even with the electric fan off, you can feel a good pull of air at the grill. it will suck a piece of paper tight. So even though my ducting has not blocked the circulating air 100%, have to believe most air is coming from the grill. that should help with recirculation.

not so good news:
i can't tell the difference in air movement on either side of the radiator with the electric fan on or off. seems to be same amount of air. during my drive at speed or at idle the engine temp did not change with the fan on or off.

Could it be the 6 blade metal fan is controlling the air flow? or that my 8 fin per inch radiator does not benefit from the extra electric help? (my fan is mounted right to the radiator) the only thing that changes the temp at idle is engine speed. speed increases flow at the pump (new water pump from moss) and drops the temp a few degrees from idle temp.

on my ride today, well first of all i let the car warm up until hot sitting in the garage. i was playing with the fan on and off and wanted to see if i could tell anything just sitting there first. took a while but i got the temp to 190*. then shut it down before i took it out. when i started it back up, and after backing out of the driveway, the temp was about 200. it would go down a little as i drove off but not much. i thought for a while i was going to get it back to the 190 mark but as i drove a few more miles at 60mph, the temps did not come down. and when i stopped for an intersection they would rise and not come back down below 195 or so. fan on or fan off did not matter. at one point it had gotten to 200+ and i tried the heater. that dropped it back to about 195 for a while.

So i can't say any of my changes helped, even the new fan. it was over 90* outside and so my 110 over air temp seems to still be holding true. i could live with that but i had hoped the fan would help when i had to stop. it did not.

So i am thinking the only thing that will help is another radiator. (you all probably knew that) i had thought about getting mine recored but i might just buy a new one. my top tank is not really that straight. by that i mean it has ripples and buldges in it. So since a recore and a new radiator look to be about the same price. thinking new radiator and keep this one with the car if someone has to have one with the tags on it. certainly a new one will look better.

i am looking at one from AH Spares (black) and one from Victoria British. anybody with experience with either?

for now i plan to pull the fan back out. no need to leave in there if it is not helping. then add to the new radiator. maybe would be more effective with a core that has more fins per inch.

oh and one last question...
i believe this core was painted when the radiator was done. the fins are all black. would that not hurt the heat transfer from them? anyone else had this? did you clean paint off and if so, how?

Thanks
 

dcarlg

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Is your 6 blade fan a flex fan?
I had similiar overheating with a flex type fan.
Changed to a Texas Cooler with BCS mini shroud which was an effective combination. I added the Spal pusher fan to control temps in stop and go traffic, ie the Woodward Dream Cruise. Works well.
Radiator was recently recored.
Good luck.
Douglas
 
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Drone Dog

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mine is a metal fan.

i think the one common theme i see with most people is a newer cored radiator. while mine has had the core replaced. it is not one of the newer types.
 

Patrick67BJ8

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https://valvechatter.us/?page_id=75

I found this in my files about cooling/heating. The site belongs to Lin Rose. Go to the menu and Big Cooling/heating ducts.
very nice looking duct work. There’s another photo I found that shows a flat duct under the radiator and I’ll try to find that one and post later. I also posted a while back a “white” paper that Geoffrey Healey did on thecengine compartment airflow. Has everyone seen that One?
 
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Drone Dog

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Patrick
i did see that paper somewhere and the valve chatter article above. i have hit all of these check points plus the sleeved thermostat. well all but one....the radiator.... funny, i read about the duct system, and it makes sense, but i have never seen where anyone found that was enough. everyone who did the duct work also mentions they did a new radiator or recored one. So i think that is going to be the only answer for where i live.


Steve
a while back from another thread i was told to check my gauge with a meat thermometer. i had used a IR gun until then. the thermometer in the top of the radiator showed my gauge was pretty darn close at least thru 175 or so degrees. So i assume my gauge is fine. however, it does do this funny thing at about 212*. sometimes when i shut the engine off and the gauge climbs up over 212, around that number the needle will do this bounce and wiggle for about a second or so and then settle back down. Not sure what that is. come to think of it, i am not sure i have seen it happen lately.
 
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Drone Dog

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absolutely. at my age reminders are never a bad thing.... and simplest things first are the best way to go.
thanks
 

Rob Glasgow

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Steve, my temp gauge was like yours. It registered 15 degrees hot. I finally decided to fix it by removing the chrome bezel and glass, pulling the needle off with small needle nose plies and resetting it. On cooler days, the gauge now reads 165 which is the thermostat setting for my Summer t-stat. I used to change it over to a 190 t-stat when I lived where it got colder in the winter, but where I live now, there's not much difference between summer and winter so I usually just leave the 165 in place.
 
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steveg

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... I finally decided to fix it by removing the chrome bezel and glass, pulling the needle off with small needle nose plies and resetting it. ...

I did exactly that. I'm lucky enough to have inherited a set of miniature side cutters which allowed me to pull the needle straight off to the front, then press it back on in the corrected position with my thumb. The needle itself is robust enough to withstand this handling.
 
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