I think the one I saw he was using the fan to draw air out of the engine compartment and using the side vent as an exit.

On the drivers side, that can is the "carbon canister" which is where the gas tank vents to and then a hose runs to the carb (with stock setup) to burn those gases. It has charcoal in it basically.

Since we don't need a front license plate here in AZ, I'm planning to use a '74 front bumper and make an air duct that runs from behind the license plate area and forces air into the radiator.

 

Re: the fender vents, for a race car, that's stripped of everything, that would probably work! No fender liners, no a-arm dust covers, no nothing!

Thanks for the info on the carbon canister! I swore, the lines ran from the brake distribution valve, but I was probably halucinating after a long night under the car. Keep us posted on the air duct. I think someone here had that? I coulda swore (maybe not?) that I saw a center section of the grill opening, made up into a huge scoop.

 

Yep.. I got the idea from someone here. I think they had a screen over the opening in the bumper (mounted from behind) instead of the grill. Looked really tough - like something off of a road road car.

 

I pulled my carpet and put in dynamat type insulation and then new carpet an mine was still hot as "billy goat hell" inside. It's handy in the winter though. I bet wraping the headers is the best idea, it seems to only make sense.
johnny Y

 

Hi Johnny, we too, thought the headers were the main problem. There is more than that going on. If your interested, go back a few pages and see what we came up with.

Regis

 

I want to get more air into the cabin. How about running a duct from in front of the radiator and into the plenum where the heater fan is?

 

That's not a bad idea at all! I like it. Where does the whole system get it's air from now?

 

Comes from the passenger side lower windshield area, essentially from the outside anyway so a line from the front of the car wouldn't be needed.

How about same air supply but higher volume. Replace the fan squirrel cage with a C4 one like is usually done BUT replace the motor with one that can go 10,000 rpm instead of 5,000 rpm on an A/C car the heat issue may be solved.

 

Wow, 10K RPM! That's doable and on most A/C cars, I'd say, that the heat problem isn't as bad, because you have the A/C system, doing battle against the heat from the firewall, so I'm not sure if the heat issue, would be solved and I'll say this, because the A/C system, would have a lot less work to do, if we extracted the heat, as we're planning to do, from the engine compartment.

If we fixed the heat issue, I can see many benefits.

1. Less work for the A/C system to do (if you have one).

2. The heat in the passenger compartment is reduced to ambient temperatures or slightly higher (acceptable).

3. Longer life for underhood components and accessories.

4. Cold air, full time for the intake snorkels, versus, just when the cowl hood is opened up.

5. Increased performance, from reduced underhood tempuratures.

6. Elimination of heat soak when vehicle is standing still (convection of heat through hood vents).

Update: We test this afternoon at 1 PM PST. Will report on results at 3:30 PM, PST.

 

Thank you so much for this great piece of information!!!

 

I have my fingers crossed for a good result today. We have followed a reasonable and well thought out process to get where we are today. I can hardly imagine where to go from here if this proves to be unsuccessful.

Regis, I am so glad you have taken the ball and run with it. Not many people would go to the lengths you are going through to find an answer to this (very old) problem. Most of us, myself included, have discussed this problem at length but few have dived in and decided to do something about it beyond the usual fix actions which have proven to be only marginally successful. Your efforts on this are simply outstanding.

Thank you,
John

 

Hi Minitech, I appreciate your thinking, but my reasoning was that the windshield area air is hotter than what could be ducted into the plenum from the front and you could be "ramming" it in instead of sucking as now. I fully understand F22's efforts and hope for a good result, but from research believe that GM fitted the rubber seal around the windshield end of the hood to help keep hot air away from the cabin fan intake. So F22 mod will probably result in hotter air being available to be picked up by the cabin fan so another source of air for this might be desirable? I desperately need to get more cool air into the foot-well area. My coupe is an air car with air deleted and I mean 95% of it is missing, my budget wont stretch to a refit or vintage air system and being an air car there are no foot-well vents fitted.
I have just opened up the rear vents behind the seats because these are blanked off in an air car, just another thought I had would be that it would be easy to mount a fan there to blow air out of the cabin. Pushing air out of course will make it easier to get air in.

 

John, thanks for the kudos! I took this on and decided to see if we could fix this, once and for all. I appreciate the kind thoughts and we have T minus 1 hour and 17 minutes to test!

 

My car had AC but it's long gone too. HG, you bring up a good point about the cabin air pickup. That is a factor and you're right, we need more cool air into the foot well area. You also bring up an interesting point about the input at the base of the windshield and here's what I'm going to do today during testing. At the hour mark, I will open up the foot vent on the driver's side and take a temp reading from inside the vent, with the thermocouple on the BK Multimeter as well as using my hand to 'feel' what the temp is as well.

That's an important point and not one to be ignored and I fully appreciate your additonal thoughts on this. There is weak air flow to begin with, without the fan (as we all know) so I'm not sure how much heat can or will be pumped in by the vent mod, diverting heat to a low pressure area.

At speed, it might just blow, right on up and over, with little effect, or not. I will incorporate this into today's testing in just over an hour and report the results.

I will be back by 3:30 PM PST and am going to do a write-up, to let you guys know how the testing went.

Thanks!


Regis

 

I'm optimistically waiting your report there F22

 

Left at 12:45, topped off the tank and here are the results. It was mixed, but found new things too. First, it did help. The brake pedal and hood release, didn't get nearly as hot as last time. In my excitement about the grills, I overlooked plugging a hole where the tach cable came through, so got to fix that. The hood grills work good. At a stop, you can feel the fan pumping the air out the rear portion of the grill.

Still want to do the yarn test and I may just do that tommorow to see how they behave, while the vehicle is moving. The temp under the dash is still about 120 to 123 degrees, but while I was stopped at the one hour mark, looking under the dash, I found something, that really surprised me. I glanced at the steering column at the point, where it attaches to the floorboard and it's a semi-circular metal plate, that reinforces the area around the column.

That plate is 143 degrees!!! I touched the steering column and it was blazing hot! Still had the hood open, so I started shooting the steering box with the IR gun and it was 200 degrees! It's only inches from the number one exhaust header! The whole outside column was 180 to 190 degrees, lessening as it moved to the firewall!

This is definitely a multi-faceted problem. I'm now thinking of how to defeat that steering column problem. Will post pics in about thirty minutes.

 

I stopped for a beer on the way home (ok, maybe two!) a tasty IPA and a really nice Hef.

UPDATE: The heat soak is gone! The car was totally cool, by the time I got out. The hood grills, really helped evacuate the heat while the car was sitting for 30-45 minutes. The trans tunnel only measured 95 degrees instead of a 110! Very good.

OK, but we still got heat problems and as mentioned, it's a multi-faceted problem, with different contributors. Allow me to share some photo's. Just because we didn't get the spectacular results, doesn't mean we quit trying. The Steering Column tempurature was a huge discovery!!!

Who would've thought, that plate on the inside supporting the column, with the firewall would be 143 degrees!!! That's amazing! You have a 143 degree heat source, right smack dab, in the middle of the firewall! Like it ain't going to migrate and move elsewhere? Sure it is! That really surprised me and I'm glad I found it. I thought it was the overall firewall and in some way, it might just be.

I'm going to ask some of you to shoot that plate directly on your next long drive and verify the results.

OK, some pics are in order.

Steering box Temp (and I took it multiple times.) 202 degrees!



Steering column, just about a half foot to a foot up from the Steering Box



Back side of Wiper Area, where the supposed 'cool air' is going to come in through the vents. PS: I had Dynamat covering up the driver's side Floor vent! So I wasn't able to shoot that temp! The passenger side, has a plate, where the MSD box is mounted. Got to fix that and test.



Hood Grill Action. Note strip of paper is lifted by the air pushing out from the radiator fan. Next, test with strips.




Next steps:

1. Eliminate the Steering Column Heat, by shielding the Steering Column from the Header

2. Plug the holes in the firewall (doh!)

3. Retest and keep going.

Thank you all, for following. I will take tommorow afternoon off and start working on the Steering Column aspect. I have the material, both Kapton and 1/8" thick fiberglass and I'm going to make up a multilayer sandwich to deflect the heat.

And if this doesn't fix it, we're going to Phase II, which is the Ram-Air through the fenderwells.

Regis

 

Back at the Shop and I'm a Shootin' fool, with the IR gun. Paid really close attention to the driver's side floorboard and the steering column plate IS the hottest thing under there! I shot all around and everything else is ten, twenty, thirty degrees cooler. I learned something new and knowing it, is a shot at mitigating it.

The hood grills are doing a great job at dumping the heat out of the stationary vehicle, so at least that was a success! Temp coming out is 125 degrees versus 105 degrees on the surrounding area. Tonight, I'm making up a multilayer heat shield for the steering column. Oh, and by the way, the measured temp of the non-functioning AC plenum was 135 degrees at the bottom, so you AC guys, that's what your AC system is going to battle with.

 

How hilarious! Took a really close look at steering column - header relationship, space wise to consider the placement of a shield and my eye took in the space between the steering box and the bend in the typical exhaust and I qouted inches earlier.

My little steel ruler says 3/4 inch, just eyeballing it. Sooo, you have the number one exhaust header at bend, adding to action, less than double that. You barbecue steaks on less heat, than is output from two header bends , right out of the head. I measured 450 degree minimum, saw 500 plus at times. That's the Broil setting on your typical oven. And with adjustable racks, but 3/4" for the steering box?

Pull open the broiler and I'd bet the finger wouldn't stay long at that distance. The gear box is very heavy cast iron, the perfect long term heat soak candidate IMHO. Just thinking and looking.

 

Nice work. Thanks for the diligence. I check out this thread everyday. I do appreciate all of your effort.