Hi all, trying to get my car all sorted out and was wondering if anyone knows what this duct tape is covering up? There is one on the passenger side and another on the drivers side under the car near the engine. Is this something to do with the heating system? The heating system doesn't work and I know I will need to add parts like hoses and flappers, the car does have heat exchangers.Click to view attachment Click to view attachment

Yep.. that’s the air from the fan that goes to the heat exchangers

Yep, missing both S pipes, J pipes and probably the heat control flaps. Not good for engine and alternator cooling blocked up with duct tape.

Should I remove the duct tape and put cheese cloth instead?

http://www.914world.com/bbs2/index.php?showtopic=247782

Your missing some pieces. I would be more inclined to have them uncovered if I didn’t have the flappers and the other stuff that goes with these...assuming that you are on the way to getting the correct components installed.

I used foil tape here as a quick fix one time. You are losing cooling air out of them otherwise. Foil tape is pretty tough stuff.

I don't have HE's on my '73 in AZ as I don't need heat there! I covered those two opening with tin- figured the air would just be going out in air flow under the car - with them covered, I assume that means more, not less air for the rest of the engine including the oil cooler and alternator.

Here's what's supposed to be there, the ducts that send fan air into the heat exchangers that goes for cabin heat. When he flappers are closed (no cabin heat, the hot air in directed down under the car.

Click to view attachment

That looks like an AA picture with the wrong J tubes. Everything else is the 70-74 style parts. The J tubes pictured are75-76 square ones.
It has been shown that it is better to leave them open if you do not have the heater parts to hook up. Blocking them creates air flow disruption to the engine.
They are supposed to blow some air thru the heat exchangers atall times. When the heat is not on the air blows thru the heat exchangers and out the flapper valves to prevent a high temperature build up.
Just remove the tape and you are fine.
You are also missing the warm air guides that are the plates that go between the engine block and heat exchangers. The one on the drivers side helps with the thermostat operation by blocking under car air from mixing with the warm engine air.
If you want heat I have the S branches, J tubes, flappers and related parts.
Did they block the large holes in the cylinder tin for the J tubes ? If not the engine fan will suck hot air from below which is not good.
How about a top picture of the engine. I bet other parts are missing.
Bruce

Correct me if I am wrong, but that is the bottom of the fan shroud that is supposed to have 2 small metal flaps, one on each side. It has nothing to do with the heating from the heat exchangers. No ducting gets attached there.

Hi Bruce, yes I am missing the top parts as well. It seems like a simple fix but not all is clear on how all the parts go together. It seems that if I buy all the parts and do a dry fit then only a few questions should remain (like how to hook up the flapper but I can see the cable in one of the earlier pics for that. The picture from AA is very helpful to visualize the parts. Do you have a website or should I email you to figure out all the parts I need to order? Everyone has been so helpful. Here is a picture of the top side.
Click to view attachment

I would leave them uncovered. I recall reading that Jake Raby found that blocking them causes turbulence inside the fan shroud, which negatively impacts cooling.
The fan shroud was designed for air to exit there. Let the air exit as designed.



Ducting does get attached there. There's a Y branch piece that connects from the fan shroud to the heat exchanger. The branch piece also connects to the vertical J-tube which brings the air from the electric blower in the engine compartment to the heat exchanger.

I'll do an experiment to test what Raby says. I'll take the covers I made off the outlets and see if it affects oil temp.

O.K. The little faps normally accommodate airflow from the main fan into the heating system. If they are left open to the environment they will allow more heat out of the squirrel cage housing, leaving less pressure to cool cylinders and heads.

But that isn’t how it was designed. The design included back pressure from the heating system.
I am reminded of the never dying myth with water cooled engines that slower flow through the radiator is better because it gives more time for the water to cool. Nope. But that is another topic. As is the fact that a centrifugal pump uses the least energy when valves completely block outflow.

The effect would be on head temps since the air blows over the heads and cylinders. Not necessarily on oil temps.
Head temps and oil temps are not necessarily always connected.



You're saying that it wasn't designed for air to flow out of the fan shroud all the time? Backpressure or no, air is still always leaving the fan shroud at those ports. If the HE's are connected the air travels through them and exits to the atmosphere anyway through the flapper valves if the heat isn't on, or into the cabin if the heat is on. There's always air moving through that system. Blocking the air completely will have negative results. But without a 4 channel head temp gauge to monitor all 4 head temps, you'd probably never know.
Do what you want, but if it were my car I'd take Jake's advice and leave them open.

At idle there is a lot less airflow. Cabin heat and defrosters suffer during these times. The electric fan supplies air to make up for this loss. Without the flaps, some of the air would enter the fan housing and not into the cabin. These are check valves for the air flow at idle speeds. Above idle, there is a lot more air and this forces the flaps open

You have a number of open holes in your engine tin. You Need to fill those holes with the appropriate parts.

Tom,
I was wrong. Obviously you don't have the two S shaped pieces for the heat exchangers, like the one I showed you on my desk.

You can buy the flaps from 914rubber as they recently started producing them.

The doors are uneeded if you don't plan on using the aux fan.