Cars

Installing a Vintage Air Heater with a Stewart-Warner 781 Heater Part 2

When we left you last (Installing a Vintage Air Heater with a Stewart-Warner 781 Heater) we had gutted our vintage Stewart-Warner 781 South Wind heater and converted it to a hot air distribution box and a great looking control panel for our Vintage Air Gen II Heater (PN 506101) with defrost unit. The Vintage Air unit would be mounted up behind the original glovebox while the Stewart-Warner unit would mount the controls and distribute some of the hot air.

The Vintage Air heater is a very compact unit with the ability to distribute a large quantity of hot air to the defroster, direct to the floor or blend hot air distribution to both defroster and floor, much like the heater in your modern car. With three fan settings the unit has the ability to provide warmth on a cool day in an open car.

We began this part of the project by disconnecting the battery. Mounting the unit involves some basic fabrication skills. The Vintage Air unit has a mounting plate with four holes attached to the unit. You will notice there is a thin layer of foam rubber between that plate and the actual heater, which prevents vibration being transferred to the car. To mount the unit up high on the inside of the firewall we welded two studs to the inside of the firewall. We did this rather than have bolts showing on the firewall. With these two studs in place we set about fabricating a lower bracket to mount to the firewall and to the two lower bolt holes in the heater mounting plate. The mounts proved to be very sturdy, mounting the heater securely.

After mounting the unit it was time to cut two holes in the firewall using a 1-1/8-inch hole saw. After just a little work with a file we were able to install the two heater hose grommets supplied with the heater. Next we drilled a hole below the hoses and installed a grommet for the main power wire on the heater. We have a grommet assortment we picked up at Harbor Freight and due to the lower shop temperatures and the fact that the assortment is several years old the grommet was a bit stiff. Luckily we have a grommet softening device in our shop (we have also heard some people refer to this tool as a microwave). We took a cap from a spray can, added a bit of water, and dropped the grommet into the water. We then put the cap and water inside the grommet softening device for 40 seconds and out came one very soft grommet. Be careful because the small amount of water is literally boiling hot and that hot water heated the grommet without damaging the rubber. This made installing the grommet much easier.

The next big piece of the puzzle was the wiring. As we mentioned earlier we picked up the main power source right off the firewall-mounted starter solenoid. The Vintage Air wiring includes a circuit breaker so we mounted that next to the solenoid. Keeping the circuit breaker close to the solenoid minimizes the amount of unprotected wire, in our case just 5 inches of wire. Note there is a power in and an accessory side to the circuit breaker and it is marked on the unit. Basically the copper stud is power in, while the silver stud goes to the accessory, in this case the heater.

Following the wiring instructions and schematic (I know, crazy as it seems, reading the instructions actually helps) we routed our wires down to our Stewart-Warner heater box while another set of wires were routed to the passenger side kick panel where it would eventually plug into the heater control valve potentiometer. While the Vintage Air heater is largely plug-and-play, we decided to modify the harness just a bit. We thought it would be best if all wiring could be unplugged outside of our Stewart-Warner heater. This involved cutting and adding a bit of wire to the heater control valve servo harness so the plug would be outside of the Stewart-Warner heater. We used solder and shrink tubing to modify the harness. If you used the control panel supplied in the Vintage Air heater kit you would not have to modify the harness.

Last but not least we had to connect 5/8-inch heater hose from our flathead engine to the heater. The heater comes with some neat 90-degree fittings that seal like an A/C fitting with O-rings. These fittings enable you to angle the hoses nicely. We also employed a molded 90-degree heater hose (Gates PN 28460) to direct the lower hose directly toward the lower hole and grommet in the firewall. We installed the heater control valve in one side of the molded hose and plugged in the Vintage Air wire plug. That completed our installation. Now here is the cool part. By keeping the hoses up tight to the cowl we were able to hide the hoses inside the kick panel, making for a very clean installation and we only sacrificed 1/2 inch of legroom at the firewall.

We did not make our final connections to the engine as we plan on changing the heads and purchasing new Bob Drake water pumps with a heater port. However, we did connect the battery and run the heater through its paces and we can report that the volume of air is impressive. We must admit the louvered South Wind heater may have too many openings aimed away from the passengers. Automotive climate control relies on directing the air onto the occupants. A cure for this would be just use the Stewart-Warner heater as a deco-piece with heater controls and route the hoses from the Vintage Air heater under the dash where they would blow directly on the driver and passenger. Having said all that we feel certain this Vintage Air heater will help keep passengers warm on a cool day and possibly help keep an engine cool on a hot day, after all we are running a Flathead. SRM

For the Jun. ’17 issue, we modified this Stewart-Warner South Wind heater to hold the controls for a Vintage Air heater and to act as a hot air delivery box, hence the louvers.
The Vintage Air heater is a very compact unit that should fit up under the dashboard of most early hot rods. We positioned our heater up behind the glovebox in our 1936 Ford Phaeton.
One great thing about Vintage Air products is they are always complete, with everything from grommets to hose clamps and bolts.
Before finding a good location for the heater be sure to install the two 90-degree fittings on the unit, as you must allow room for these connections.
After disconnecting the battery our next step was to remove the old glovebox. The new glovebox will have a few inches less depth and we will fabricate it out of sheetmetal rather than cardboard.
Looking up at the firewall from inside the car you can see the two holes we drilled. The heater has a mounting plate built in so these hole correspond the location of the top mounting plate holes.
We didn’t want bolts showing on the engine side of the firewall so we fabricated four studs by cutting the heads off the 1/4-20 bolts supplied with the kit. The double-nuts will help us thread the studs in the firewall.
We didn’t want bolts showing on the engine side of the firewall so we fabricated four studs by cutting the heads off the 1/4-20 bolts supplied with the kit. The double-nuts will help us thread the studs in the firewall.
We TIG-welded the studs using the slight protrusion of the stud as filler metal. A quick hit with a grinding disc and the firewall was smooth once more.
Now we had two studs on the inside of the firewall. We hung the heater from these studs as the initial location while we fabricated the lower mounting bracket.
Using an angle finder we measured the angle of the firewall. These are really handy tools; we picked this one up at Harbor Freight years ago.
After cutting a piece of 16-GA sheetmetal we laid out the basic pattern for the lower bracket. We drilled two 9/32-inch holes in the bracket to slip over the 1/4-inch studs.
Using the same angle finder we went over to our metal brake and bent the appropriate angle on the brackets.
Next we cut a piece of 1/8×1 flat stock and drilled two 9/32 holes to match the hole locations on the back of the Vintage Air heater. The piece is clamped in place for welding.
After welding the pieces together it was treated to a coat of Summit Racing primer and chassis black paint.
After installing our lower bracket the unit was rock solid. You may notice we couldn’t resist drilling some “speed holes” in the face of the bracket even though you must lie on the floor to see them.
Next we began routing the air duct hose from the Vintage Air heater to our Stewart-Warner South Wind heater. We are always amazed at the flexibility of this hose.
Since we were mounting all of the Vintage Air control switches inside our Stewart-Warner South Wind heater box we decided to extend the heater control valve (temperature control) harness. A shrink wrap assortment from Harbor Freight combines with basic electrical tools to get the job done.
Here is the completed harness, extended so the plug will be located outside our Stewart-Warner heater. This enables us to simply unplug the Stewart-Warner heater without removing the back panel.
Now it was time to route the heater hose and source the electrical connection for our Vintage Air heater. We drilled two 1-1/8-inch holes in the firewall and with just a little file work the Vintage Air grommets were installed. Note the small grommet below for the electrical power.
Our Harbor Freight grommet assortment is several years old and it is pretty cold in the shop this time of year, making it difficult to install the hard grommet.
The solution to pesky hard grommets happens to be the same place you re-heat your coffee. Yes, the shop microwave oven will come into play.
Since we wanted to heat the rubber grommet as opposed to melting it, we took a spray can cap, added a little water, dropped in two grommets, and “nuked” it for 40 seconds. That was long enough to boil the water and soften the grommets. Of course be careful because the water is literally boiling hot.
We decided to use a formed 90-degree heater hose for our lower hose connection. This made a very clean, straight shot toward our firewall holes. The Gates 2460 hose has one 4- and one 5-inch leg.
We installed the heater control valve into the Gates-formed hose. Be certain the arrow is pointed in the proper direction (toward the heater) and that you can access the electrical plug.
Here you can see the two heater hoses connected and feeding out to our Flathead motor. The electrical plug from the Vintage Air heater is also connected.
Now here’s the cool part of this heater install. By keeping everything as close to the cowl panel as possible we are able to completely hide the heater hoses connections with our kick panel.
On the firewall side everything is neat and clean. The Vintage Air circuit breaker receives power from the positive side of the starter solenoid and that feeds inside the unit.

We connected the battery and tested the Vintage Air heater. When the heater door opens it pumps serious air, or the switch will close the door and direct the air to the Stewart-Warner heater box. It all works and runs smooth as silk.
With the heater install complete we must be honest. The louvered Stewart-Warner heater probably has too many opening so you don’t feal a real directed blast of hot air, rather it just swirls around (the bottom of the heater is open too) but at the end of the day we still have one very cool heater.
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Thanks !

Thanks for sharing this, you are awesome !

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