Replacement RH vent duct for a '65

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SBurney
Posts: 66
Joined: Tue May 16, 2017 4:04 pm

Replacement RH vent duct for a '65

Post by SBurney » Tue Oct 03, 2017 10:22 am

While the dash is out of the car I’ve been tackling all of the other broken stuff, too. One of them is the right side fresh air vent that was originally rubber, but after 50 years has turned to dust. After reading other posts on the topic, I decided to replace it with a metal duct. After quite a bit of trial and error I decided to post what worked to maybe save someone else the trouble. By the way, my car is a ’65 with A/C.

First of all, the dash has to be out, as well as the passenger seat and preferably the rear seat to give you some room to work. The next step is to remove the heater box. It probably isn’t 100% necessary, but it’s not too difficult and it makes the next steps much easier. I won’t detail the removal process because another poster has done an excellent job of it (search for ‘Heater Core Removal, with photos…’), but the short version is to disconnect the heater hoses from the engine side, remove the nuts from the studs above and below the heater hoses, and remove the 4 nuts that hold the fan box to the heater box-they’re behind the recirc air door and are best accessed by applying vacuum to the actuator that’s on top of the heater box. You can detach the fresh air vent cable, but since it’s only held on with 4 screws I found it easier to remove the whole vent piece and set it out of the way. After that the heater box can be removed from the car.

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In this photo, the heater core has also been removed since I had to replace it, too.

The next step is to remove the flange that holds the top of the duct to the vent opening in the car. There are 4 screws, and they’re not equidistant so that it can only be installed one way. There is a notch in the flange, which when it’s installed faces the left (it's hard to see the notch with all of the gunk on it, but it's there).

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Once it’s removed you will see that the rubber is (was) held on with staples, and there’s also a lot of sealant on the surface that mates to the car. Remove the staples, peel off what’s left of the rubber, and scrape off the sealant. I may have gone a little extreme, but I then took a wire brush to get all of the old stuff off, then primed and painted the flange.

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Apply some silicone sealant to the flange where it mates to the car and reinstall it, making sure to face the notch toward the driver’s side.

Reinstall the heater box.

If you look closely, you can see that the duct won’t be a straight cylinder, but that the heater box is slanted, so the duct will have to be slanted as well. The distance between the base of the heater box and the base of the mounting plate is 2” on the short (left) side and 3 1/8” on the long (right) side. If you take a piece of sheet metal and cut a straight line from one end to the other, it won’t work because the ends that meet will be different heights. The way to do it is to have both ends at the low measurement and the middle at the high measurement. This is the money shot of the whole article, it's what the new duct will look like after it's cut out. (The ends are curled under because I had already rolled it in to a cylinder before I took the photo.)

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The circumference of the flange is a little bit bigger than the circumference of the heater box opening, but they’re close enough that it works. The number is about 19”, but I used 20” to have a little bit of overlap. I used roof flashing that I picked up at Home Depot for $10 for a 10 foot roll. Measure out and cut off a piece 20” long. Measure up 2” at each end, and 3 1/8” in the middle. Use a straight edge to connect each end mark to the middle mark and cut along that line. Instead of a sharp point, I kind of rounded off the top of the cut. When you’re done it should look like the piece in the photo above. When you wrap it into a circle it will look like a slanted cylinder, which is what we want.

The vacuum router for the door locks is hanging right in front of where the duct goes. It’s held on by 2 screws and the job is easier if you get it out of the way.

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The tricky part is to get the duct attached. I tried it a couple of ways, but here’s the one that worked: starting at the right side, feed the flattened (but still kind of curved) sheet metal down the side of the heater box and flange, work the back side around to the left, and wrap the front side around to meet it. The seam will be where the notch is, where the flange and the heater box are the closest together, facing the driver’s side. You may have to reach one hand up through the vent opening to help it make the curve around the back side.

Next, take 2-6” hose clamps and open them up. Feed the end without the screw of one of them around the duct (make sure the screw head will be facing you), reattach the ends and snug it up, then do the same with the other clamp. Others have suggested using duct tape on it, but 1) the clamps and the seam seemed tight, 2) I think I would have needed 2 extra hands to be able to hold the duct together and tape it before the clamps were installed, and 3) the seam is only 2” tall, and the area would be difficult to get to with the tape.

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Reattach the lock router, reattach the vent, and move on to your next under-dash project.

{Here are some other shots so you can kind of see what it looks like assembled, but it WON'T go in the car like this-I tried. If the duct is mounted on either the heater box or the flange there isn't enough room to maneuver the heater box into place.}


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Steve Burney
1965 Special Landau, originally purchased by my Grandmother. The only car she ever bought that
she thought was worth what she paid for it.
VTCI #12702
Thunderbird Registry #64708

vince
Posts: 482
Joined: Fri Jul 16, 2004 12:08 pm
Location: St. Louis, MO

Re: Replacement RH vent duct for a '65

Post by vince » Sat Oct 07, 2017 10:47 am

Great article. Thanks
'66 Convertible, 428, in progress

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paulr
Posts: 1023
Joined: Mon Nov 05, 2012 12:03 pm
Location: Seattle

Re: Replacement RH vent duct for a '65

Post by paulr » Sat Nov 04, 2017 2:43 pm

Great work, Steve. I neglected to tape my sheet metal seam with any tape when I did this a few years back, and took a scolding from a member who warned that my work would suffer from air leakage due to the "mistake". Can't say that has been any problem at all for any passengers who've made use of the vent. Also, I was informed this (completely invisible) repair method was not concours.
I have a word for that! :badgrin:

I always appreciate your well-photographed and documented restorations.
Paul
VTCI 12014
Registry 45122
'64 Landau
"Beer, now there's a temporary solution!" ~Homer Simpson

SBurney
Posts: 66
Joined: Tue May 16, 2017 4:04 pm

Re: Replacement RH vent duct for a '65

Post by SBurney » Sat Nov 18, 2017 8:12 am

Thank you for the compliment, Paul.

I read those posts about concours correctness and draftiness, but then decided that these cars were built as quickly as possible by hourly workers, not proud works of art created by craftsmen, so there is probably room for improvement in some areas and this is one of them. It’s my understanding that the concours judges don’t dig into the cars, so out of sight is no penalty, true? I did worry a little about an unwanted draft at the seam, but there really isn’t much of a gap between the clamps and I think I have the overlap facing the front of the car so any leakage would be directed away from the passenger and dissipate under the dash anyway. If anyone does complain, I’ll just tell them it’s supposed to be like that.
Steve Burney
1965 Special Landau, originally purchased by my Grandmother. The only car she ever bought that
she thought was worth what she paid for it.
VTCI #12702
Thunderbird Registry #64708

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