"Gary,
Saw your post on GMCnet. Can you elaborate on what you did
exactly? I've seen the site yu refer to, but don't really understand
the Max Air door mod. Have you noticed any difference? I also have
a 1973 260."
Eric the "Max Air" door modification provides extra outlets at the
floor below the dash.
In the stock 1973 configuration a horizontal slot about 2" X 20" at
the floor is used as a recirculating air inlet to the heater box.
I divided that opening so that only about 2" X 5" is used to provide
recirculating air to the heater box. The recirc opening has been
reduced to match and the recirc door cut down so that when
opened it does not restrict the fresh air inlet.
I cut a new door opening in the heater box behind the heater core.
The pivot for this new door aligns with and is attached to that of the
factory recirc door. Therefore when the recirc door is opened by the
vacumn pot the max air door also opens.
On the floor a made a small extention for the max air vent with a
couple of outlets from the auto wreckers so that the air comes
into the cabin rather than simply return into the heater through
the recirc opening.
As to how it works it is far to soon to tell. Only finished putting it
back together last night and still have lots of work to do.
Regards
Gary Zingle
1973 GMC 26 foot
Saw your post on GMCnet. Can you elaborate on what you did
exactly? I've seen the site yu refer to, but don't really understand
the Max Air door mod. Have you noticed any difference? I also have
a 1973 260."
Eric the "Max Air" door modification provides extra outlets at the
floor below the dash.
In the stock 1973 configuration a horizontal slot about 2" X 20" at
the floor is used as a recirculating air inlet to the heater box.
I divided that opening so that only about 2" X 5" is used to provide
recirculating air to the heater box. The recirc opening has been
reduced to match and the recirc door cut down so that when
opened it does not restrict the fresh air inlet.
I cut a new door opening in the heater box behind the heater core.
The pivot for this new door aligns with and is attached to that of the
factory recirc door. Therefore when the recirc door is opened by the
vacumn pot the max air door also opens.
On the floor a made a small extention for the max air vent with a
couple of outlets from the auto wreckers so that the air comes
into the cabin rather than simply return into the heater through
the recirc opening.
As to how it works it is far to soon to tell. Only finished putting it
back together last night and still have lots of work to do.
Regards
Gary Zingle
1973 GMC 26 foot
