C2 Defroster duct to heater box space

[Ed S.]

A post on this forum (in a tread relating to non AC C2 heater boxes - sorry, I can't find the thread) stated that there should be a space between the top of the heater box and the defroster duct - they are not connected. The reason was that if there was no space the forced air made a resonate sound that was annoying. Is this correct? If yes, what should the approximate distance between the two components (defroster duct and heater box) be? This "space" is not mentioned in the Judging guide.

[Gary B.]

Ed,

I’m pretty certain there is a posting in the archives by John Hinckley that talks about that gap and the exact reason you mention.

Gary

[Don H.]

here's an old thread on the subject, but I don't see any comment on the size of the gap.. JH comments in post 19
https://www.forums.ncrs.org/forum/te...in#post1129819

this is from my Jan 64 coupe
IMG_3932.jpg

[Ed S.]

Gary, Don..... thanks for confirming the "space" between the ducts. And thank you Don for crawling up under your dash - upside down - and taking that pic. The space I had was about the same as yours - around 1/2 to 3/4 of an inch.

I have my heater box out - discovered I have an original, correctly dated Harrison heater core. Will be searching for a radiator shop near me to refurbish it and will also be purchasing a rebuild kit (gaskets, etc) from one of the vendors - I've already decided which one.

Thanks again to all.

[Harry S.]

Ed, I’ve had my inner box out of my 63 about 3 times. Probably 22 years ago. From my fading memory I do not recall any way to make an adjustment. Just four studs on the right and one on the left. All round holes with nuts.

if you discover a way to make the adjustment, please post it.

Thanks

[Ed S.]

From what I understand the space is necessary to mitigate the forced air from resonating or making the duct work resonate. Apparently the fast moving warm air rises up to the vents an does what it is supposed to do even with the spaces. Good enough for me - I don't think there is any kind of adjustment that can be made to alter the size of the space. If I discover one during reassembly I will definitely post the info.