| Hot Air Pipe [message #81137] |
Mon, 19 April 2010 21:37  |
Bob Horton
Messages: 81
Registered: December 2005
Location: Brandon, Manitoba, Canada
Karma: 0
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I notice that the item described as "a hot air pipe" is missing from my air cleaner assembly. Is this something that many have removed over the years or should I be concerned. I notice that the vacuum line to the air cleaner assembly is also conspicuous by its absence.
Bob Horton
Brandon, Manitoba
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| Re: Hot Air Pipe [message #81152 is a reply to message #81137] |
Mon, 19 April 2010 23:47  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| Bob Horton wrote on Mon, 19 April 2010 21:37 |
I notice that the item described as "a hot air pipe" is missing from my air cleaner assembly. Is this something that many have removed over the years or should I be concerned. I notice that the vacuum line to the air cleaner assembly is also conspicuous by its absence.
Bob Horton
Brandon, Manitoba
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If you are talking about that 2" or so piece of flexible pipe between the air cleaner and the exhaust manifold, you can get one at most auto parts stores. If the vacuum line is not connected then that pipe is not of any use. The valve in the air cleaner requires vacuum to open all use the hot air coming in that tube.
That whole assembly is used to prevent carburetor icing under certain temperature / humidity conditions. I do not even have one on my coach and I know a lot of GMCers also do not have one.
It is up to you if you want to bother with it.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Hot Air Pipe [message #81269 is a reply to message #81137] |
Tue, 20 April 2010 22:35 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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It also does one more thing in that it 'levels the playing field' for the the carb mixture. Since in pre EFI engines you have a fixed mixture but the engine would like it slightly richer when cold, leaner when warm outside, by blending the air to always be at 115 deg at the carb they could set the mixture during normal (light) driving to a constant standard and thereby tune to the leaner side of the equation for emissions still with good drivability. When you go to WOT the vac falls and it opens to full cold outside air so it is not a robber of performance. That's if it is all intact and still functioning. I like it have have mine in OEM config. Nest step is to add a second snorkel that only opens when vac drops. GM used this dual setup on most hi perf apps with the heat stove pipe only on the the Thermac side. I think the stock single snorkel is somwhat restrictive but was for noise specs. Induction noise on the open Qjet 455 is pretty loud.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Hot Air Pipe [message #81415 is a reply to message #81298] |
Thu, 22 April 2010 01:23 |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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The hot air pipe will not do much good unless you also have the sheet metal stove around the exhaust manifold that the lower end of that tube connects to.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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