Second Charcoal Canister Needed?

T

Tom Katzenberger

Well-known member
Jun 26, 2019
795
287
63
Good evening all,

I have a 1977 23' Birchaven with 2 Charcoal Canisters. Is it worthwhile to keep 2 canisters or only necessary to have one?

Take care,
Tom K.
--
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D.
 
One of those canisters traps gasoline tank expansion fumes, and routes it
to the inlet tract of the Carburetor. The other one takes the Carburetor
float bowl fuel expansion fumes and does the same thing. They both work to
reduce UHC in the atmosphere. I f they are serviceable, I would leave them
in place and make sure they work. Your experiences may vary.
Jim Hupy
Salem, Oregon

> Good evening all,
>
> I have a 1977 23' Birchaven with 2 Charcoal Canisters. Is it worthwhile to
> keep 2 canisters or only necessary to have one?
>
> Take care,
> Tom K.
> --
> Tom & Oki Katzenberger,
> Kingsville, Maryland,
> 1977 23' Birchaven, 455 C.I.D.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
 
The carbon canisters are engineering simplicity at it’s finest. Burning fuel vapors instead of venting to our atmosphere. I see no down sides to
having them, only benefit.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
> One of those canisters traps gasoline tank expansion fumes, and routes it
> to the inlet tract of the Carburetor. The other one takes the Carburetor
> float bowl fuel expansion fumes and does the same thing. They both work to
> reduce UHC in the atmosphere. I f they are serviceable, I would leave them
> in place and make sure they work. Your experiences may vary.
> Jim Hupy
> Salem, Oregon

As a side note: Our ‘74 has two emissions canisters connected in series as the tank vent. This was part of the California emissions which also
included gas tank heat shields on the exhaust pipe. (Coach was sold in Missouri so no idea why it has a CA emissions package.)
--
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
 
That's a strange one. 2 canisters were introduced with the 403 in
California equipped coaches in mid year 1977. 1978 saw all coaches
(California and 48 states equipped) with 2 canisters. But they are 40+
years old, and "little Tommy tinkerer" has had his way with them. All kinds
of changes have magically appeared in these coaches.
Jim Hupy
Salem, Oregon

On Tue, Jul 27, 2021, 6:32 PM Steve Southworth
wrote:

> > One of those canisters traps gasoline tank expansion fumes, and routes it
> > to the inlet tract of the Carburetor. The other one takes the Carburetor
> > float bowl fuel expansion fumes and does the same thing. They both work
> to
> > reduce UHC in the atmosphere. I f they are serviceable, I would leave
> them
> > in place and make sure they work. Your experiences may vary.
> > Jim Hupy
> > Salem, Oregon
>
> As a side note: Our ‘74 has two emissions canisters connected in series
> as the tank vent. This was part of the California emissions which also
> included gas tank heat shields on the exhaust pipe. (Coach was sold in
> Missouri so no idea why it has a CA emissions package.)
> --
> Steve Southworth
> 1974 Glacier TZE064V100150 (for workin on)
> 1975 Transmode TZE365V100394 (parts & spares)
> Palmyra WI
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
 
No Mystery Here.

At the time of production, there was an EPA rule that required the vehicle to absorb HC vapors based on the fuel tank volume. Many coaches were fit
with the series canisters. Mine was and is was sold in Michigan and later move to southern California.

To really answer your mystery, if you leave then alone you will never know that they are there. If like me, you want to decrease the spinach factor,
look at them carefully, and you can figure out how they are stacked and take out the one that is the add-on. As long as the vapor separator in the
left hind wheel well works, you will never know about it.

Matt
--
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
 
Thank you all. Mine are in a series. I think I will leave them as they are. I see no harm with the exception of more to go wrong. The best part is no
part I guess.

Take care and have a wonderful day,
Tom K
--
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D.
 
My 76 California coach came with and still has two canisters in series and also the exhaust heat shields.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Thank you Ken, I have exhaust shield as well. I thought someone just added them, perhaps they are factory.
--
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D.
 
The part is listed in the parts book as California only. Mine rusted the bracket and partially fell off. I rebuuilt it and reinstalled it again.
Jim K and another GMCer decided to start making them since it is a simple bent up piece of sheet metal (and mounting brackets) and easy to install. I
thought it was a good idea to try to keep exhaust pipe heat down and from entering the gasoline in the tanks.

JimK. Still has them and it is an easy improvement. I mention all of this because there are some unknoow number of these shields out there installed
by GMCers on non-California sold coaches.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
I forgot to connect this posting to the original title line. Dual canisters were a California thing too. Based on you finding both of these features
on this coach, it probably was first sold, or destined to be sold, in California. Nothing said that a coach built for California could not be sold
elsewhere in the US. I see no detriment to keeping both of these options.

> The part is listed in the parts book as California only. Mine rusted the bracket and partially fell off. I rebuuilt it and reinstalled it again.
> Jim K and another GMCer decided to start making them since it is a simple bent up piece of sheet metal (and mounting brackets) and easy to install.
> I thought it was a good idea to try to keep exhaust pipe heat down and from entering the gasoline in the tanks.
>
> JimK. Still has them and it is an easy improvement. I mention all of this because there are some unknoow number of these shields out there
> installed by GMCers on non-California sold coaches.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
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