Evaporative Canister - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**truckster** · 09-26-2020, 11:05 AM

If I understand the operation of the canister correctly, one port is connected to the evap line from the fuel tank, one is connected to ported vacuum on the carb, and the third goes to a T in the PCV hose.

Is this correct? If so, does anyone know where I can buy a canister that will fit?

**Getter-Done** · 09-26-2020, 12:00 PM

They come up for sale here from time to time.
I don't if this one sold it's an old link.
Link: http://67-72chevytrucks.com/vboard/s...light=canister.
He a good guy to buy parts from.

.

Andy4639 · 09-26-2020, 01:13 PM

Here is the picture out of the service manual I blew it up.

**Steeveedee** · 09-26-2020, 01:49 PM

NAPA carries them. Looks like the second one on the page, IIRC.

https://www.napaonline.com/en/search...Qualified=true

**truckster** · 09-26-2020, 02:53 PM

Thanks for all the help. The links and the pictures are very helpful.

I have a question about the one in the NAPA link - I found a similar AC Delco and a Dorman unit as well. All three seem to have a cap partially covering one port that's labeled "Air" and is open to the atmosphere. Is that the one that would connect to the PCV?

**Steeveedee** · 09-26-2020, 05:37 PM

Quote:

Originally Posted by truckster

Thanks for all the help. The links and the pictures are very helpful.

I have a question about the one in the NAPA link - I found a similar AC Delco and a Dorman unit as well. All three seem to have a cap partially covering one port that's labeled "Air" and is open to the atmosphere. Is that the one that would connect to the PCV?

If it is a 3/8" nipple, probably. It's a 5/16" (could be 1/4") to the tank vent line and then a 3/16" to a vacuum source. I'm dredging up 30+ year old memories on this stuff. I graduated uni in '84 and went to work as an engineer...and now I'm retired. My '70 truck is no help, as 3/4T didn't get that equipment until later.

**dmjlambert** · 09-26-2020, 08:52 PM

I've been looking at these and reading about them. I am not an expert, so take what I say for what it's worth. I believe the ones that do not have an obvious purge valve on top with a separate small vacuum connector, and with only 2 connections without dust cap do not have a purge valve integrated into them. You would have to buy a purge valve to put between the PCV hose T connector and the canister. So, I think the the ports are fuel tank, and purge, and the air port is there to let fresh air in. The one in the forum for-sale listing looks like the entire top is broken off the purge valve. If I were setting this up for my truck, I would get a new canister with the 2 connections (plus air inlet) and get a separate vacuum operated purge valve.

**truckster** · 09-26-2020, 09:18 PM

The pic Andy provided doesn't show a purge valve as far as I can see. It looks like it just hooks into the PCV system with a T.

**dmjlambert** · 09-26-2020, 09:30 PM

Yes, that is because the valve was integrated on top of the canister. Those are terrible pictures, no good detail. Just for hose routing, and not really good for that.

Andy4639 · 09-26-2020, 10:07 PM

Here are some more but not for the purge tank. Not at the house so I can't look through my manuals to see if there is anything better.

**truckster** · 09-26-2020, 10:32 PM

OK, makes sense. I've got a purge valve on the way.

Those things sure are expensive...

**rechinca** · 09-26-2020, 11:37 PM

I may have a canister/bracket in my parts stash. I won’t be able to check until Sunday afternoon, but PM me if you are interested. If memory serves, it will need a new filter at the bottom and the charcoal for it (filter is available and charcoal can be sourced on Amazon). Not sure which one/year it is, but the canister and valve up top were intact.

**71CHEVYSHORTBED402** · 09-27-2020, 01:09 PM

A good canister is hard to find, but they can be had. Here's some info. for a 1971:

Original canisters for 1971: 7028129 or 7030541: The canister on my truck was 7030541.

GM replacement canister: 7030605

Another replacement that works: 17063011. The "Carb Bowl" is sealed on at least some of these canisters. The Carb Bowl is not used for a 1971 Chevy truck.

**truckster** · 09-27-2020, 02:13 PM

I was able to find the GM 7030605 online for $75. Rechinca, I may have my old bracket, but I have to sort through my parts stash to make sure. Thanks for the offer - I'll PM you if I need it.

Thanks for all the help.

**rechinca** · 09-28-2020, 09:46 AM

Quote:

Originally Posted by truckster

I was able to find the GM 7030605 online for $75. Rechinca, I may have my old bracket, but I have to sort through my parts stash to make sure. Thanks for the offer - I'll PM you if I need it.

Thanks for all the help.

No problem. I know I have a spare bracket too if you can't find it. Sorry I didn't get back to you. Went to the Turlock swap meet and got back late.

09-26-2020, 11:05 AM	#1
truckster Senior Member Join Date: Jan 2001 Location: Orem, Utah Posts: 7,789	Evaporative Canister If I understand the operation of the canister correctly, one port is connected to the evap line from the fuel tank, one is connected to ported vacuum on the carb, and the third goes to a T in the PCV hose. Is this correct? If so, does anyone know where I can buy a canister that will fit? __________________ I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson

09-26-2020, 12:00 PM	#2
Getter-Done Senior Member Join Date: Dec 2009 Location: TN. Posts: 7,696	Re: Evaporative Canister They come up for sale here from time to time. I don't if this one sold it's an old link. Link: http://67-72chevytrucks.com/vboard/s...light=canister. He a good guy to buy parts from. . __________________ ________________________________________________________________________________________ ____________________________________________ 84 Chevy K-20 63 Impala (my high school car) http://67-72chevytrucks.com/vboard/s...Crew Cab Build

09-26-2020, 01:13 PM	#3
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: Evaporative Canister Here is the picture out of the service manual I blew it up. Attached Images __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

09-26-2020, 01:49 PM	#4
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,076	Re: Evaporative Canister NAPA carries them. Looks like the second one on the page, IIRC. https://www.napaonline.com/en/search...Qualified=true __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

09-26-2020, 02:53 PM	#5
truckster Senior Member Join Date: Jan 2001 Location: Orem, Utah Posts: 7,789	Re: Evaporative Canister Thanks for all the help. The links and the pictures are very helpful. I have a question about the one in the NAPA link - I found a similar AC Delco and a Dorman unit as well. All three seem to have a cap partially covering one port that's labeled "Air" and is open to the atmosphere. Is that the one that would connect to the PCV? __________________ I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson

09-26-2020, 08:52 PM	#7
dmjlambert Senior Member Join Date: Apr 2016 Location: Cypress, TX Posts: 3,554	Re: Evaporative Canister I've been looking at these and reading about them. I am not an expert, so take what I say for what it's worth. I believe the ones that do not have an obvious purge valve on top with a separate small vacuum connector, and with only 2 connections without dust cap do not have a purge valve integrated into them. You would have to buy a purge valve to put between the PCV hose T connector and the canister. So, I think the the ports are fuel tank, and purge, and the air port is there to let fresh air in. The one in the forum for-sale listing looks like the entire top is broken off the purge valve. If I were setting this up for my truck, I would get a new canister with the 2 connections (plus air inlet) and get a separate vacuum operated purge valve.

09-26-2020, 09:18 PM	#8
truckster Senior Member Join Date: Jan 2001 Location: Orem, Utah Posts: 7,789	Re: Evaporative Canister The pic Andy provided doesn't show a purge valve as far as I can see. It looks like it just hooks into the PCV system with a T. __________________ I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson

09-26-2020, 09:30 PM	#9
dmjlambert Senior Member Join Date: Apr 2016 Location: Cypress, TX Posts: 3,554	Re: Evaporative Canister Yes, that is because the valve was integrated on top of the canister. Those are terrible pictures, no good detail. Just for hose routing, and not really good for that.

09-26-2020, 10:07 PM	#10
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: Evaporative Canister Here are some more but not for the purge tank. Not at the house so I can't look through my manuals to see if there is anything better. Attached Images __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

09-26-2020, 10:32 PM	#11
truckster Senior Member Join Date: Jan 2001 Location: Orem, Utah Posts: 7,789	Re: Evaporative Canister OK, makes sense. I've got a purge valve on the way. Those things sure are expensive... __________________ I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson

09-26-2020, 11:37 PM	#12
rechinca Senior Member Join Date: Jul 2018 Location: Vacaville, CA Posts: 528	Re: Evaporative Canister I may have a canister/bracket in my parts stash. I won’t be able to check until Sunday afternoon, but PM me if you are interested. If memory serves, it will need a new filter at the bottom and the charcoal for it (filter is available and charcoal can be sourced on Amazon). Not sure which one/year it is, but the canister and valve up top were intact. __________________ 1971 Custom/10 - 350/3 speed, Orange/White roof

09-27-2020, 01:09 PM	#13
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,114	Re: Evaporative Canister A good canister is hard to find, but they can be had. Here's some info. for a 1971: Original canisters for 1971: 7028129 or 7030541: The canister on my truck was 7030541. GM replacement canister: 7030605 Another replacement that works: 17063011. The "Carb Bowl" is sealed on at least some of these canisters. The Carb Bowl is not used for a 1971 Chevy truck. __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring it from ground up. With assys, the guide accts for 1000s of OEM identifications and part numbers, all written in short order. 700+ images include assm, illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025

09-27-2020, 02:13 PM	#14
truckster Senior Member Join Date: Jan 2001 Location: Orem, Utah Posts: 7,789	Re: Evaporative Canister I was able to find the GM 7030605 online for $75. Rechinca, I may have my old bracket, but I have to sort through my parts stash to make sure. Thanks for the offer - I'll PM you if I need it. Thanks for all the help. __________________ I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson

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