Emissions Control System ID help, 1971 Duster 340

PlymCrazy

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Pretty certain "yes" that is no vent on non-ECS
Now I’m confused. A non-vented cap I’d think goes on an ECS car. The way I’m understanding ECS at this point is that it DOES NOT allow for gas vapor to vent to atmosphere but rather sends the unused vapor back into the fuel system to be burned. Please set me straight here.
- Nick
 

autoxcuda

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This is a N95 Automatic non A/C car owned by GY3 71 Demon talked about in this thread here: 1971 340 Restoration reference photos

Not sure what applies here to an N95 4-speed car. Notice the speed sensor that is tapped into the speedo cable in picture #3 under the master cylinder.

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autoxcuda

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Wow, you lucked out.

Steve Cabral's 71 340 4spd Duster is an N95 car.

Follow everything you see here. One of (if not THE) the most correct restored 71's around.. and it's a N95 car.

Steve's great guy, and goes by steve70 on Moparts.

It looks like it has the passenger cowl mounted electronic device. That connects to a bracket on the back of the motor that I think has a themostat or something (can't remember). I doesnt' look like there is a Speed Sensor. But I would ask Steve to make sure.

Steve Cabral’s 1971 Plymouth Duster 340 has been restored to be the finest example of an A-Body

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67Dart273

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Now I’m confused. A non-vented cap I’d think goes on an ECS car. The way I’m understanding ECS at this point is that it DOES NOT allow for gas vapor to vent to atmosphere but rather sends the unused vapor back into the fuel system to be burned. Please set me straight here.
- Nick
I got caught up in improper terms. NONE of the pre-70 or the 70 without evap was vented. It is an obvious, solid cap when you look at it, and the vent is a tube welded into the high end of the filler neck inside the trunk, and then leads down and exits through the trunk floor grommet

None of the evap controlled cars are "truly" vented. That is the caps are not intended to operate as a vent. They were / are known as "pressure vacuum" caps because they have spring loaded pressure relief valves to let in or let out pressure after some build-up. The operational vent in those cars is provided by the tube running up to the engine bay.

If you have not done so I really again suggest you download the 69---about 73 manuals there from MyMopar and read the fuel and emissions sections.
 

67Dart273

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Frankly if I had an Evap controlled car---and did not care about "restore correct" and did not have to argue with a state emission program, I would modify the filler neck to act as the 69/ earlier vent system. The one problem with this is, that due to the vent tube, the 69/ earlier tubes must be installed from the trunk before the tank is connected, and the EVAP models can be shoved in from the outside. You could brase a flush or nearly flush fitting into the tube that would slip through the fender hole.

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PlymCrazy

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Wow, you lucked out.

Steve Cabral's 71 340 4spd Duster is an N95 car.

Follow everything you see here. One of (if not THE) the most correct restored 71's around.. and it's a N95 car.

Steve's great guy, and goes by steve70 on Moparts.

It looks like it has the passenger cowl mounted electronic device. That connects to a bracket on the back of the motor that I think has a themostat or something (can't remember). I doesnt' look like there is a Speed Sensor. But I would ask Steve to make sure.

Steve Cabral’s 1971 Plymouth Duster 340 has been restored to be the finest example of an A-Body

View attachment 1715992395
Always wondered what that device was for. Asked some Mopar guys in my circle in the past and no one could give me a solid answer. Appreciate you bringing that to my attention.
- Nick
 

PlymCrazy

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Frankly if I had an Evap controlled car---and did not care about "restore correct" and did not have to argue with a state emission program, I would modify the filler neck to act as the 69/ earlier vent system. The one problem with this is, that due to the vent tube, the 69/ earlier tubes must be installed from the trunk before the tank is connected, and the EVAP models can be shoved in from the outside. You could brase a flush or nearly flush fitting into the tube that would slip through the fender hole.

View attachment 1715992400
I will consider this if I can’t get the right cap for the current setup. Appreciate all your input here sir. Priceless as is many folks advice around here.
- Nick
 
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