ECS (N95) Delete - Mods for single vent tank

[dylo]

Hi all,

My '70 has the N95 options and its come time to replace my rusty gas tank. Issue is the only tank I could get here in Australia has the just the gas outlet and the single vent on the passenger side of the tank.

My question is; Would it be as simple as removing all the 4 vents and vapor separator junk and just running my tanks single vent to the existing vapor line that travels all the way to the canister on the rocker cover? This has the three prongs for the N95 ECS system which goes to the air filter and carb. Or would doing this cause gas to be sucked into the vapor line if the tank were full?

I don't have the little standard gas vapor 'U' shaped piece to otherwise vent into the frame rail, hence why I was trying to use existing parts.

Thanks again,

[dylo]

I have come up with a solution which id love some feedback on if anyone knows these 70/71 ECS systems inside out.

My idea will now include the existing vapor separator (tower style) in the trunk wheel well area and i will not delete anything apart from 3 of 4 tank corner vents. I will block off three of the tank (corner) vents at the vapor separator and plumb in my single tank vent into the remaining inlet at the separator (the shortest tube). This means it will also drain back out of it if gas were to get up there, returning it to the tank. Using this method the original vent to the carb air-filter out of the separator can remain (via the tallest tube in the separator).

Confusing?!

[Skdmark]

What if you were to modify the tank to have the lines added?
Not sure if this illustration from the FSM helps.

[dylo]

I have got the ECS working with the one vent tank. Just incase anyone wants to do this in the future there are a few bits of information that are required that are not covered anywhere I could find in the Service Manual.

The shortest tube which would be the best to drain back out of the ECS tower to the tank in a one vent instance is actually the second one in from the rear of the car. The pictures in the FSM look to show the rear-most tube being the shortest.

There is a sneaky check (one way) valve that lives inside the vapor return line just under the passenger footwell area before it heads up the firewall. Mine was seized and causing a complete blockage but I was able to free it with some brake cleaner and compressed air until it worked freely. It can be seen if you look up the line with a torch.

[Cuda Cody]

Has anyone put a mirror in a reproduction gas tank and cheeked to see if they have an expansion tank?  I don't think they have that!

[dylo]

Has anyone put a mirror in a reproduction gas tank and cheeked to see if they have an expansion tank?  I don't think they have that!

Im not sure but I would also highly doubt it. If they did, there should be a small rubber bung in the center of the top of the tank that allows access into the expansion tank.

[Cuda Cody]

Some old guy who knew a lot about these old mopars once told me it was just a tank inside the tank that didn't fill up fast.  So when you filled the car with gas it would seem full even though it had a small space left and when the temperature changed slooooly over time the gas could expand in to the tank.  And as the gas is used up it slowly drains back out.

[dylo]

Yes that's my understanding of the system too Cody.

As the gas fills that small tank the main tank level will drop and eventually expose at least one of the four vent tubes that would otherwise be submerged in a 100% full tank. Then any vapor is able to go through the vapor separator tower in the trunk and either re-condense and return to the tank, or be burnt via the vapor return line to the air filter.

Its quite ingenious really!

[floorit426]

Has anyone put a mirror in a reproduction gas tank and cheeked to see if they have an expansion tank?  I don't think they have that!

I just installed a Spectra tank, in my '70 Cuda, w/ECS. There was no internal tank, but each of the four tubes were placed, one to a corner. I think the plan was that at least one tube would be vented, regardless of how the car was parked.

[shawge]

Attached a view of the Tanks Inc efi tank. No expansion tank, there is a vapor line at the top of the tank and also one on the fuel pump flange. I added Y barbs to these lines and attached them to the 4 ports on the separator, and had the vapor line attach to the crankcase air cleaner as before.