Rebuilding ECS

[akiran]

I think I'll rebuild the ECS for my (now my daughters) 1971 Monaco. With reference to Allpar's article Fixing 1970s Evaporation Control Systems I can do it with new parts. But I wonder if this is the suitable tank cap: GATES 31722.

I suppose the correct way is to connect the purge valve vacuun line to the distributors vacuum advance hose and the vapor line to the intake manifold.

 

[Davea Lux]

I think I'll rebuild the ECS for my (now my daughters) 1971 Monaco. With reference to Allpar's article Fixing 1970s Evaporation Control Systems I can do it with new parts. But I wonder if this is the suitable tank cap: GATES 31722.

I suppose the correct way is to connect the purge valve vacuun line to the distributors vacuum advance hose and the vapor line to the intake manifold.

The '71 ESC was a fairly simple design. These vehicles used a non-vented fuel cap. There were vent nipples on all 4 corners of the fuel tank and these were routed to a metal capture cylinder mounted inside of the vehicle trunk inside the right rear quarter panel. A vapor purge line was routed from the top of the metal cylinder to the right side of the engine compartment where it was hooked to the right side engine breather. The engine crank case was used as a vapor collection repository. A second hose nipple on this breather cap was hooked to the carb bowl vent to provide a vent for the fuel tank to keep it from operating at a vacuum as fuel was drawn out by the fuel pump. The vapors that collected in the engine crankcase would then be drawn off thru the PCV valve when the engine was started. This system did not work very well in practice and frequently resulted in hard starts when the vehicle was warmed up due to an over rich mixture as the fuel vapors were drawn into the PCV system. '71 Mopars with Federal emissions did not use a charcoal pot or a purge valve.

A lot of these systems had the vapor line unhooked from the engine breather and blocked off. A vented gas cap was then installed to cure the hard start issues from fuel vapors collecting in the crankcase. This of course defeated the purpose of the ESC but made the vehicles more pleasant to drive.

Dave

 

[CBODY67]

What would it take to upgrade the '71 system to what was on the '72 Federal-spec emissions cars, which had the carbon cannister (with the purge valve on top of the cannister)?

CBODY67

 

[Davea Lux]

What would it take to upgrade the '71 system to what was on the '72 Federal-spec emissions cars, which had the carbon cannister (with the purge valve on top of the cannister)?

CBODY67

The carbon canister would need to be installed at the end of the line that comes from the capture cylinder in the trunk instead of being installed on the breather cap on the valve cover. The purge valve is then teed into the vacuum line for the distributor vacuum advance so that it is only open when the engine is running above an idle. The purge line from the canister is then teed into the PCV valve line. The '72 and later systems did not use the capture cylinder in the trunk as a redesigned gas tank with a domed top was used to capture vapor. This got rid of the need for the four corner nipples which were replaced a with a single hose from the top of the dome. The '71 system will work without changing to the domed tank if the above modifications are used.

Dave

 

[akiran]

For European Economic Community (EEC) directive No. 70/221 my '71 car is equipped with system to reduce air pollution. It seems that in Europe we got this better system about year earlier. There are four lines from tank to separate collector for fumes, line from collector to the front and a coalcanister in corner of the engine bay. So it's very simple to rebuild with new components and stop the gas smell in garage.

 

[Davea Lux]

For European Economic Community (EEC) directive No. 70/221 my '71 car is equipped with system to reduce air pollution. It seems that in Europe we got this better system about year earlier. There are four lines from tank to separate collector for fumes, line from collector to the front and a coalcanister in corner of the engine bay. So it's very simple to rebuild with new components and stop the gas smell in garage.

You might check your build sheet as that sounds a lot like the California package for '71. The charcoal canister rarely fails, most likely you have a bad hose someplace. If you are smelling fuel, check your fuel pump and lines for leakage, also the carb might be dripping from a bad float or needle valve.

Dave

 

[70bigblockdodge]

Not going to fix fuel smell. When the car is shut off. Bowl vents in carburetor are venting to air cleaner which without air flowing in fumes will flow out.

 

[CBODY67]

Not sure what the EEC directive means, but by that model year, ALL Chrysler products were designed to reduce air pollution. Just that the evap emissions was added after '70s, in one form or another. What does the tune-up decal under the hood state, as to what the base timing might be and such? The timing spec might be a way to tell if it's really got the CA spec or the normal Federal spec, of whatever.

Just some thoughts,
CBODY67