1974 914 1.8, the mystery of the EC-A and EC-B Options

[wonkipop]

i'll be dropping the information we have gathered over Dec 2021 in with a set of posts.

the material was prompted by mr b ( @JeffBowlsby ) who observed that for the 74 MY there was an EC-A and an EC-B engine. mr b's thought was that the EC-A was a 49 states car and and EC-B was a californian car for emissions.

mr b's view was rational and reasoned. 73 EA engines are 49 states. 73 EB engines are california. 75 engines are documented in factory literature as EC-a (49 states) and EC-b (california). the logic should follow?

BUT

as per the mystery of the 914, the truth about 74 1.8s turns out stranger than fiction (or common sense?).

the material is not necessary to running a 1.8 or having fun with a 14. (IMG:style_emoticons/default/smile.gif)

its for historical purposes and as information to 74 1.8 owners to assist with restoration if they want it.

[wonkipop]

VAPOR EMISSION CONTROL SYSTEM

update information.

the emission warranty booklets included with cars when sold new provide the data that settles questions around the update change to the arrangement of the hoses to the charcoal canister that occur in 74 model year.

1.
1973 emissions warranty.
schematic diagram shown in booklet conforms to porsche design for hose hook up from 1970 model year on and agrees with diagrams in the factory workshop manual.
canister location front trunk.
canister type = metal, then plastic.
(source for diagram page - jeff bowlsby).





2.
1974 emissions warranty.
schematic diagram conforms to porsche design for hose hook up.
canister location = front trunk.
canister type = plastic.
emissions warranty dated VIII/73 = August 1973 (commencement of 74 MY production).
of note - emissions warranty is unique in applying only to 2.0L on cover.
this confirms that for 74 MY only 2.0 L cars were produced for the USA market from Aug to late Oct 1973 - 1.8 L cars commence production from late Oct/early Nov 1973.






3.
1974 emission warranty.
schematic diagram conforms to porsche design for hose hook up.
canister location = front trunk.
canister type - plastic.
emissions warranty dated X/1973 = October 1973.
this emissions warranty applies to the first batch of 1.8 L cars that are produced from late Oct 1973 until Nov 20 1973. For a period of approx 3 weeks 1.8 L cars are produced with front trunk mounted cans.
note - cover now includes both models, 2.0L and 1.8L as per all previous MY 914 emissions warranties.






4.
1974 emissions warranty.
schematic diagram is altered and hose hook up to canister conforms to VW design for all VW USA models since 1970. fan bleed hose and air cleaner intake hose alter positions on the can.
canister location = rear wall of engine bay.
canister type = plastic.
emissions warranty dated XI 1973 = November 1973.
this emissions warranty applies to the 1.8 L cars produced after Nov 20 1973 with the canister position revised to the engine bay location.
(the emissions warranty came with a car produced late Jan 1974).






5.
1974 emissions warranty.
as per #4.
(the emissions warranty came with a 1.8L model produced in April 1974).
the XI/73 emissions warranty is used through to the end of 74 MY production covering 1.8L and 2.0L models.






6.
1975 emissions warranty.
no examples of 1975 emissions warranties were submitted by members.
data will be posted if available in future.
canister location = engine bay position 2 (battery tray mount).
canister type = plastic.
EDIT SEPT 2023 - 2 examples of 75 emissions warranty submitted.
(both from 1.8) warranty dated VII/74 (July 74 - commencement of 75 production).











schematic shows a hook up consistent with with 1974 cars post Nov 1973 using VW design.
canister position = engine bay position 2 (battery tray mount).
canister type = plastic.


7.
1976 emissions warranty.
the separate emissions warranty booklet appears to have been deleted in 1976 and the warranty incorporated into the main glovebox owners operating manual.
note - only 2.0L cars produced for 76 MY.
schematic diagram shows a hose hook up consistent with 1974 cars post Nov 20 1973 using VW design.
canister location = engine bay position 2 (battery tray mount).
canister type = plastic.





--------

Front Trunk Mount.
Plastic Cannister.

applies:
early 74 2.0L cars produced from August 73 to late Oct 73.
74 1.8L cars produced from late Oct 73 - 20 Nov 1973.
fan feed hose connected to end of canister with vapor line.
air cleaner intake feed hose connected to opposite end of canister.





Engine Bay Mount (rear firewall)
Plastic Canister.

applies:
all 1974 MY 1.8L cars produced post Nov 20 1973 to end of model year.
possibly all 2.0L cars produced post Jan 1974 when 2.0L production resumes -
this data has not been confirmed and was not part of 1.8 L-Jet research - however the emissions warranty would appear to indicate 2.0 L cars are consistent with 1.8 L cars after the change to engine bay canister location.
air cleaner intake hose connected to end of canister with vapor line.
fan feed hose connected to opposite end of canister.
of note - criss cross layout of fan feed and aircleaner intake hoses in 1.8 L cars.

EDIT - JUNE 29 2022

refer page 2 of this thread. locating date of canister location changeover.
an example has been located with a probable production date commencement of Friday Nov 16 1973. the changeover seems centred around the weekend 17/18 Nov 1973.
the cars are not necessarily chronologically arranged in terms of Vin numbers during this changeover. so some frunk can cars may have been completed after engine bay can cars. the date however would be appear to be located at the very end of week 46 and the commencement of week 47 production in 1973.







EDIT SEPT 2023.
original condition 1975 1.8 (49 states car) showing mounting of canister in battery location with correct hose connections - matching schematic in emissions warranty booklet.






this information is not intended to offer technical explanation for the operation of the vapor emissions systems.
the information is data that has been confirmed and shows the system was changed.
there have been many discussions on this forum as to how this system works.
what has not been commented on in previous discussion is that Porsche were designing the system in 1970 with provision for a major vapor load after shutdown from a twin 3 barrel carburettor engine in the 914/6 and 911. VW were designing a system for either a much smaller vapor load from a single carburettor (beetles), or in some cases a twin single barrel carb set up on some buses, but by and large an EFI system with vapor load only from the fuel tank.
After 1973 Porsche cease to sell carburettor variants of their engine in the USA.
This likely explains the update to using the VW arrangement after that time.

updated vac hose layout diagrams for 1974 L jet cars to follow at a later date.
covering EC-A/EC-B throttle body to distributor vac hose hookup variations and
vapor emission hose hook up variations.