ok guys.

@JeffBowlsby and i have come across a historical question on the history/originality section of site. its been discussed for a year or so now.

would be good to get to the bottom of it. not that it matters much to making your car run and it.

what we need is an image from the emissions warranty.

from each model type. 1.7s, 1.8s, 2.0s and sixers for each model year.


here is the anomaly.

from my car. 74 1.8

Click to view attachment
Click to view attachment

jeff has this up his excellent website of historical documentation.

from a 73

Click to view attachment

those of you with a sharp eye will notice they are different.
see where fan hose goes.

--------

the difference is of interest as it may be tied to how to correctly plumb the EVAP cannister after the change to engine bay location. or it may not?
most of us probably don't care too much, but for those that might it could be interesting.
another one of those 914 mysteries maybe.

if you still have an emissions warranty, take a pic and post them up if you have time.

Pelican Parts has full diagrams of all motors. A good place to look. People here might have those already just know of PP's.

thanks @bandjoey .
have most of that stuff already.
pp material on 911s has been thoroughly and accurately tracked on that forum.

looking for the same now with the 914.
1) tracking/verifying the two different systems known to be used on the 914.
2) finding where changeover happens and whether it is uniform changeover on all models or at different points in time for 1,.7/1.8 v six and 2.0.

emissions warranties that came with cars (+ diagrams) are good data.

Very interesting!

@wonkipop I hope you like worms because you just opened a can of them lol!

Needless to say, I'll be switching mine back to the PROPER configuration now! Hahaha!

They show both in the service manual. Seems to me that one uses the air from the fan housing to push the fumes from the evap. tank into the throttle body while the other might push the fuel fumes back into the evap. tank. Am I missing something?

Well this is the mystery wonkipop is after. His car and mine were produced weeks apart and we have a different layout but the exact same parts. No difference in the canister, it's location, or anything else. Only an unexplained reverse hose layout... His is reversed (wonky) BTW, mine is normal! Just wanted to make that clear as this thread develops

Something I had forgotten about this diagram is that it inaccurately depicts the fuel vapor supply pipe in the charcoal filter can as extending through deep into the charcoal media. If this were so, then fuel vapors would be deposited to the far end of the canister and the supply air from the fan would direct the fuel vapors though the media so that the canister functions as intended

In reality that fuel vapor pipe in the plastic late 74 and later is a stubby, so that filtering is negligible when hooked up the 1973 way. Photo depicts the canister when opened looking into the far end. So this 1974 manual diagram works if the plastic can was built with the longer pipe, but it was not.

I wonder how the inside of the 1973 and earlier metal can was constructed? Maybe they changed the piping due to intended can construction changes which may have affected the plumbing layout? Maybe the plastic cans were subject to cost reductions and they shortened the supply pipes?

Jeff, mine is the same and it’s a 12/73 build date.

From an engineer’s perspective (mine), the system work be more effective with a short stub in the given diagram. Presuming the function of the canister is to capture gas (petrol to some…. ) fumes during refueling:
1. Fumes get pushed up the gas tank through the chamber and into the canister, where the activated carbon “captures” the hydrocarbon fumes. A shorter stub allows the fumes to be exposed to more carbon. This, of course, assumes that the tank is being filled with the engine, hence fan, off.
2. When the engine (fan) is on, the positive pressure forces the hydrocarbons off of the carbon and into the air inlet, allowing the fumes to be combusted instead of being released into the atmosphere.
A longer tube would expose the hydrocarbons to the charcoal on the far side of the canister, forcing them to be sent back across the carbon where they could get redeposited hence not evacuated from the canister. The fan air probably adds some back pressure to the chamber and the gas tank but not much; that pressure forces the fan air and fumes out the other outlet into the air intake.
With the longer tube, yes the system would need to be plumbed differently so as to avoid that redistribution/redepositing situation.
These are how industrial hydrocarbon emission reduction filters work, though often the carbon is removed and regenerated by exactly the same process as we have but in bigger, higher tech and probably more efficiently.
Whew!

yep, its something like that jeff.

and @Van B emission booklet is part of the mystery.
and right in line with what i would have thought.

something is going on right about the time the 1.8s come on line from nov 73 on.
just like using up frunk cans first, they don't hand out the new booklets until the old ones are used up? none of it happens on exactly one car all together at one time.

thanks for posting up the stuff guys.

lets see what other members might have to throw more light on things in terms of their emission warranty booklet. particularly interested in see the 75 and 73 booklets.



a thing to bear in mind at this point in time is whether it is assured that the booklets people have are original to the cars. after half a century some previous owners may have completed missing items with booklets purchased to replace lost ones.

i do know mine is the one that came with the car.

without going into a debate about how they work which is not really the purpose of this thread, its really just to gather data at this point. - i would say this. you need to consider the behaviour of the can in the static phase. ie sitting there with the engine off. which is the other phase the can operates in, not just the dynamic state.
secondly, the release of the fumes from the charcoal is akin to a chemical reaction.
the carbon in the hydrocarbon is attracted to the carbon in the charcoal, thats how they get the fumes to stick to the activated charcoal. releasing the fumes is not so much blowing on them as flooding them with oxygen. the oxygen makes the charcoal release the hydrocarbons. thats really how the can works. on top of that the can is also the fuel tank ventilation "valve". it is what lets the air in to the tank to stop it being collapsed by a vacuum as you use up fuel. its a complex little device and its a passive device when compared to the systems used by most other manufacturers.

but enough of that for now. its the emissions booklets we need to get hold of first.
more material for jeff bowlsby's fab collection of documents on his website.

@Van B . @JeffBowlsby
re the different cans leading to different layouts.
metal v plastic.
i would say no.

thats on the basis of what VW do with all their cars.
VW plumb the cans as per my emission warranty in all their models from 1969 on.
never change the plumbing. the can is updated along the way to plastic as per the 914.
but nothing in the plumbing of which hose to which end of can changes for VWs.


I think if we can get some more emissions warranties we might get some useful data.
particularly whats either side of 1974 in the 73 and 75 model year cars.

@Van B

ok, you have not opened up a can of worms with your emissions warranty.
you have shone a light on things. i just had a good look back through our EC engine research stuff.

i think i can see something which puzzled me before doing EC engine research.

take a look at this.
(to slightly correct you, my car is not built within days of your car. mine is a good month and a half after yours and in 74 not 73).
but this car (image following) we found in our research of EC engines is built within days of yours. it was built on the friday 7 dec 73 and yours on the monday 10 dec 73.

i'd looked at it before and noted at first glance it had the same s curve hose from fan to lhs of can as my car but also noticed the can was around the other way from my car. pointy end of can oriented to lhs with fuel vapor line coming in that side. i thought someone might have reinstalled the can the wrong way around and messed it up. however its an extremely original car in all respects and in very good condition.
and the can in this orientation with this configuration of plumbing would match your emissions warranty from nearly the same date of manufacture.

Click to view attachment

i would have loved to have been able to look inside the emissions warranty for this car.
its exactly like yours with the same diagram?

Click to view attachment

my question to you, which i have not thought to ask before - is which way is the can oriented in your car Van. is it with the pointy end to lhs and vapor line coming around to that end of it. along with fan line. and aircleaner line coming in to the rhs side which only has the one connection.

you can possibly see where i am going with this?

need a few more cars. just to work out if this yellow car is for real. i think it might be though.

I have the same question for steve @StarBear as above. which way was can originally oriented in your car. yours is a 73 manufacture date like Vans. i know you lost the original emissions warranty steve and you have replaced it. but in the replacement one you have which diagram do you have in it anyway. is it the one like mine. or the one like vans. just to accumulate more material. and to rebuke that very naughty comment from jeff that mine was a misprint.

------

now look at this one.

my car is end of jan 74 car.
it has the S shaped hose from fan to flat end of can with single port.
the single port is on the lhs.
on the rhs of can which is pointy side, it has the aircleaner hose and the vapor line.
and all of that matches the diagram in the emissions warranty and is original in terms of the engine bay. i have never changed it. the car is still original and was competely original when i bought it in 89.

now here is another example.
this was also part of EC research material we had.
this is the car the dr914 owned for a while in the AA collection.
very low mileage, very original 1.8.
the car is a feb 74 build.
it exactly matches mine.
the can is oriented the same way mine is.

Click to view attachment

i would have loved to have seen the emissions warranty for the AA car.
it matches the one that came with my car?

----------

i think we have been missing something else that was going on with the 1.8s.

yes they shift the can from frunk to the engine bay.

but it kind of blinded us maybe to a second change that happened which did not coincide with that. i had certainly been assuming that any change in the plumbing of the can co-incided with the change over to the engine bay can.

i don't think it did now. i think it happens after that. its pretty subtle, but i no longer think that yellow car with the can oriented the other way around is wrong. its correct for when it was manufactured and it accords with the design in place at the time?

its after that the design is amended and the plumbing is reversed.

the same thing happens with 911s by the way. during the 1974 model year the plumbing in the can was reversed. i did some reading up on this on the P P forum and came across the thread on the 911 evap emissions system. a very extensive thread covering it all in detail and including the diagrams. a posting on that thread noted the changeover in 911s occured mid model year 1974. that would be right around december73/jan 74.

i think we might be inching closer to cracking this mystery.

there are 2 changes to the evap system in 74MY?
1) can location changed to engine bay. known to be very likely Nov 20 1973.
2) can plumbing revised? probably start of jan 74? maybe?


having some more emissions warranties from 74 models (both 2.0 and 1.8) either side of dec 73 / jan 74 will start to shine more light on this.

i doubt it makes any difference to the function of the can.
and thats not the issue here with this thread - not which can works better in our opinion etc. i don't think anyone is right or anyone is wrong.
what i am interested in is that porsche changed it. we know that.
they changed it on the 911 and they changed it on the 914.
all i want to know is the date they changed it.
and the details of the change.
which we just added potentially to with a detail previously overlooked.
namely there were two versions of the rear firewall of the engine bay variant?
if that is so, no one has picked up that little detail before.
and it will only be on 1.8s too. not 2.0s.
it will be in that period of 1.8s after the change from the frunk can up until sometime between 10 Dec 73 and 25 Jan 74. because they are only building 1.8s during that period.

------

i do have a view on the frunk cans in terms of how they work.
and this is not to add to the back and forth about pushing or pulling air, or does the fan blow air, or does engine induction suck air etc and etc.

and that is the frunk can had an inbuilt fault.
look closely at the vapor line.
it runs down hill from the expansion tank to the can.
vapor condensing in the line can run down into the can as liquid fuel.
thats one way to kill the charcoal in the can pretty quick.
911s with front mounted cans pre 74 do not have this fault.
they have an extra expansion vent tank that prevents condensed vapor running down into the cannister. this extra expansion vent tank is not in the original 914 front mounted can scheme.
i think fixing that fault is the reason for shifting the can to the engine bay.
the vapor line descends to go through the tunnel and ascends to get to the can.
any condensed vapor in the line runs downhill away from the can.

this is separate from the matter of then going on to rearrange the plumbing to the can after that.


more data is needed.

though in the end its only of interest to a restorer seeking authenticity.
and thats all this research is intended for.
just to lodge the material to assist restoration and to have it filed in the originality section of the website for future owners.

@wonkipop
Mine is oriented as two hoses on the right, with the small evap hose on bottom.
Further, when I took it apart, it was clear from the marks on the plastic case that it had been in only that orientation for it's whole life despite the fact that someone had refilled it (with the wrong pellets) at least once before.

I think your originality pursuit is a good one even for guys like me who would never do concourse. For most of us, I think we'd all agree it's cool that 50yrs after this car was produced, we are still accumulating knowledge as a community that quite possibly wasn't fully known by anyone outside of the factory! Ref your email to the Porsche museum lol!

Hopefully, some 2.0 guys will start chiming in soon *wink wink, nod, nod*

I checked and confirmed that mine is oriented and plumbed as shown on page 5 of the warranty booklet. Small fume inlet on small end, passenger/battery side.
@wonkipop ; you are correct- I don’t recall ever getting/ keeping my original booklet but got an “ok” original a while ago.
@van b ; finally remembered to look at that “error” in the sales brochure. You are spot on with that photo of the guy loading the luggage. A few other pics show no bumper eyes in a few other photos and no front side marker lights in two photos of the yellow car.

what i was asking @StarBear was is the emissions warranty you picked up a version like Van B or is it like mine. see the fan hose hook up difference. just want to see which one it is.

its going to need a few members with emissions warranties that came with cars to be able to place the two different diagrams in emissions warranty with the set up.


Click to view attachment
Click to view attachment

i don't do concourse either. reason being exactly this kind of stuff. as we can see from what we have been doing with EC-A or EC-B etc, there are no experts when it comes to this. its never been researched.

jeff bowlsby got me fired up on this with his revelation about the EC A and B versions.
boy - thats one for the history books. they all said the EC engine was a 50 state car.

i also admire how VW did one of the best jobs during the malaise era.
with such small engines in their cars they could not afford to lose power output.
they did a remarkable job when you compare them to just how much the USA domestic manufacturers suffered in terms of performance loss.

slight diversion.
@StarBear and @Van B
by bumper eyes i'm guessing you guys are talking about covers for holes in the bumpers where tits mounted on USA models.
here are my photos of dr. marchant car in porsche museum from 10 years back.
euro spec 74s did not have drilled holes or covers.

Click to view attachment
Click to view attachment

SB is talking about the 1970’s photoshop work they did to the sales brochure for 1974 that used all the same photos but they painted in the different color turn signals and drew the bumpers onto the old stock photos. They did pretty good work, but once you see it, it cannot be unseen lol!

It’s like yours. How does my VIN and date compared with yours vs Van’s?
As noted, this isn’t the pamphlet that came with my car, as I don’t recall getting or keeping one. The setup matches, though.

Yep, and that museum car doesn’t have side marker light, either. Still learning and seeing new things!

righteo. thanks for that mate.

so far then two of the wonki sort , one of the normal.
see if some more owners pop up and with what variety.

you mean this.

Click to view attachment

--------

Click to view attachment


ever noticed this one.
from 69.
someone did a half decent job with the airbrush on the gas burners.
mahle hadn't managed to make the wheel yet?
(notice the prop holding the trunk lid up, its a pre production car or prototype )

Click to view attachment


back to emissions warranties.

@Van B + @StarBear .

another detail to have a look at on your emissions warranties when you have time.

looks like mine maybe has a date on it?
hard to figure out.
XI/73 might mean Nov 73? when it was printed? 2 months prior to the car being made.
wondering if there is earlier or later numbers there that date the emissions warranties throughout the model year.


Click to view attachment

the glovebox manual has a similar XI/73 on it.

Click to view attachment

@Van B + @StarBear + @JeffBowlsby

i might be on to something with the date of emissions warranty.
did a quick google image search.
popped up an ebay ad.

this one is described as VIII 73. roman numerals for 8.
if it is a date = august 73,
pity more pages of inside of warranty booklet were not in ad.
included diagram remains elusive.

i think these things might have been printed in monthly/quarterly/half yearly batches?



Click to view attachment
Click to view attachment


EDIT
there is something going on with dates with warranty booklets.
i dug up VW 74 emissions booklet i had on file.
doesn't use roman numerals. i assume this one means nov 73 too?

Click to view attachment
Click to view attachment

i found this on file when looking for the vw emission warranty.
for those of you interested -
its the VW technical explanation for the operation of the cannister.

which is a little different to views here on how it works.


when the engine is off and the can is not over oxygenated the charcoal absorbs the fuel vapors. the depth/amount of charcoal absorbs enough of the vapors that they do not escape through the blower port which is open to atmosphere. in effect the charcoal is sufficient to act as the valve. VW (and porsche) are entirely on their own with this. every other auto manufacturer at the time fitted a valve to the charcoal cannister.

when the engine runs the fan provides enough air quantity to flood the charcoal with oxygen to activate it - releasing hydrocarbon fumes. engine intake (vacuum in effect/air being pulled) draws those released vapors off and into engine. the fan provides just enough pressure (and it isn't much - i've pulled the hose off and stuck my finger there, its not a huge flow) that fumes do not back flow through fan into atmosphere. the whole system is slightly pressurized over atmosphere to ensure flow in one direction. into engine (and into fuel tank to replace volume of used fuel?). the space at the end of the can with the springs in it allows the fan flow of air to spread across the end of the can and filter through the entire cross section.

at least thats the way VW think it through.

porsche had the opposite idea from 69 to 73. it could be that they thought induction pull from the 6 carby barrels of a 911 6 cyl was such that it worked better the other way around in their minds. ie the strong suction force was taken at the end of the can with the spring formed space. i think they engineered the system with the 911 914/6 in mind? but maybe did not give enough thought to whether it worked with the cooling fan and induction flow of the 4. VW only dealt with their little 4 cylinder engines in their range of cars.

i've got a funny feeling that fuel tank vacuum in the 911 or even the 914/6 may have been playing into it. 911s consume a lot more fuel. given that the cannister also is the pathway for ventilating the fuel tank and relieving vacuum pressure as fuel is used, maybe porsche needed to do it the other way to ensure they were getting some positive pressure into fuel tank? who knows? not me thats for sure.

whatever the case porsche abandoned the system after 1973. VW kept going with theirs. and it is definitely the case that the 1.8s after the start of calendar year 74 adopt the VW system.

its a little more interesting as to what is going on during Nov/Dec 73 with 1.8s
and perhaps even more interesting as to what is going on with 2.0L cars pre Nov 73 and post Feb 74. as well as the entire range in 75. i have seen that the 75 2.0L cars adopt the fan port like the smaller engine cars for the blower feed to the can and stop using the tin-ware port on the lhs. i'd be interested to know if they also adopt the VW plumbing in addition.

Click to view attachment Click to view attachment

@wonkipop Here is my emissions control system booklet that came with the 914 when my father purchased the car.

hey thanks @L-Jet914 .

looks like yours matches mine.

from our EC research my files said your car was an april 74 car.
so this is a nov (?) 73 edition emission warranty with an april 74 car.
and i have a nov (?) 73 ed e warranty with a jan 74 car.

getting somewhere.

i found these fairly easily on ebay ads.
1975 911 glovebox handbook.
looks like porsche switch to regular numerals like VW in 75.
(or maybe they used roman numerals for 914s?).
thinking now very likely warranties are dated for publication by this number.

Click to view attachment
Click to view attachment

You're welcome. Yeah my car is 4/74 build month.

Adding to the weirdness, strange that there is a 1974 1.8,2.0 booklet and a 1974 2.0 booklet.
They show up regularly on eBay, so might be good source for 75 book info and diagram.
Will check the date in my book.
UPDATE: Yep, mine is exactly the same as L-Jet914 (though mine is MUCH more wrinkled...). "4654.23 12 400 XI/73 - Edition 74"

yes @StarBear , you noticed that too about that ebay advert i found.
i've never seen one before that is only for the 2.0.
perhaps it covers the period from aug 73 to end of oct 73 when they were only making 2,0 L cars and the 1.8 had not come on line yet? i don't know. the only clue is the description which says its ed V111 (or 8) which might equal august.
everything else i have seen is for both models, in 1975 and 1973 and generally for 1974 as well.

going back through my files i come up with this from our EC A B research.

there is 1 cluster around van's car - all very good condition examples.

----------

1973

6 dec 73

Click to view attachment

7 dec 73

Click to view attachment

10 dec 73

don't have pic of van b car but his emissions booklet implies its plumbed in version 1 layout like 6 dec yellow car.

------------

there is a second cluster of january cars all with version 2 layout.

1974

9 jan 74

Click to view attachment

15 jan 74

Click to view attachment

25 jan 74 wonki car

Click to view attachment

8 feb 74 low miles car formerly in collection of dr914

Click to view attachment

-------

the rest of the cars i have on file after this date, of those where you can get a clear view of cannister are consistent with the january cars. and match the XI 73 emission warranty diagram,

cars prior to the december cars (late oct.- 20 nov 73) have the frunk cannister.
can't really tell what they do as the hoses can't be traced from engine to frunk.
but i'm guessing they are no different to all the cars from 1970 thru 1973.

--------

once i dragged out the december cars and found the other one on file its a little inconclusive. they are plumbed up opposite to each other. both are very good condition cars. maybe one has had its can removed for clean up detailing and its gone back on differently. as to which one - i dunno. the yellow one conforms to the emission warranty @Van B has.

Here you go @wonkipop

All of those you posted are opposite mine... Looks like I may be the wonky one lol...

thanks for taking the trouble to post that up Van.
a close look at the yellow and white december cars says you kind of match the yellow one. but the can has been orientated the other way in that car.

your emissions warranty is interesting - an X. X = 10 = October?
definitely different.

sure is a can of worms.


take a look at what i found. (and @StarBear ).
i think its for the same 2.0L emissions warranty booklet i posted up at top of page 2 that is from ebay. i found an old samba listing doing an image search (which is a reasonably time efficient way to turn up old material on the net). its has the all important interior page of the booklet. the diagram of the cannister connections is as per @JeffBowlsby 's 73 diagram and the one in your booklet Van.
the edition is numbered VIII 73. VIII = 8 = august?

Click to view attachment
Click to view attachment
Click to view attachment

so far we got three different emissions warranties for 74 MY.
a VIII (exclusive to 2.0 L - probably from august to end of oct 73) = version 1 layout/frunk can
an X (covers 2.0L /1.8 from end of oct 73 to end of december? - hard to know). = v 1/frunk can-engine bay crossover
and quite a few XI types. (covers 2.0L/1.8 from at least jan 74 on). = version 2 layout/engine bay can. note still to confirm layout of 74MY 2.0s built in 1974.

the X booklet in reality probably only covers 1.8s as they appear to only make 1.8L cars between end of oct 73 and sometime around end of feb 74).

i'm thinking they are print dated a little in advance of when they end up in the cars?

Any 74 2.0 owners want to be a friend and post their data??

It’s starting to look like mine was built during the last month of this layout.

This beyond cool Wonk. You are really shredding this topic looking under every stone.

thanks jeff, i'll take the compliment but i'm counting on you to keep me on my toes.
i'm just sniffing around the 1.8s.

if we get some members to post up a 73 emissions warranty and a 75 with the hose diagrams we might be in business getting a clearer picture.

what will help seal it will be an emissions warranty known to have come with a 74 2.0L built in calendar year 74.

Happy Easter Wonki. I just remembered you live in the future lol!

thanks.
same to you guys.

.........i seem to be stuck in a time warp back in the past at the moment.

I’m pretty sure there are a few in our community that match those descriptions!

have verified "2.0L only" emission warranty weirdness you noticed steve is tied to the first batch of 2.0L cars in august-oct 73. this is a 09/73 car.
from a well dcounented BAT ad of a good condition orig 2.0L.
so VIII (8) manual is certain to be a publication date marking on the warranty.

Click to view attachment
Click to view attachment
Click to view attachment

an aside from scanning BAT ads for above - noticed something.

since our EC A and B research last year strongly suggests that 1.8L cars were exclusively produced by the factory between end of oct 73 and end of feb 74, we have stumbled on a fast test for 2.0 L fakes?

think i spotted one from an old BAT ad. looking at vin i noticed it was in the 12000 range. an 01/74 car. thought = there goes my findings on 1.8 production.. took a close look at photos. thought again. clever range of shots. only one image of engine bay. interior photos that skill-fully cropped the lhs combo dial (basic 2..0 temp guage) out of view.

last years EC engine research has a bonus for prospective 2.0 L buyers.
anything with an 11/73 to 02/74 vin number date should be looked at closely. not saying the research is 100% certain on this - but its 99%.

not a problem if a car is being honestly presented as modified.
the advert i stumbled on wasn't quite like that.

Click to view attachment
Click to view attachment

That is COOL sleuthing!!!!

Now how to make that info easy to find!?

if there were more photos of the engine bay in the ad i found it might have been possible to spot another sure fire give away. signs of the air cleaner mounting plate for a 1.8.
but no photos. just the one shot of the engine bay. lot of pink hoses.

@JeffBowlsby

since its pouring rain here and ruining my easter.
i trawled back through the file i had of stuff when we first went over this a year or two back.

i had this on chevrolet vapor emission system - dates from early 70s.

whats interesting is the interval for replacing the cannister.
only 5,000-7,000 miles.

i looked up the 914 emission warranty.
the service interval for the VW/porsche cannister in our cars is 50,000 miles - and replace can!

10 times as long.

just a thought, and usual wonki one.
wonder if vw/porsche were fan blowing the can to really supercharge it with oxygen to make sure it purged completely -----to help it last longer? trying to make it more resistant to saturation. not saying this idea worked in the long run for them but it might have been their crazy rocket scientist brainwave?

GM one is relying on induction pull from the intake manifold to draw air flow through the can after the valve opened. no extra assistance or "ve haff vayz of making you turbo charged".

i'm half german, but not much of a rocket scientist.

Click to view attachment