E3 carbs in an E9

hdavis

hdavis

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Hi all,

I did a search but did not find a definite answer, so I decided to ask:

Background:
My 1972 E9 CS was at some point converted to a CSi. Even thought the conversion seems to a desirable one, and it seems to be well done, the car has never really run as it should, power is not delivered smoothly, it has "flat spots" under acceleration and doesn't idle well. I have tried the usual fixes of course, checking (and changing) all ignition components, trying electronic ignition, changed the fuel pump, filters, etc. It runs worse when the A/C is turned on. I've had the car for 15+ years.

Enter an E3:
I now have the chance to buy a decent looking E3, that is very well sorted out mechanically, and I'm wondering if I could use the E3 fuel delivery system, including the carbs to return my E9 to a CS, ditch the fuel injection (put it in the E3, and then see the E3). Would you say his is straightforward? Or will I be missing some items? I will of course spend some money paying someone to do the swap, and maybe loose some in the E3 sale, but probably not too much $.

See pic of the E3 engine

I'd appreciate your comments

Thanks

Henry

PHOTO-2024-09-05-13-17-26.jpg
 
I, personally, am a big fan of the Zenith carbs. When they are completely sorted out and adjusted properly, they work well, give ok fuel mileage and are fairly dependable. my .05 cent worth ( inflation ) And I think they sound cool when cracking a pair open throttle

Thanks, Rick
 
How does the E3 run? Does it run like you want your E9 to run?

Which Bosch injection system was added to your E9?

What carbs are on the E3? Zenith or Webers? If Webers. which model? If Zeniths, are all the original electrical devices present?
 
Thanks to both of you,

Dick makes some very interesting points. I still need to drive the car, and it has Zeniths (I also need to check on the electrical devices).

I need to double check the injection in my E9, but I'm fairly sure it's D-Jet.
 
The E3 Club's former president always recommended to leave the carburettors with the engine as there are so many different versions. That said, I see it is not possible here. Zenith for E3 & E9 were usually identical when engine/gearbox combination and country specification and model year were identical. If your 3.0 CS is a USA version and has the original engine, apart from the injection gear, then the original Zenith from a Bavaria the same age and same gearbox might work fine.

Zenith up to about 1975 have two heating systems, an electrical one and another with a coolant circle. The latter was dropped on later ones. From about September 1973 there is an additional internal air circlulation and different cold start gear. I still have not completely understood the Zenith. Were they a watch, they'd be called <<grande complication>>. Yet I like them very much.
Looking at the picture, the heat deflectors on top of the exhaust are the older version. Don't know exactly, probably not younger than 1973 which may be a good sign. On the other hand I see a vacuum box at the rear of the engine, not sure where it is connected or if at all. That box appeared quite late on Euro versions, maybe 1975. Perhaps USA versions got it earlier. The distributor is the early version, you will need it. D-Jetronic cars have their own special distributors.

Whether the D-Jetronic will work or not in the E3 is something else. There are lots of small parts hardly anyone checks, and none of them were built to last 50 or more years. As an E3 guy I would leave and use a nice running E3 as it is and try to get rid of a problematic E9. You seem to be an E9 guy so this may be not an idea you like.

Lastly, I could not stand seeing your record of 150 messages and zero likes. I do like the idea to return an engine to Zenith carburettors.
 
Thanks for your input (and for the like!). Obviously I have a LOT to learn about Zenith carbs... I initially thought these would be more of a "plug and play" kind of carb (i.e. Weber), but I see it's not that simple.

I'll keep you posted regarding what I decide to do.

Henry
 
It's easier to swap back to Zeniths than the other way around! All you will need is already there.
 
bluecoupe30! said:
Hey Henry, I have a set of Zeniths still mounted on manifolds, that I would part with, if that is of interest. Let me know and I can get some photos to you. Mike
Click to expand...
Thanks Mike, I have to dig a little deeper to understand all that I'd need to change (a distributor was mentioned for example). I will keep you in mind in case I decide sourcing the parts is a better option

Henry
 
surprised ! thats a tasteful color combination in that e3 engine,
i guess if the blue touch came from the silicone cables, and spreaded the blue infection to other parts...just an observation


on the issue
i have been around cs and csi models; i prefer zenith CS because i know a bit about how to handle and fix them, and i feel that after a good process they work nicely, the car is powerful and i can rely on my own expertise to maintain them

for many years it was easy and cheap to find replacements because many people were offered to swap their zeniths fro anything else

i agree with stevehose that back to zeniths may be easier, to me is a question of two manifolds, and two carbs, and a couple of electrical connections, but we need to take a look to your distributor too, not to mention the fuel pump.

i can not understand your plans, build a better e9 removing parts from the e3 ? well it depends on the price, but maybe is better to source the bits for your e9 elsewhere, noone can tell you that the e3 bits are shot or good



could you share some pics of your e9 engine ?

- cyl head
- distributor

Christoph said:
The E3 Club's former president always recommended to leave the carburettors with the engine as there are so many different versions. That said, I see it is not possible here. Zenith for E3 & E9 were usually identical when engine/gearbox combination and country specification and model year were identical. If your 3.0 CS is a USA version and has the original engine, apart from the injection gear, then the original Zenith from a Bavaria the same age and same gearbox might work fine.

Zenith up to about 1975 have two heating systems, an electrical one and another with a coolant circle. The latter was dropped on later ones. From about September 1973 there is an additional internal air circlulation and different cold start gear. I still have not completely understood the Zenith. Were they a watch, they'd be called <<grande complication>>. Yet I like them very much.
Looking at the picture, the heat deflectors on top of the exhaust are the older version. Don't know exactly, probably not younger than 1973 which may be a good sign. On the other hand I see a vacuum box at the rear of the engine, not sure where it is connected or if at all. That box appeared quite late on Euro versions, maybe 1975. Perhaps USA versions got it earlier. The distributor is the early version, you will need it. D-Jetronic cars have their own special distributors.

Whether the D-Jetronic will work or not in the E3 is something else. There are lots of small parts hardly anyone checks, and none of them were built to last 50 or more years. As an E3 guy I would leave and use a nice running E3 as it is and try to get rid of a problematic E9. You seem to be an E9 guy so this may be not an idea you like.

Lastly, I could not stand seeing your record of 150 messages and zero likes. I do like the idea to return an engine to Zenith carburettors.
Click to expand...


all yes to this, and also you can see air filter has the older tabs to close the lid, so i would say <73 sure
 
Thanks, you make a good point that sourcing the parts might be cheaper and easier than buying another car, someone else already pointed that out.... My idea is to built a better E9, and when I saw the E3 for sale I reasoned that all the parts are already there (hopefully), and it would be fairly easy to swap, but it might not be the best way to go.

I don't have picture handy of the E9 engine, I will take some and post them later

Henry
 
Christoph said:
I see a vacuum box at the rear of the engine, not sure where it is connected or if at all
Click to expand...
This looks like the pollution/emissions system which prevents abrupt closure of the carburetor throttles by slowing it down to a few seconds. I think this was introduced in the USA maybe in 1973 .
 
hdavis said:
Are you talking about the windshield washer reservoir or the coolant reservoir. Why does it seem odd to you? Both are the same as what I've seen on other cars
Click to expand...



"Both are the same as what I've seen on other cars"
Click to expand...
you must look more in detail,



coolant,

not same as CS, see



1725683993370.png




yellow big hose should be at orange position, you can clearly see that orange point has been closed with a welded cap

green inlet is odd to me, not present in a CS



- to make a CS car you need a different reservoir
 
Last edited:
the battery drama:


1725684369821.png



i can not see any sign of polarity in those terminals, but based on the red cable i would say that positive is at the right side,

then in blue i have marked what the negative terminal seems to do with that black cable, pretty odd as the normal way is to go like the green line, straight to the body

the red cable arrowed in red too seems to go towards the starter, which is normal, but then a second black cable heads from the right hand side of battery to the body

making this impossible to understand to me

is that battery standard, i mean positive at RH and negative at LH ?

is your car negative to ground, or positive to ground ?

in a 50 y.o. car everything is possible
 
deQuincey said:
the battery drama:





i can not see any sign of polarity in those terminals, but based on the red cable i would say that positive is at the right side,

then in blue i have marked what the negative terminal seems to do with that black cable, pretty odd as the normal way is to go like the green line, straight to the body

the red cable arrowed in red too seems to go towards the starter, which is normal, but then a second black cable heads from the right hand side of battery to the body

making this impossible to understand to me

is that battery standard, i mean positive at RH and negative at LH ?

is your car negative to ground, or positive to ground ?

in a 50 y.o. car everything is possible
Click to expand...

The positive is at the right side with the red cable going to the starter as you mention. I have to check where the black cable (from the positive) goes, it doesn't go to the body I can assure you that, it must be powering something else.

The ground or negative cable is easier to explain. I have a battery cut off switch installed in the left hand compartment (where the hood opening handle is), so that's why the ground cable doesn't go directly to the body. It goes from the battery to the cut off switch and then to gound.

Not only is this a 50 y/o car, but one that was messed around with in the 90s when it was converted to a CSi. Add to that the fact that I am in in Mexico, and there's probably less than 10 E9s in the country, so I have nothing close by to compare it with....and there are no mechanics that have specific knowledge of the E9.

I appreciate you pointing these things out so I can investigate and return to original whenever possible.

Same story with the water tank, I never realized it was incorrect or modified, now I have one more thing to fret about... ;)

Enjoy the weekend!

Henry
 
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