M30B32 + carbs?

[Ezz]

Hello gentlemen,
I have posted a thread here before asking about couple of engine options for my bavaria 2800.

Bavaria engine options E32 vs E28 M30

Hello, This is my first post here and I have been learning so much reading threads on this forum. It has been a great help keeping me motivated to restore my 71 bav 2800. The m30b28 that came with the car is seized up and missing some parts, so no point of rebuilding it. I have an engine...

e9coupe.com

However, I ended up getting an m30b32 for good price because the b35s deals did not work. The guy I bought the engine from said it came out of 1985 733i automatic.
I would like to know what you think of replacing the engine’s motronic 1.0 FI system with carburetors? I have the original 2800 manifold and zeniths. I would need to get the upper timing chain cover and distributer because my b28 is missing those two components.
Also, I would need an electric fuel pump. (Not sure what else?)
Would this be a simpler path to use carbs than keeping the motronic 1.0?
My goal is to make this engine run ok on budget. until I get a b35 and then maybe switch to Motronic 1.3 FI.

Any recommendation or advice is much appreciated.

 

[Ezz]

And here some pictures showing the condition of the carbs I got. They do not look good and not sure if they are worth rebuilding…

 

[Ohmess]

According to two of our engine gurus, the M30b32 engine you have acquired is a very good engine:

https://e9coupe.com/forum/threads/4310316-begins.21172/post-370012

https://e9coupe.com/forum/threads/4310316-begins.21172/post-370013

I know TodB has one in his coupe and likes it a lot.

I have not done a fuel injection to carburetor change, but I would think keeping the fuel injection system on the engine you acquired would be much simpler. And those carbs look like they need a lot of work.

 

[Ezz]

Thank you for the reply!
Few things that made me reconsider carbs are the intake interference with brake booster
And the speed sensors for the motronic 1.0 do not work with the manual fly wheel i got and the getrag 260 bell house doesn't have the holes for the sensors (can be drilled).
I have all the hardware to do a motronic 1.3 conversion except that the ecu is from a b35 engine which as far as I read it wouldn’t work properly due to different compression ration and displacement between b32 and b35.

And the last thing is to retain as much as possible of the original classic setup of the car.

 

[Ohmess]

Did BMW sell an m30b32 with motronic 1.3? If so, you should be able to find a 1.3 brain for your engine out there. If not, I wouldn't try to implement an engine management system BMW never used on that engine.

 

[Mike Goble]

Every motor I've had in my E3 has been swapped to carbs. It's pretty basic. How much of the original engine do you have?

 

[stphers]

I have a set of carbs and intake manifolds that I have restored ready to be put together that I would sell PM me for more info if interested

Thanks, Rick

 

[Ezz]

Every motor I've had in my E3 has been swapped to carbs. It's pretty basic. How much of the original engine do you have?

Hi Mike,

I have #1,2,3,&5
I am missing #4,6 and the upper timing chain cover. I do have the worm drive that attaches to the camshaft but not sure what I need to make fit the b32 camshaft.
I also have the mechanical fuel pump but that is not going to be useful i think.
I might have read somewhere that I need the original engine thermostat housing to clear the carbs but not sure if I miss read that or confusing things as I have been doing a lot of readings. Anyways, i have that too.

 

[Ezz]

Did BMW sell an m30b32 with motronic 1.3? If so, you should be able to find a 1.3 brain for your engine out there. If not, I wouldn't try to implement an engine management system BMW never used on that engine.

Hi Ohmess,
I do not believe BMW made a b32 with 1.3.

 

[Ezz]

I have a set of carbs and intake manifolds that I have restored ready to be put together that I would sell PM me for more info if interested

Thanks, Rick

Hi Rick,
PM sent.

 

[Ezz]

I also want to note that my Bavaria is a 1971

 

[HB Chris]

You don’t need 3, 4 or 5 either, just smog related stuff. Remove that wiring to/from the box (speed relay) and vacuum hoses.

 

[Ezz]

You don’t need 3, 4 or 5 either, just smog related stuff. Remove that wiring to/from the box (speed relay) and vacuum hoses.

Even simpler….Thanks Chris!

 

[Ohmess]

As to fuel pump, the head on the M30b32 likely won't have a place to mount it. You will need to install an electric pump. I suggest looking at this thread: https://e9coupe.com/forum/threads/adding-a-electric-fuel-pump-suggestions.42221/post-369474

I think you need this nut to mount that distrubutor drive gear to the cam in your motor: https://www.ecstuning.com/b-genuine-bmw-parts/hex-nut/11311284801/ Double check this with Don Lawrence (sfdon).

As to carburetors, I think you have a couple of options. First, you could perhaps rebuild the Zeniths you have, but they don't look great.

Second, you could hunt down a set of Zeniths that are in good shape. Loks of people took these off their cars, so there are probably some around. I gave away a pair last year. If you go this route, however, you probably want to hunt down the BMW tuning data for the 3.3L, which used the M30b32. Zeniths tuned for a M30b30 may not work well on a M30b32.

Then there are the Weber options. You can mount downdraft Webers on the stock intake manifolds, with adapters. The 32/36 DGAVs were popular; I had these on my coupe when I bought it. For the b32, however, I would think a set of 38/38 DGAVs would be preferable.

Lastly, you can go with sidedraft Webers (either DCOEs or DCOMs). Usually, these are a fair bit more expensive. Not only would you be buying three carbs v. two, but you need different intake manifolds, and with these, you may run into issues with both the thermostat housing and with the brake booster.

I'm pretty sure I have a front timing cover and a distributor in you need them.

 

[Ezz]

As to fuel pump, the head on the M30b32 likely won't have a place to mount it. You will need to install an electric pump. I suggest looking at this thread: https://e9coupe.com/forum/threads/adding-a-electric-fuel-pump-suggestions.42221/post-369474

I think you need this nut to mount that distrubutor drive gear to the cam in your motor: https://www.ecstuning.com/b-genuine-bmw-parts/hex-nut/11311284801/ Double check this with Don Lawrence (sfdon).

As to carburetors, I think you have a couple of options. First, you could perhaps rebuild the Zeniths you have, but they don't look great.

Second, you could hunt down a set of Zeniths that are in good shape. Loks of people took these off their cars, so there are probably some around. I gave away a pair last year. If you go this route, however, you probably want to hunt down the BMW tuning data for the 3.3L, which used the M30b32. Zeniths tuned for a M30b30 may not work well on a M30b32.

Then there are the Weber options. You can mount downdraft Webers on the stock intake manifolds, with adapters. The 32/36 DGAVs were popular; I had these on my coupe when I bought it. For the b32, however, I would think a set of 38/38 DGAVs would be preferable.

Lastly, you can go with sidedraft Webers (either DCOEs or DCOMs). Usually, these are a fair bit more expensive. Not only would you be buying three carbs v. two, but you need different intake manifolds, and with these, you may run into issues with both the thermostat housing and with the brake booster.

I'm pretty sure I have a front timing cover and a distributor in you need them.

Thank you great info! I am first pursuing the zeniths if I can find a set with reasonable price. I could attempt rebuilding the ones i have but there is a lot of corrosion and some of the valve screws stuck.

I am interested in the distributer and cover
I will send you a pm.

 

[Bert Poliakoff]

Did BMW sell an m30b32 with motronic 1.3? If so, you should be able to find a 1.3 brain for your engine out there. If not, I wouldn't try to implement an engine management system BMW never used on that engine.

1.0 fuel injection was pre '82 injection system Unless I am wrong, what you have is Motronic 1.1

 

[Ohmess]

1.0 fuel injection was pre '82 injection system Unless I am wrong, what you have is Motronic 1.1

Hi Bert - sorry, as I noted above I am not a fuel injection person. I have triple Webers on my coupe.

The point I was hoping to make was that BMW did not sell M30b32 engines with the version of the engine management system that Ezz is hoping to use (Motronic 1.3), and because of this, I would not attempt to implement that engine management system.

Fortunately, it appears Mike Goble's summary of his experience has changed things and we are now talking carburetors.

 

[boonies]

Thank you great info! I am first pursuing the zeniths if I can find a set with reasonable price. I could attempt rebuilding the ones i have but there is a lot of corrosion and some of the valve screws stuck.

I am interested in the distributer and cover
I will send you a pm.

FYI, I just posted a set of Zeniths in the parts section

 

[Bert Poliakoff]

You don’t need 3, 4 or 5 either, just smog related stuff. Remove that wiring to/from the box (speed relay) and vacuum hoses.

In AZ if a car is 1980 or older, it doesn't have to be smogged. In addition, if you have classic car insurance, regardless of the age and you don't need to be smogged either.
I am thankful for that as my "81 E24 with a "warmed" engine would never pass.

 

[Ezz]

Hello again,

I have some progress to share and would like your feedback.
But first, I would like to thank you all for your support and for sharing this wealth of knowledge. It has helped me tremendously and I learned a lot!

So far I think I have all of the major components (some are on the way) to do the Motronic 1.0 to zenith carburetors swap.
1. Used set of carbs
2. Distributer should be on the way soon (thanks @Ohmess)
3. Distributor camshaft nut adapter.
4. upper timing cover and matching valve cover from. (Again thanks @Ohmess for pointing out the Motronic valve cover mismatch to the old style upper cover.)
5. ignition wires from Ireland engineering.
6. Gaskets thermostat, water pump…

Now the engine: (I should have listened to @sfdon before and got a good b35…but here I am stuck with this $300 b32 for now)

Did compression test and results were not good as I found a difference of up to 50psi between cylinders. Shame on me for trusting the guy and not testing it myself…
I then put compressed air through the spark plug holes and found that the air was escaping through the intake valves for some of the cylinders. (of course, I was rotating the engine so valves are in closed position).
On some of the other cylinders the air was escaping from somewhere else, could it be stuck piston rings because engine was sitting for a while?

That's said, I removed the cylinder head and here are my notes on it.

1. Each head bolt had a crisp crack sound when I was opening them. And none of them felt loose.
However, the intake side head bolts looked a lot cleaner than the exhaust ones. Is this normal?

2. Valve cover off pics

This bolt was loose:

3. Cylinders. No ridge at the top of the cylinder fingernail does not catch on it.

The surface is not rough but just looks bad.

I have not opened the bottom end yet for piston and crankshaft inspection. Sometime this week I will take it a part. Also, I will be cleaning up the head to inspect for cracks. I am really hoping that the crankshaft is in good condition and reusable without machining.

Anyways, if this engine turns to be too broken that it isn't worth the rebuild, I can still use the items I bought for the carburetor setup on another engine.
Sorry for the long post and happy Monday!