1972-1981 (E12) knowledge base

[JKuhn]

Basically, yes. Just beware that you'll likely get drone.

[Bibiguy97]

I there anyway i can add more hp to the m30b28?
other than turbo or supercharger

[JKuhn]

Basically you need to get more air into the cylinders, or increase compression. So gasflowing the head will help, along with the cam(s), stuff like that. You can also get more power from the bottom end (higher compression pistons, longer stroke, stuff like that), but most of the power potential is in the head. Fair warning though, gettting power out of NA can get very expensive. The cheapest and quickest way is to play with the ignition timing, but be careful not to get knock.

[Bibiguy97]

Hello again i was just curious to know if we can modify the ecu of the m30 is it possible?

[DarkSideofWill]

I there anyway i can add more hp to the m30b28?
other than turbo or supercharger

Remove it an install an M30B35...

[JKuhn]

Hello again i was just curious to know if we can modify the ecu of the m30 is it possible?

No idea, sorry.

[e12Euro]

Hello again i was just curious to know if we can modify the ecu of the m30 is it possible?

The L-jetronic fuel injection is an analog system, its parameters are factory set. The later Motronic systems allowed you to replace a removeable "chip", with one programed differently, usually sacrificing torque for more top end power. Converting to Motronic isn't easy, you need a lot of parts, a different wiring harness, and the later M30 blocks are a little different. Not really worth doing. The early Motronics were advanced for their time, but primitive compared to a modern aftermarket injection system, which can be programed for more power. However, all this should be done with a sportier cam, gas flowed head, higher compression ratio etc. There is no quick, cheap way to more power.

The first entry on the firstfives site, goes through all the steps of swapping a 2.8 to a 3.5L

3.5 conversion

Replacing the standard log type exhaust manifold, with a less restrictive flowing set of tubular headers, will pick up some power. Tubular headers really only suit a left hand drive car, because otherwise the steering column is in the way. That's why BMW used the restrictive set up, so it would fit LHD and RHD cars, especially RHD cars with factory a/c.

Your engine problems sound like a vacuum leak, which can come from various sources and cause the motor to run lean and gasp for air, or run rough. I know you did an engine swap, and to get a good seal, you needed new gaskets for the intake and exhaust manifolds. If the leak from a poorly sealed gasket is bad enough, it can cause an engine to just flat die out. It's sucking in too much air. The L-jet computer doesn't know about this because it calculates the air fuel mixture mainly based on throttle position and the moving Air Flow Meter (AFM) flap.

[Bibiguy97]

I have a problem...the rpm is playing as if the the choke is running from 900 to 200 rpms even when it is at normal temperature
And when i fuel up the car just chokes as if the spark plugs need changing any ideas?
Might it be the exhaust system? I still have my old m20b20 exhaust

[JKuhn]

You mean when you open the throttle? Sounds like your injection system isn't right, but I can't give any usable pointers there as I don't know the system. Doesn't sound like an exhaust issue to me.

[Bibiguy97]

When idling when i open throttle all hell comes loose but its when idling as if it chokes and when i refuel it feels like a spark plig that is disabled but when i start driving it fades away

[JKuhn]

So when you refuel it you get issues...

Does the car have some manner of evaporitive emmissions system? That's all I can think of.

[Bibiguy97]

Ok so it was a problem with the fuel injection i got it fixed but the more i fix the more problems appear....now i have a rattling noise in the engine....in high rpms 4k+ its appears like a grinding noise from the upper engine...thats where most of the sound is from

[DarkSideofWill]

Pull the cam cover and look?

[bmw emw]

hi guys , need your help!
early e12/b25 euro , the indide door covers and panel of gauges is fit from e12 second generation ? and front fenders hood and tailgate interchangeable?

[JKuhn]

I'm not sure what you mean. Are you asking if you can install those components from a facelift E12 on your prefacelift E12? If so, I don't see any reason why not. Do you want to intstall parts from a second gen 5 series (E28)? If so, some might fit, others not. In South Africa we had the E12/8, which was basically an E12 body with an E28 interior.

[Bibiguy97]

Hello guys i just bought an e12 for my brother with the m30b28 engine of the e28.
When i floor it and take my foot off the gas (decelerate via engine braking) lots of smoke come out of the exhaust like lots and lots of smoke and get in the cabin
Please help please🥺🥺

[DarkSideofWill]

Black, blue or white smoke?

[Bibiguy97]

I think its white smoke picture it as if you were seeing smoke from industrial factories, but white lots of smoke

[DarkSideofWill]

White smoke tends to be coolant, which usually means head gasket (or cracked head or block).

Since it's doing it on coast down when there's vacuum in the manifold and cylinders, that's another indicator of head gasket problems.

[Bibiguy97]

Is it that bad? I bought the car in great shape the engine was running smoothly and you cant even hear a rocker sound. My brother is in the military i wanted to surprise him but it only showed up after brutaly driving it. So that means i have to rebuild the engine huh?

[DarkSideofWill]

It means you need to get a compression or leak down test to verify, but white smoke on overrun strongly indicates head gasket.

[Capnophobe]

I’m actually looking to purchase a 79’ 528i with 200,000 miles on it, it’s selling for $5900 and the interior is in immaculate shape, I’ve just been trying to find info on the cars and get a grasp on how difficult and expensive parts will be, what maintanence is common around these miles, the owner says it’s perfect but I’m new to bmw (not to german cars) and I just want to know all I can about e12’s and 528i’s so please hit me with any and all info you can, thank you!

[e12Euro]

I’m actually looking to purchase a 79’ 528i with 200,000 miles on it, it’s selling for $5900 and the interior is in immaculate shape, I’ve just been trying to find info on the cars and get a grasp on how difficult and expensive parts will be, what maintanence is common around these miles, the owner says it’s perfect but I’m new to bmw (not to german cars) and I just want to know all I can about e12’s and 528i’s so please hit me with any and all info you can, thank you!

They are pretty rugged cars, but check the cylinder head is ok, if the oil spray bar under the cam cover is still spraying (can get clogged if oil changes are skipped), check the condition of the diff mounting to the trunk floor (all nice and secure).

read following article and join firstfives.org

1977 528 Auto p1

1977 528 Auto p2

1977 528 Auto p3

[LazyE12]

Hey y’all! I know there’s not much on the E12 thread, but I’m picking up a 81 E12 5spd in a couple weeks. The brake booster needs replacing, is there a guide in which to do this properly. It’ll be my new daily since my subaru is just a liability.

[e12Euro]

Hey y’all! I know there’s not much on the E12 thread, but I’m picking up a 81 E12 5spd in a couple weeks. The brake booster needs replacing, is there a guide in which to do this properly. It’ll be my new daily since my subaru is just a liability.

Hi LazyE12, these pages are from the Haynes repair manual.