Firstfives.org

My car has a 3.5l bottom end and a solex 4 bbl carb(bought it that way). it is showing alot of signs of running to lean and i am thinking of what would be the best option for replacing the carb with something that can handle the extra displacement and something alittle easier to tune, and more common parts wise.

Im new to these old bmw's and appreciate the knowledge and patience.

Welcome!
Peeking out from my small shade tree, I can say that Weber has a carb that's easy to tune, and is reliable.
The progressive linkage set-up might be the best, but, I don't know what size works for your car.
I have a 32/36 cfm progressive linkage down draft Weber on my '73 '02 & it runs very well on all fronts.
On my '67 911S there were factory installed, two triple throat Webers that were wonderful!
There is also, a triple, single throat side draft Weber situation available, but, that may too radical for what you're looking for?
That set-up is usually for racing or hot doggin'!
Then, you should get at least a semi-tuned exhaust system.
Good luck,,,,Greg
Ps,,,,Google Weber Carbs. There's a phone # too.

Agreed with Greg - weber all the way.

You'll need to ditch the solex manifold and hunt down either a twin manifold setup from an early 525/528 - then mount a set of 32/36 or 38/38 carbs to them, or go all out and grab a triple DCOE 45 setup which can be purchased with manifolds/linkages etc. for a small fortune.

I have the 32/36 on my 528 and they are a dream, easy to setup/maintain/tune and cheap as chips!

Worth considering an EFI upgrade if you can't find a cost effective carb option.

thanks for all the great info guys, so i should stay away from a single 38/38 weber on the solex manifold im assuming, sonds like next adjective is to find a manifold...

Mikey; google 'Webercarbs.com' for info. They might even guide you to the manifolds you need?
Also, try & find some BMW racers, any way you can.

Oh yeah, page Jeff @ 'Odometergears.com' on this website through his PM. He races his E12.
We'll help if we can, but, please do your own research.
And, please post your where-a-bouts & what year car in your signature.
Good luck,,,,Greg

thanks everybody for the great info this is a great forum , i did find some options before i asked , just wanted to here what works from people who own the cars not selling the parts.

I like your approach to your situation.
These people are full of info & want to help!!
Don't forget to check with Jeff. Other people may chime in too.
Greg

4Bbl cars aren't my specialty, but I've heard Quadrajets will work with a minimum of problems. I have not verified it myself, but it might be worth investigating.

i found a self tuning fuel injection kit designed for old Jeeps very very tempting but pricey....

I'm putting a Q-jet on my m30b35. I have the Solex carb and manifold and about 15 Q-jets, so it's a no brainer for me. The first and most obvious modification is the mounting bolt pattern. You have to redrill two of the holes in the Q-jet base to get it to mount right, but there's plenty of metal there.

If you want to buy a carb, Jam Engineering has a Holley kit they sell for $900 or so. I could built 20 Q-jets for that money.

Here's a link to a guy who adapted a small Holley carb:
http://www.seniorsix.org/faq/2_4bblconv.html

cool thanks for the info!

Dove in and replaced the Solex 4bbl with a Holley 2bbl 350cfm carb. used an adapter plate and took alittle messing around to get the linkage to hook up.

Aside from adjusting the idle mixture the car runs like it is new right out of the box.

OTHER NOTE , HAD TO SPACE THE REAR OF THE HOOD UP TO CLEAR AIR CLEANER.

all in all a pretty cheap option to get it running .

Sorry to chime in so late Mikey see you found a way to resolve you carb issues and I'm glad to hear the 2 barrel Holley works well.

I have a solex 4 barrel manifold and will be putting on one of my Ljet cars this summer. I was considering the Holley 390CFM 4 barrel but it is pricey at $450. The e9 guys use this set up....

I would imagine that 4 barrel should work well, i went with the 2bbl 350cfm because i wanted simplicity and good throttle response because i use the car for rally cross. It has great low end and mid-range power/response, feels fuel injected, but trails off high rpms, keep in mind my car is a 3.5 liter.

A little larger 4bbl should work nice i presume...