Pondering carburettor options

bizz · Post by **bizz** » Fri Jun 14, 2013 12:56 am

Hi all,

Given my leaky Zenith's I am considering three options in replacing them.

1. Triple Weber 40DCOE
http://www.piercemanifolds.com/ProductD ... tCode=K208

2. Twin Weber 38 DGAS
http://www.piercemanifolds.com/ProductD ... de=K210-38

3. Fuel injection

I'm leaning towards the second option as it's more simple/logical for my application, has anybody used these carbs before?

I am tempted by the triples, but I feel they would be overkill on a stock engine.

Fuel injection would be great, but I think this would be too much work - can anybody point me to a good resource for Carb --> EFI conversions on E12's?
This link is broken unfortunately (http://www.bmwcsregistry.org/Technical/ ... rsion.html)

thanks,
Ben

Falkenberg · Post by **Falkenberg** » Fri Jun 14, 2013 2:35 am

There are replacement kits with weber, indeed. Found also this one:

http://www.carid.com/1976-bmw-3-series- ... 26208.html

http://www.ebay.com/itm/BMW-E3-with-M30 ... 0414268892

If I had the money..

For now I have to stick with the zeniths, planning to buy some overhaul gasket sets.

bizz · Post by **bizz** » Fri Jun 14, 2013 9:46 pm

Thanks for the links

My car has been at the mechanic this week and he's managed to get them running quite well. The chokes are shot however & he suggests they need overhauling.

We came to the consensus that a set of 32/36 DGAV carbs with the manual choke will be the best option. I'll let you know how I go with this

Mike W. · Post by **Mike W.** » Sat Jun 15, 2013 12:27 am

I converted my E3 to L-jet back in the early 90's, long before I had internet access. The car was a daily driver and it just transformed it, it was a thousand times better to drive to work and the grocery store. Lost some torque, lost some MPG, got a little top end but the car was just so much nicer to drive. Turn the key on cold winter mornings and it starts, without pumping the gas pedal 3 times, not 4 or you will flood it, it just starts and idles. My wife did miss the Woooooooo sound when the secondaries opened up, but not the bucking in parking lots. If it's a weekend car, it's not that big a deal, if you DD'ing it, it is a big deal IMO.

FI is some work, but not that difficult. I had one wire out of place when I converted mine and it ran super rich, after I corrected that I had no problems with the FI as long as I had it, which was probably 5 years or so.

Falkenberg · Post by **Falkenberg** » Mon Jun 17, 2013 4:07 am

I agree, FI does add a lot from a civilization perspective. Imo, Coolest thing about motronic is to be able to start the car on a winter morning at -15 Celsius just to see how it immediately idles at 800 - 900RPM.

But I've also seen conversions gone nightmare, because right now a lot of the source l-jet systems are quite old, badly maintained, improvised, misunderstood. At least around here.

bizz, why manual choke? You will need to add some kind of mechanism to operate it from behind the wheel. E12 518 had manual choke, maybe you can source the linkage from such a car.

bizz · Post by **bizz** » Mon Jun 17, 2013 6:28 am

The mechanic who checked out my zeniths has had bad experiences with the auto choke on the webers. I like the idea of being able to control the choke differently during summer/winter months too.

One less thing to go wrong I suppose.

I'll grab a universal cable/bracket to control the choke from the cabin

DerSchwede · Post by **DerSchwede** » Tue Jul 09, 2013 12:05 pm

My 2c:
Invest half of the sum for new Webers in your existing Zeniths and get a setup far better than any FI conversion would ever bring. Perfect set up Zeniths are a cream!

AND if properly set up, you only have to push the accelerator pedal once before you start, no matter if it's -20C - works beautiful!

bizz · Post by **bizz** » Wed Jul 17, 2013 8:23 pm

I bought the webers. $600.

I will be installing them next week.

Plan is to rebuild the Zenith's as an exercise when I have time. I agree that when they're setup & working they are great!

Falkenberg · Post by **Falkenberg** » Wed Jul 24, 2013 1:46 am

Which webers? DCOE?

bizz · Post by **bizz** » Thu Jul 25, 2013 3:16 am

Got a set of Weber DGAV 32/36

Crazy simple to setup. Initial test drive is promising with better acceleration than the Zeniths and MUCH better top-end

Mike W. · Post by **Mike W.** » Thu Jul 25, 2013 10:01 am

bizz wrote:Got a set of Weber DGAV 32/36

Crazy simple to setup. Initial test drive is promising with better acceleration than the Zeniths and MUCH better top-end

I think that's the best everyday carb solution. I am somewhat surprised at the performance upgrade, my impression was they were more a reliability/driveability upgrade rather than a performance one. The evil Zeniths made good power with good economy but were terrible to live with.

bizz · Post by **bizz** » Thu Jul 25, 2013 7:38 pm

I think the Zeniths were running that poorly (air leaks everywhere) that it feels like a performance upgrade. I toyed with rebuilding the Zeniths, but I think i've made the right decision - the webers are far less complicated, brand new & bolt on. Perfect.

Falkenberg · Post by **Falkenberg** » Thu Jul 25, 2013 11:27 pm

That does look nice!
I was reading on your blog that you need to modify the airbox. Howcome? I thought the set was completely compatible.

bizz · Post by **bizz** » Thu Jul 25, 2013 11:35 pm

So did I!

I need to take a picture, but the adapters they supply are too tall & the filter housings hit don't seat onto the carbs

Plan is to modify the mounting points on the air filter housing to allow it to sit lower.

Jeff Dennis · Post by **Jeff Dennis** » Fri Jul 26, 2013 9:50 pm

That looks nice I'm thinking of switching from the FI to a single carb set up.