Switch carbs on 230/8?

Just got back from a 2,548 mile trip from Florida to Michigan & return in my '69 230/8. Non-stop on I-75 except for a visit to the Air Force museum in Dayton, OH & a stop at the MB dealer in Cincinnati. Car ran flawlessly except for a leaky clutch slave cylinder. Went bad after I replaced the master cyl. before the trip started. Was OK on the road once everything warmed up; but those 22 deg. nights in Dearborn started the seals leaking.

After 29 years in MB diesels the straight six is a pleasure in smoothness & quietness. But with that comes a sacrifice in economy. I averaged 22.51 MPG whereas a diesel would get 33 - 37 at the same avg. speed. So my question is does anyone know if I could replace the Zeniths & the intake maniford with a single Solex carb like on the 219 (105 body style)? They'e both M180 engines with the same stroke, slightly different bore. And if it could be done would it give better mileage? A manual choke would help extend engine life, too. I know it won't have the same power but just so it can cruise at 65 is OK w/me. Don't want to change the drivetrain configuration like going to a lower rear axle or a 5 spd. (has a 4 spd man now) - this small (2.3L) six need all the RPMs it can get.

I know there's other alternatives like going to Webers but I'd like to try the small Solex if it would work. Any comments? Thanks.

Cal

[Mark DiSilvestro]

As the saying goes 'there's no free lunch'.
You're getting about 1 or 2 MPG BETTER than my '60 stick-shift 220S does at modest highway speeds.

I used to have a '72 220, the 4 cylinder version of your 230, with the single barrel Stromberg carb. It only got 1 or 2 MPG better than the '72 250 6 cylinder that replaced it. Without an overdrive gear or different axle ratio, I wouldn't expect a significant MPG improvement, certainly nothing as good as your Diesel.

The simplest thing you could do to attempt a modest MPG gain would be to advance the ignition timing a couple of degrees, if that doesn't create a pinging problem. You can try to lean the idle mixture screws and reduce the idle speed slightly. When I first got my '72 220, the carb was adjusted so rich that on my first trip it only got 12 MPG!
At 22.5 MPG, it sounds like your car is running pretty close to optimum. I feel 'if it ain't broke, don't fix it'.

Happy Motoring, Mark

[Tomguy]

22.5MPG on a 1969 gas model is NOTHING to scoff at. Considering what vehicles of that era averaged, that's SUPERB mileage. That's better than any modern SUV can imagine to get, and probably only slightly lower than most modern sedans (My Intrepid gets about 25 all highway, 23 mixed). I'd be far more than pleased with that. Being that you're used to diesel, it may seem like low economy to you, but that's pretty damn efficient for a gas engine. If you REALLY want better mileage, about all that would really help is an overdrive tranny or a diesel engine. Replacing the dual carbs with a single Solex might hurt, being that you'd have less power so you'd have to "Floor it" a lot more to get it to go (although since you're used to those diesels, you might not care that it takes ages to get your speed up). The cost of replacing your setup now with a single solex (manifold, carb, misc parts) would cost you more than what you'd save in gas costs over 10 years!

[nachi11744]

Hello,
Your fuel consumption is about the best you will get out of these type of cars, the factory's listed fuel consumption for a W114 230/6 was 16l/100km, which works out to approx. 15 miles per US gallon!!
My W115 200 with a single Stromberg manages about 22mpg in urban usage and 25-27mpg on the highways at around 70-80mph with continious use of AC.
You have to keep in mind that cars like the W114/115 and BMW 3.0 and 3.0Si were designed and put into production long before there was a *Green Party* or environmentalist lobby in Germany.
They were meant to be driven fast at or near maximum power revs.
Just my 2 cents.
Have a good weekend.

[Mark DiSilvestro]

I wish my '72 W115 220 got 22 - 27 MPG.
After 1970, most US market 4 and 6 cyl gas Mercedes, includng my car, were sold with the mandatory-option automatic transmission and a 4.08 axle ratio, instead of the 3,92 or lower ratios that were availible outside the US.
At best, my 4 cylinder 220 got about 17 city and 22 highway.

Happy Motoring, Mark

[WANT '71 280SEL]

With about 80% highway miles I only get about 23.3 mpg.! You are getting the economy of my turbodiesel with the power and benefits of gas, I wouldn't complain. If I knew older MB gassers could get that good economy I would have aimed more for the fintail I originally wanted. Something like a 190 or a 220 gas.
David

[Mark V]

I had a 69 230/8, recently sold, and the driving I did was essentially combined city hiway, I'd average 15-18 mpg, when I did more hiway driving it climbed to around 21 but really no more. To do that, and to keep it driveable I had to use mid grade at least. Running regular and it ran like junk and the mileage was noticably lower.

I've been taking my new Altima on the same driving pattern and its 100% better, without dropping the pedal to the floor at lights etc. I'll get about 30mpg, I hate stopping for gas! Not the same class as the Benz, but at least I don't get the breeze from below my feet anymore.