Let me start off by saying that I know nothing about carburetors. All I understand is that they inject gasoline into the intake manifold by means of some sort of injector. Literally, that is the extent of my knowledge. I’m very thankful that I came across this forum.

I know this topic is discussed on every other thread but I'm having trouble. My 114 280C is (you guessed it) having Solex issues. I'm to the point of replacing the POS knock-off q-jet with a kit or something equally good.

What is the best/easiest/cheapest? I've read a dozen or more threads about this and I guess I’m looking for a definitive answer. I know there's a JAM Engineering kit with a Holley 4bbl and a Weber 2bbl, as much as I would prefer 4bbl unless there is no noticeable difference in performance. Is there a third option? My mechanic tried a q-jet and it does not fit plus he doesn’t want to put a used/reman. carb on. I’m ok with this. I know adaptor plates aren’t easy to manufacture so I can’t just grab any random carb off the shelf. Plus I don’t know the cfm of my M110 motor or what that has to do with carb cfm.

See? Ignorance is not necessarily bliss.

Any help is greatly appreciated, as I would like to fix this soon. I like the Holley kit from JAM the most, it is a little pricey at $985, sounds a little overpriced to me, but what do I know right? That’s mostly why I’m looking for a third option unless that’s not easy or cheaper. Thanks in advance.

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Die auto ist immer kaput...

Best. install a TBI fuel injection system. Requires a bit of work but is the most performance effective.

Easiest. Jam Engineering's Holley conversion. Most expensive but is a relatively easy "bolt-on" application. Allows you to retain the stock air cleaner and existing linkage setup.

Cheapest and most cost effective is the Q-Jet or 2 barrel conversion. Requires a bit more work and a couple of sacrifices. Linkage needs to be re-worked, loss of automatic choke function, some machining of the base plates on either the carb or the adapter plate and loss of the stock air cleaner.

Your choice. I myself have gone the Q-Jet, 2 BBL and now the Holley carb route. I was ready to install the TBI unit but fate intervened (AKA my wife's car which is getting the TBI unit). I was happiest with the 2BBL but the Q-Jet worked fine. The Holley works great but I've really got the TBI "bug".

you're forgiven, it's an obvious and necessary sin. -CTH

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- cth350@gmail.com
http://www.111lakeside.com/

You can basically duplicate the JAM setup if you can find a Holley 4360C carb. Then you need a new base gasket and some fiddling with the linkage and connections to get it to work. You need to plug the vacuum fitting in the rear and "loop" or plug the coolant connection to the choke.

If you can find the carb, you can get a kit for it from Jeg's.

Find a carb, and send me an email for details.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

The carbs, they don't ever "inject" gas unless you are punching the pedal, in which case the accelerator pump squirts some in. The gas gets "sucked" in with carbs. If you want to inject, which IS worlds better, then:

A GM TBI takes only 15psi of fuel pressure to make it work, I'd be inclined to think that the stock lines could handle that. All you'd need is a fuel pump, a junkyard TBI, and a place to mount the coolant sensor right? Oh yeah, and some kind of spread-bore to TBI plate, but I'm sure those must exist by now. ...and the megasquirt controller, and the wiring, and linkage, and cleaner... and etc. etc.. hmm, maybe not.

I'm not saying it's not worthwhile, I'd love to try it on my car, but it's definitely not an easy thing, especially for a beginner. The JAM kits are really *really* expensive, they're almost a grand before tax! I'd vote for some kind of DIY holly conversion like ctaylor described.

What would be really slick is some way of undercutting JAM and producing an easy M110 TBI conversion kit! Seems like there is some kind of demand for one. Probably not profitable though. Maybe by not including the TBI unit, fuel pump, sensors and some other easily sourced stuff.

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1967 230S automatic
Boston, MA

If someone figures out how to make an adapter plate, I have a buddy with a cnc machine that can kick out as many as you like.

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With best regards

Al

A rough estimate for the TBI conversion so far.

$300 for the Megasquirt. I don't recommend a novice to build the kit, I'm extremely experienced with circuit board assembly and I have the proper sized soldering pencils and tips. Get the version 3.00 board. It already has the "goodies" installed.

If you decide to build the kit then expect to pony-up another $60 for the Mega-Stim to check your work.

$120 for the relay board and wiring harness set. Spend the money! You can wire the relays and make a harness but it's soooo much easier and better looking.

I ended up deciding to use the Ford van electric fuel pump and mounting it at the tank outlet. $100 new or less if you find one in a junkyard, errr I mean, automotive recycler.

$20 for a GM throttle body unit. Get the two injector unit from a V-8. The unit from a mid-eighties Ford 5.0L works as well.

$45 for the sensors or free if you scavange them from the same engine you got the TBI from.

$50 to have an O2 installed by a muffler shop.

$30 for the adapter plate and gaskets.

$40 for the high pressure lines, fittings and fuel filter.

I'm sure there are a couple of other items I forgot but it's just a ballpark figure so far.

Al, I just might take you up on the offer of your friend. Let me get finished with my wife's FI conversion and I'll be back on the M110. The only difference is the TBI unit itself so the second conversion should go MUCH faster than the first one did.

Why not install a CIS-K system?. There are thousands of m110 engines sitting in junkyards with perfectly good injection systems that will bolt right on to your engine. There's no PCB assembly, no "R&D", and best of all new parts are available for future service like fuel filters etc.. If you go to a pick-your-own-part yard then you'll see how everything goes together.

I bought all the parts I needed to convert an air-cooled VW to CIS fuel injection at a junkyard for under $250.

There's a minor bit of fabrication to fit the return line from the fuel dist to your gas tank. That's very minor.

Just in case you are unfamiliar with the CIS-K system, here is a link.

http://home.hiwaay.net/~langford/CIS.html

The only advantage MIGHT be the cost. It's still '70's technology and you will be dealing with used parts.

Effective, yes, efficient ?

Be advised, the "E" (injected) series use a different cylinder head.

I being an owner of a 76 280C, must say if you are going to go through the trouble of TBI, why not go another step and do MPFI? The only harder part is welding in injector bungs into the manifold, and getting them in the right spot.

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-Randy Wakefield

1969 220D 4 speed (parts car)
1976 280C
1976 280S
1981 240D 4 speed (parts car)
1982 300D
1983 300TD (Ivory)
1983 300TD (gold)
1985 300TD (gray)
1987 190D 2.5
1970 280SEL (sold)
1977 240D 4 speed (sold)
1974 280 (rusted to death)
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1927 Chevy 4 door sedan
1938 Chevy 2 door sedan
1950 Willys Jeepster
1955 Studebaker President 4 door
1977 Ford F250
1979 Glastron 17'
1948 John Deere A
1960 John Deere 2010
1979 Satoh S650G
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2000 Bichon (Doby)

Easier installation doing a TBI.
It only requires 15-20 psi fuel pressure so the stock fuel lines are adequate. The high pressure lines I refer to in my installation estimate are for the flexible engine compartment lines and the connection at the fuel tank.

I don't know if I'd trust 35+ year old fuel lines under 50+ psi. I don't think the existing relatively small feed and return lines are adequate for the newer injectors and flow rates.

No fuel rail to build and it's reversible. That's a big plus in my book.

You still need to adapt a throttle body for the TPS.

Most TBI units already have the regulator built in.

I'm just too lazy to do all the extra work. Probably the main reason for ME anyhow!

He would have to change the heads as the CIS system injectors mount on the heads of the M110 not intake. It's a PITA to change heads.

Why not just go with a holley TBI projection system.

http://store.summitracing.com/instructions.asp?File=hly%2D199r10262%2Epdf

Another reason is a GM TBI unit is really inexpensive and available at any junkyard, the price of one injector for an MPFI setup. If you're starting with a carb, the TBI is a good first step and enough to satisfy most people. If you're starting with a stock mercedes injection setup, then obviously MPFI is the way to go.

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1967 230S automatic
Boston, MA