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Old 12-09-2002, 10:06 PM
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small block chev into a 85 126 chassis

I like my 380 SE, however I have so far changed my right hand cam and rockers, water pump, looking into changing my timing chain, scared that I'll eventually have to change my fuel injection pump, so, economically speaking, a small block Chev you can find parts for them a dime a dozen. But I want to keep my Mercedes because the body, transmission and rear end are sound. I'm spoiled by the interior. So, has anyone attempted to put a small block Chev into an 85 Mercedes 126 chassis???
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Old 12-10-2002, 01:32 AM
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Location: NW Indiana LaPorte
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now that you've blasfemed the big MB i suggest you keep a look out both ways when crossing the street and your eyes on your back cause i hear tell that some of these guys have luted and plundered for less than suggesting a gm product in a mb.

oh the shame of it all
Thanks Much!

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Old enough to know better but stupid enough to do it anyway!
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Old 12-10-2002, 01:49 AM
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I would like to see you do this. I have seen small block Chevys in a lot of vehicles. I have seen on in a SL and have seen a couple of Rolls Royce and Jaguar, the Jags and Rolls parts are EXPENSIVE. The only thing that concerns me is the time in fabricating the mounts and such may be more expensive than replacing the engine. If you can fabricate the parts yourself and enjoy a long project, it would be okay.
1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
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Old 12-10-2002, 07:51 AM
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Yes, this is most definitely MB blasphemy of the highest order. Yes, parts are a dime a dozen for an SBC. Just goes to show that you get what you pay for.

If you are bent on swapping in an American V8, however, there are several comments I will offer. To begin with, you mentioned that your transmission is in good condition. If you are thinking of mating it with a non MB engine, forget it! You will be much better off using a transmission from the manufacturer that makes the engine.

Secondly, if you want an American V8, the SBC is one of the worst choices for the 126 or most any other MB chassis. This is because the oil pan sump is on the REAR of an SBC, while the MB engine has a front sump. What goes along with this is the fact that the distributor is in the rear too and will be a real problem to fit against the firewall. A small block Ford would be a better choice due to its front distributor and front sump.

If you plan on doing ALL this work yourself including rebuilding and preparing your own engine, fabricating mounts, doing all the jillions of wiring and plumbing changes, and you really watch your budget you MIGHT be able to accomplish this for less than it would take to properly rebuild your MB V8. If you must have this work done, you are entering into a project based on false economy.

In any event, your end result will be a noisy, relatively rough running engine.

Good luck,
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Old 12-10-2002, 10:54 AM
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I think you would be better off finding a rear-ended 560SEL with a good engine and swapping engines, trans, mounts, brackets....
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Old 12-10-2002, 11:23 AM
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Paul offers a very practical suggestion.

Best of luck,
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Old 12-10-2002, 11:29 AM
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I saw a Corvette engine in a 300e once, and it was painted fire engine red.

And there was somebody here who put a Ford 302 in a 190e.
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Old 12-10-2002, 01:10 PM
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Check out these links:

Not W126 models, but it shows what can be done...
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car
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Old 12-10-2002, 01:43 PM
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Location: Battle Ground, WA
Posts: 576
Engine swap...

Hi rmakela,
I have a 1982 300D that I installed a Chevvy 4.3 liter V6 and it's T700R 3 speed auto with overdrive and locking torque converter in, and I LOVE IT! The Chev engine is VERY reliable, MUCH better than a Mercedes - most of the V6's go well over 200K with no problems, and they are VERY smooth running, powerful engines that deliver GREAT fuel economy. I get around 28 mpg on the freeway, at speeds of 75 - 85mph, and around 20mpg around town driving. With the overdrive and locking torque converter, the engine rpms are only around 1650 at 60 mph, 2900 or so at 100 mph. The car ALWAYS starts immediately and runs very smoothly. Since installing the GM engine/trans almost two years ago, I haven't had to do ANYTHING to the drive train. The engine is over 100 lbs lighter than the diesel, so the front of the car sits higher than it used to, but your car's engine probably weighs closer to the V6's weight.
I had the conversion posted on my web site until very recently (changed ISP's), but if you are interested, I could email you some pix, etc...
Keep in mind that the 4.3L V6 makes more power than the small block chevy did when it first came out (up to 200 hp in the vortec versions!), and is shorter, so easier to install than a V8. It has the same bell housing pattern as the 350 engine, which it is based on. The TBI engines are very easy to swap because the electronics is not too complicated, but the later vortec engines make a bit more power.
If you have a good place to work and a good set of tools, you could make the swap... it took me about a month of evenings and weekends. The biggest problem was widening the tunnel to accomodate the T700R4 Transmission. I made the engine pan shorter to clear the front crossmember, but the pan from a 4wd Blazer looks just like what I made, and would work ok, I think. I did have to make up a header for the drivers side exhaust, but that wasn't too difficult. Be sure to use the GM cruise control, as the Mercedes cruise is fraught with design problems and fails early, whilst the GM works forever.
The T700R4 transmission is smooth as silk, and doesn't have any strange problems like the mercedes transmissions do. The engine is smooth-running, and the car drives very well.
Just my opinion! BUT, everyone that's ridden in it likes it too....

Richard Wooldridge
'82 300D/4.3L V6
'94 Taurus
'77 Jag XJ6
'89 Astrovan
'85 GMC S15
'77 280Z
'65 Clark Cortez
'85 Kubota DIESEL tractor - see, I DO like diesels, in their place!
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Old 12-10-2002, 03:30 PM
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I remember very well, the write up, pictures and dialog covering Richard's engine swap project.

From following all that, it was extremely obvious to the casual observer that Richard is experienced in many areas. He is a good welder, a good fabricator and a very savvy guy who is project oriented.

If you fall in this very specialized category, then doing such an engine swap could be a very satisfying project. If you do not, it will be an incredibly expensive proposition to have done. First of all, how do you find someone who you know can do this job properly, to your satisfaction and for reasonable money.

Unless you live near Richard and can manage to contract for him to do it, or you share his vast skill set, I would recommend that you think long and hard before entering into such a project.

Good luck,
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Old 12-17-2002, 06:34 PM
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The Chev engine is VERY reliable, MUCH better than a Mercedes; the Mercedes cruise is fraught with design problems and fails early, whilst the GM works forever; The T700R4 transmission is smooth as silk, and doesn't have any strange problems like the mercedes transmissions do.
Geez Richard. You gush over GM and knock MB so much, it makes me wonder why you went through all the trouble of making the conversion when you could have just gone out and bought a Chevy!
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Old 12-17-2002, 07:04 PM
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Wow, Richard's post even made the hair on MY neck stand up!! What a slander of the world's finest automobile!!!
I just can't understand why anyone would or could do that!! Blasphemous, that's what it is, blasphemous!! You should be ashamed to even claim membership on this board!!
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Old 12-17-2002, 07:36 PM
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Location: Kite, Georgia USA
Posts: 48

I might be trying it myself, if I can't get my 88' 300 SEL running right(mysterious electrical problem). I was thinking about using the 3.8L roller cam engine or a 4.3L engine. One thing that has held me back is not knowing about the gear ratio in the rear end. I'm thinking that it would need a higher gearing to work with any of the GM engines/trans.
You just bypass and eliminate all the mercedes problem electronics.

Go for it


Last edited by BMJR; 12-17-2002 at 07:47 PM.
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Old 12-18-2002, 05:18 PM
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Why bother with converting a MB into a car with NO resale value
If you like chevy so much sell your benz and buy one.
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Old 12-18-2002, 06:37 PM
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Location: Battle Ground, WA
Posts: 576
Chevy Swap...

Hi all,
First, to justify the reason - my brother gave me a 1982 Mercedes 300d for doing some work for him. It wouldn't start, had excessive blow-by, and the price of a rebuilt or exchange engine was far higher than the value of the car. I had the 4.3L V6 sitting in my shop, having purchased it almost a year before for the princely sum of $125, complete with ECM and engine wiring harness. I am retired, and have more time than money. So, I made the swap, and am glad to have done so, as I now have the best of both worlds, in my opinion - a completely troublefree drive train, and a very well built, sturdy body with no rattles. The gearing on my car worked out to be exactly right, no adjustment needed for the speedo at all. The engine rpms are just right for the car's weight, also. The "engine management system", or ECM swaps with the engine, so there is no problem there. The Mercedes already had a GM AC compressor on it from the factory, so the lines were fine for the new compressor. As far as the rest of the electricals, there is no problem there either, as long as you have a degree in electronics, as I do. As Larry Bible mentioned in an earlier post, to do this sort of work, you really need to also have had a course in welding, and have a mig welder or tig welder, as well as a good shop. You must also have an in-depth knowledge of most all the systems in the vehicle/engine you are working on. If you don't see the benefits in this kind of swap, then it definetly isn't for you! If however you are a bit more broadminded and willing to consider the positives as well as the negatives, then go for it! Needless to say, this is not the first engine swap I have performed... I and my brother have done some very interesting things through the years. By the way, what I did was keep a MB from going to the scrap yard, where it otherwise would have gone. Also, the whole swap, including engine, transmission & everything else was well under 1K, closer to $900. That's why a Chevy engine is the way to go...

Richard Wooldridge
'82 300D/4.3L V6
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