Chev 350 Into 123 Coupe

[NKowi]

First, allow me to apologize in advance to all you MB purists; I am seriously considering swapping my `85 280ce's M110 for a Chevrolet 350/383 crate engine. I've been driving 123 body cars for years and have always kept them bone stock, but have recently felt the pull of my 1970's hot-rodding years. Since the War Department won't go for another car around the house, and since I am loathe to part with this very rare (and very nice) factory five speed 123 coupe, and since I wouldn't mind too much offending both lovers of Euro and American iron, I have arrived at this point. Anyway, I found this forum by way of a Google search on the subject of Chevy/MB engine swaps and found some, seemingly anyway, fairly bright folks with good advice to offer (which need not include "DON'T DO IT", as I've already agonized over that myself for long enough) on the subject. I've seen several fine examples of such a swap in 108/114/123 bodies, so I figure it can be done without killing oneself or one's bank account. One of the examples, somewhere in this forum, mentions using the existing MB automatic transmission with the Chev engine. I'm especially curious about this aspect of the project as I'd love to keep the Bencedes five-speed. I'd appreciate any reasonable (although I might well be the unreasonable one here. based on what I want to do to this fine old car) input you may have to offer. Finally, if any of ya'll really just can't stand the thought of the bastardation of this final-year 123 coupe, make me an offer - cash or muscle car trade. I'm semi-serious here. I can send photos. As brevity has never been my strong suit, thanks to anyone who has read this far.

[alabbasi]

This conversation has been covered a lot. You will more then likely need modify the body to fit the engine and transmission. Then you have the fuel lines to contend with and fuel pump etc. Then you have to get heavy duty springs etc. All said and done you will be spending a lot of money modifying a car that is pretty rare and would probably be worth more as an original.

I understand what you mean by adding another car, but for a fraction of the cost of what you would pay to do this conversion, you could probably get an 80's camaro / Trans-Am that will satisfy your craving.

[engatwork]

I just recently saw a 123 coupe with the Chevy conversion at the Pull A Part. Based on looking this thing over pretty closely the oil pan had been modified to allow clearance and the header at the firewall, drivers side had been cut/modified to allow clearance at the steering box. The OEM shifter was in place so I assume that the linkage had been worked out to allow it to work with the automatic Chevy tranny. Obviously the motor mounts had been modified and unfortunately, I did not look closely at the radiator/cooling system to see what the changes were there. It is doable without a lot of effort it looked like though.

[boneheaddoctor]

Originally Posted by alabbasi

This conversation has been covered a lot. You will more then likely need modify the body to fit the engine and transmission. Then you have the fuel lines to contend with and fuel pump etc. Then you have to get heavy duty springs etc. All said and done you will be spending a lot of money modifying a car that is pretty rare and would probably be worth more as an original.

I understand what you mean by adding another car, but for a fraction of the cost of what you would pay to do this conversion, you could probably get an 80's camaro / Trans-Am that will satisfy your craving.

You would not need heavy duty springs...the small block chevy weighs less than the OM617............

Oilpan?....late 70's chevy Monza 305 or 260 V-8 pan is a front sump configuration...use the pump pickup with that and you will clear the front crossmember....now for headers???????????????????? lot of different ones out there so something is bound to fit.

[BF_JC230]

A Chevy will help you as BOnehEaddOCtor said for the obvious oil pan set up...

the hardest thing to cross will be the giant steering box, and clearing the headers....

Most of us have converted to rack and pinion for this reason...

My project did not cost me very much at all - in fact that was the point, I was 15, wanted the car - it cost 500...and I got the donor American car for free with everything...

I am running an EFI V6, not a V8...but the problems are the same... I think the LITTLE that needs to be modified to the chassis, can be redone if you wanted to go back to stock - at least the way my dad set mine up...the only big CHOP in mine is the lower cross member to clear the oil pan , that was boxed back in from the back...My engine sits on the same mounts, with new perches...

I would -

Go with a return fuel system
get HD springs and make sure the suspension is good
get turbo grade flex disks...(you most likely will need to make a new mid shaft)
other things I can not think of...
MAKE IT SAFE

good luck!
Jake


my only question is if your coupe is running why not find a dead one to compromise and play with....not to justify it - but mine had a broken connecting rod and all the goodness that comes with it, and substantial body rot....

Originally Posted by alabbasi

This conversation has been covered a lot. You will more then likely need modify the body to fit the engine and transmission. Then you have the fuel lines to contend with and fuel pump etc. Then you have to get heavy duty springs etc. All said and done you will be spending a lot of money modifying a car that is pretty rare and would probably be worth more as an original.

I understand what you mean by adding another car, but for a fraction of the cost of what you would pay to do this conversion, you could probably get an 80's camaro / Trans-Am that will satisfy your craving.

I think he's well aware of the obvious things you mention. I gather from your post that you have a general knowledge but not necessarily extensive - e.g., unless you know the SBC weighs more than the engine he's replacing (and it may well not), how can you say he'll need "heavy duty" springs? But, yes, there are a zillion mods needed but it's not impossible...depends for one thing on how successful he is concealing the job's costs from his War Dept. I think it's a good solution: he wants to keep the car, loves his muscle car days (I can relate - I had an L88 Corvette among other toys) and this would be a nice package properly (I emphasize properly) executed.

[riethoven]

Since the War Department won't go for another car around the house

That's good, I never thought of calling my wife that.

[NKowi]

Thanks for your responses. I remain quite curious about the use of a stock MB tranny with the Chev 350. User 68_Mercedes apparently has a `67 250 that uses them together. I tried e-mailing him but have received no response. Does anyone out there have any insight as to how one might couple the five-speed that's already in a 123 coupe to an SBC?

[boneheaddoctor]

Originally Posted by NKowi

Thanks for your responses. I remain quite curious about the use of a stock MB tranny with the Chev 350. User 68_Mercedes apparently has a `67 250 that uses them together. I tried e-mailing him but have received no response. Does anyone out there have any insight as to how one might couple the five-speed that's already in a 123 coupe to an SBC?

what 5-speed was availible in a 123 coupe?

[NKowi]

I'm a bit embarassed to admit that I don't know the answer to your question. I'll have a look this weekend and will post the results.

[boneheaddoctor]

Originally Posted by NKowi

I'm a bit embarassed to admit that I don't know the answer to your question. I'll have a look this weekend and will post the results.

I will think you are going to find the answer is there was none.


And Very, Very few 240D's even got a 5 speed......

[NKowi]

While I might not hold the depth and breadth of your MB knowledge, I am not so bone-headed as to not know when I am upshifting into fifth gear.

I took a brief look under the car this evening - no lift, just a quick floor-jack, so I couldn't see much. I couldn't see any model or serial number identifying markings, but the transmission was manufactured by Getrag (stamped on the driver's side case).

Maybe this was an after-market tranny, installed by a previous owner - not certain how one might tell. Maybe it indeed came from a lesser (read 240D) model. Again, I can't say. However, if it was factory-installed, I understand why you thought the answer was "none"; I've been driving 250's and 280's for years now (72 250, 76 280, 77 280e, 78 280ce and this beauty of an 85), and this is the first five speed I've come across.

I appreciate your response and welcome any further input or insight you might have to offer.

Thanks!
Norm

[boneheaddoctor]

Originally Posted by NKowi

While I might not hold the depth and breadth of your MB knowledge, I am not so bone-headed as to not know when I am upshifting into fifth gear.

I took a brief look under the car this evening - no lift, just a quick floor-jack, so I couldn't see much. I couldn't see any model or serial number identifying markings, but the transmission was manufactured by Getrag (stamped on the driver's side case).

Maybe this was an after-market tranny, installed by a previous owner - not certain how one might tell. Maybe it indeed came from a lesser (read 240D) model. Again, I can't say. However, if it was factory-installed, I understand why you thought the answer was "none"; I've been driving 250's and 280's for years now (72 250, 76 280, 77 280e, 78 280ce and this beauty of an 85), and this is the first five speed I've come across.

I appreciate your response and welcome any further input or insight you might have to offer.

Thanks!
Norm

Well to my understanding the Coupes never had a manual transmission even in Europe.....

a few of the last 240D's to make it to the USA had a 5 speed stick option (4-speed stick was standard as was the 4 speed auto)

A mercedes 5 -speed stick is a rare bird.(123 chassis and earlier) the newer ones (124 chassis and newer) have a left side starter, the older and hard to find ones I speak of have right side starters......I am not sure if getrag made them for mercedes or Mercedes made them in house as I have not seen one close enough. Someone is sure to speak up however.

Don't know what you will do for a clutch...and not sure this trans is up to handling a Small block chevy...

I think Bonehead is right in questioning if the trans will handle (the torque) Chevy power. I think it's much easier to run a Chev trans and worry about adapting the drive train from there than to try to adapt the MB trans to the Chevy clutch, flywheel, etc. Of course the easier plan would be to use a GM automatic - no clutch set up to worry about and so on. Yeah, there's the attraction of a manual box but the effort to have one may exceed its attraction. Only you can answer that.
Finally, I'd google or dogpile "Mercedes engine swaps" or "Chevrolet engines in Mercedes" etc. to see what you might get back.
Generally speaking I don't think this is an overly complicated swap.

[boneheaddoctor]

I Mercedes W123 5 speed with 200K+ miles on it will bring upwards of $1,000

Clutches for that are almost inadiquet for Turbo diesels adn most certainly are not up to Chevy power....I would definately go with a stronger transmission....one that isn't as rare and expensive as the benz one.