Mercedes W114 250 Coupe - help!

[grober]

Even with a small block chevy those struts have to go.

before

after

 

[Charles Morgan]

I wonder if a custom brace could be fitted over the engine? If MB put one in there must be a reason.

 

[John Jones Jr]

I wonder if a custom brace could be fitted over the engine? If MB put one in there must be a reason.

Wouldn't be concerned about the struts, it's far from the biggest of issues going the V8 route. A redesign of some sort would solve that. In actual fact the current design could be improved upon from a strength aspect.

 

[Druk]

I've found his album - this is helpful too

This is the most revealing pic. Imagine the 114/107 crossmember is just behind the sump approx where the No21 is in the M110 section. Now transfer that position to the 103/104 engines and you can see how these engines simply won't drop straight in without major sump mods. The earlier series engines had sumps with the main pan much further forward to clear the big crossmember.
I had to manufacture a steel sump to get the OM606 into the 107. The 606 is essentially the same crankcase as the 104.
Pics later when I get back on the PC.

 

[Charles Morgan]

A post of much wisdom. I don't understand the current model and its strengths and weaknesses, so festina lente.

 

[John Jones Jr]

, so festina lente.

That's the way to go.

 

[Charles Morgan]

A night of reflection. My budget is reasonably tight for this car as it was an unlooked for arrival, and experience teaches me money spent on mods does not necessarily add to the value of a car, indeed often the reverse.

I have had W124s with the 104 engines, they are fine, but not light on fuel and really if I wanted a coupe with a 3.2 I'd buy a W124, it would be a lot cheaper and a lot easier. The same applies to the M103, it's a step down from the 104 and heavier on the fuel. A wise man told me never to fight a car, and in this case I'd be fighting it to produce a replica W124 at twice the cost. Anyway, I have an Alpina for long fast road trips or an SM for the longer ones.

What I do lack is a long endurance classic that doesn't cost the earth to fuel. Derek's diesel 107 is a stunning thing, the OM606 turbo diesel is an immensely refined engine that could take me to the ends of the earth. It was a huge project though - a lesser man would have packed it in a long time before, and unlike Derek I can't do 90% of the stuff with my skills or equipment. Would I use if for long distance travelling, especially without un-airconditioning and seats that I suspect would do my back in?

So it is a car like most classics to be wheeled out on the odd weekend when I'm not driving the other ones with the occasional medium outing. For that it should be fun. I'm not going to run it as a track car, a BMW 2002 would be a far better thing, nor a dragster. It is a boulevardier, with the red interior (look at this album ) it is almost pimped as it is. A bit of noise, induction (triple Webers with trumpets) or V8 burble?

Re-doing it as per my SM with Megasquirt etc is not going to be cheap and unlike the SM with its extra 34 horses and Maserati soundtrack, this is going to be on the edge of frustrating, as it will have the same power to weight ratio as my 127 but without the chuck ability. It would be more economical, but that really isn't the point, I'd always favour the SM for a long continental trip (LHD, air-conditioning, spectacular ride and comfort, that extra shove and sound).

So, stock, Weber it or V8? James's kind offer of the 420 looks the most sensible V8 for this car - 230 bhp is ample! Getting it to work and fit, plus an auto box and rear diff - probably more work than one thinks. Definitely upgraded braking - as the callipers are going to have to be restored, then that could be done sensibly - plenty of twin calliper W124 brakes around. Triple 40 Webers - £750 for the Webers, all that is then needed is a fabricated manifold and the engine bay can be made to look really lovely. It may not go faster and would eat the fuel a bit more, but it would be fun.

My suspicion with stock is the engine (specifically the D Jet) will need a lot of sorting. That could eat a decent amount of money (probably the money for Weber fitting) and still be marginal at the end.

Fun to play around with the thoughts.

 

[grober]

I wonder if a custom brace could be fitted over the engine? If MB put one in there must be a reason.

Because of the triangulation effect the struts would have markedly improved the rigidity of the front engine cell. That said it might be argued it was typical of the period Mercedes over-engineering and was not strictly necessary. [ I remember early Ford Consol / Zephyr monocoques similar triangulation bracing till the designers got more experience ]

Later models might have achieved the same effect with slightly deeper chassis rails and smaller sheet metal triangulation where the chassis rails meet the bulkhead.
My feeling is that these American "v8 transplant hotrodders" pay scant attention to the final overall body rigidity of their creations and its effect on handling. We tend to take for granted the immense body rigidity modern Mercedes have and how this permits suspension systems to work effectively. I'm not saying its dangerous or anything but as you say Charles it was there for a reason!

 

[Charles Morgan]

My money is always on a bunch of highly skilled and experienced German engineers with a large budget working for the most quality conscious carmaker of the time over a chap with a hound dog called Robert E Lee and a barn full of moonshine, or indeed Fred in his shed in the West Midlands...

My Allard lacks a lot of structural bracing, apart from the wooden superstructure, the engine is insufficiently braced so when you introduce vibrations as a result of riding the clutch (vital for low speed manoeuvres) the entire car shakes viciously.

The thing about modding is that it is fun, but unless it is done with a huge attention to detail it really does ruin a car (my 02 was a case in point - the original modding was shockingly poor and required considerable remediation - self tapping screws through the boot floor millimetres away from the fuel pipes as just one of many examples) but even the good mods require a huge amount of skill to get to look right, and drive right. I was lucky with my Allard that the chap doing all the mechanical work knew the engines and drivetrain inside out and had real machining skills. It still took years and a lot of money to get right. Mind you, that was built originally by a chap called Sid in a shed in Clapham!

 

[grober]

if you are thinking of the Weber route this lot look as if they know their stuff
[YOUTUBE HD]37bB7EPpQu0[/YOUTUBE HD]

As do Burtons

http://www.burtonpower.com/parts-by-brand/brands-u-to-z/weber.html

 

[John Jones Jr]

Triple 40 Webers - £750 for the Webers, all that is then needed is a fabricated manifold and the engine bay can be made to look really lovely. It may not go faster and would eat the fuel a bit more, but it would be fun.

Before you actually go down that route, speak to a pro. I'd imagine a set triple carbs won't be anywhere near utilised without a head job, suitable cam and a decent flowing exhaust manifold. May as well fit a modern retro fit electronic ignition system too. Triple (pun intended ) your £750.

Bear in mind, for less than or similar money you could have an EFI set up, which would be transferable to another engine at a later date.

 

[Charles Morgan]

The Webers wouldn't be sized for performance improvements, if two will do the job of the same level of fuelling as the D jet then that is what will go on. They are simply meant as a replacement for the D Jet so I don't spend a lot of time and money getting that running.

I've done EFi on two cars now, both have delivered a small increment over stock in performance, but all meaningful performance enhancements on the standard engine would require one or more of better in and outflow, higher compression, more aggressive cam and better fuelling. If the 250 was regularly tuned up all parts would be there, but I doubt there is any question about the ideal engine for tuning up that would result in an M114 as the answer. It would be cheaper to stick the V8 in I suspect.

Economics will be done to the last penny!

 

[Bellow]

This is the most revealing pic. Imagine the 114/107 crossmember is just behind the sump approx where the No21 is in the M110 section. Now transfer that position to the 103/104 engines and you can see how these engines simply won't drop straight in without major sump mods. The earlier series engines had sumps with the main pan much further forward to clear the big crossmember.
I had to manufacture a steel sump to get the OM606 into the 107. The 606 is essentially the same crankcase as the 104.
Pics later when I get back on the PC.

If the M104 was still under consideration...I'd modify the crossmember rather than the sump on the basis that the cast alloy sump probably imparts rigidity to the engine block. Not necessarily structurally, but to quell NVH.

Because of the triangulation effect the struts would have markedly improved the rigidity of the front engine cell. That said it might be argued it was typical of the period Mercedes over-engineering and was not strictly necessary.

Could be to stifle a shimmy.

My feeling is that these American "v8 transplant hotrodders" pay scant attention to the final overall body rigidity

Yanks at the layman level are lousy structural engineers. Where we would instinctively triangulate, they bend a pipe around a gate post and are delighted with the result - once they've had it chromed of course.

My money is always on a bunch of highly skilled and experienced German engineers with a large budget working for the most quality conscious carmaker of the time over a chap with a hound dog called Robert E Lee and a barn full of moonshine, or indeed Fred in his shed in the West Midlands...

Hell yeah!

My Allard lacks a lot of structural bracing, apart from the wooden superstructure, the engine is insufficiently braced so when you introduce vibrations as a result of riding the clutch (vital for low speed manoeuvres) the entire car shakes viciously.

At the time of the braced shells in question (MB and Ford) being produced a couple of innovations would have been being introduced that tested the body-in-white engineer's knowledge. Ford struggled initially with wheel wobbles on the first McStrut systems and the move from radials to crossplies must have brought its own headaches.

Before you actually go down that route, speak to a pro. I'd imagine a set triple carbs won't be anywhere near utilised without a head job, suitable cam and a decent flowing exhaust manifold. May as well fit a modern retro fit electronic ignition system too. Triple (pun intended ) your £750.

Well, the head needs to be converted to run on un-leaded anyway....

Bear in mind, for less than or similar money you could have an EFI set up, which would be transferable to another engine at a later date.

Can the OM104 be run away from donor on its own management, and when coupled to an auto box? Is this question unanswerable or haven't I asked it often enough yet?

 

[Charles Morgan]

Well, the head needs to be converted to run on un-leaded anyway....

I keep forgetting this! It's not something I've ever had to do but will no doubt be costly!

A donor engine starts to look better.

To answer your question, I think the M104 will not run under its own juice without an ECU that has been re-programmed. Certainly my 104 engined estate had numerous issues when one of the ABS wheel sensors went. I'm not sure about the M115 that James suggested - it's a much earlier engine design. I suspect in both cases the problem is not insurmountable.

 

[Bellow]

I keep forgetting this! It's not something I've ever had to do but will no doubt be costly!

It is quite a machining heavy task and then there are parts on top of that.

A donor engine starts to look better.

With a donor engine the W114's engine can be laid aside, left entirely original, should it ever be required to revert the car to absolute standard.

To answer your question, I think the M104 will not run under its own juice without an ECU that has been re-programmed. Certainly my 104 engined estate had numerous issues when one of the ABS wheel sensors went. I'm not sure about the M115 that James suggested - it's a much earlier engine design. I suspect in both cases the problem is not insurmountable.

Thank you! At last, someone has answered a question I've been asking on MB-Club for ages. Pity the answer is the one it is though. A modern(ish) unit but requires thorough integration with a vehicle's electrics to work. It is, for this project, the only viable replacement six (unless the M110 is still in contention).
Looks like it's going to be a V8 transplanted then (assuming a transplant is chosen). Yank or German? Manual or auto?

 

[Charles Morgan]

Meanwhile, for the second day running Nice Mr Parcelforce has delivered me a beautifully intact parcel from Turkey with each individual item swaddled (more Christmassy than wrapped) in layers of bubble wrap and no problem clearing customs. Headlights are perfect, H4 bulb compatible (hello high voltage proper lights - relays needed) with just a small need to adjust the connectors to fit.

All these presents every day, it's Wizzard!

 

[Charles Morgan]

I'd prefer it to be German and auto, but if the latter is not possible then the list of European manual boxes is pretty small (Getrag dogleg) whereas the GM boxes are available in spades.

 

[grober]

If you go down the Carb ROUTE these guys might be worth a look?
Weber Conversion Kits - German Cars - Mercedes - JAM Engineering Fuel Systems

 

[John Jones Jr]

Well, the head needs to be converted to run on un-leaded anyway....



Can the OM104 be run away from donor on its own management, and when coupled to an auto box? Is this question unanswerable or haven't I asked it often enough yet?

Changing the head for unleaded and optimising it to take advantage of a triple carb set up are two entirely different things.

Of course an M104 can be fitted using it's own engine management, provided it's done by somebody that has the ability. As for a five speed auto, no idea. I'd be opting for a M103 with standalone EFi plus a four speed auto or a five/six speed manual.

 

[John Jones Jr]

The Webers wouldn't be sized for performance improvements, if two will do the job of the same level of fuelling as the D jet then that is what will go on. They are simply meant as a replacement for the D Jet so I don't spend a lot of time and money getting that running.


Economics will be done to the last penny!

One single twin choke would sound like a better option then...