• The Forums are now open to new registrations, adverts are also being de-tuned.

Mercedes W114 250 Coupe - help!

Wouldn't the amount of fuel per firing cylinder be the same in theory though? I think it's more likely injector design and opening time - a better injector can fire a smaller amount of fuel with better timing to match the firing cycle which is also synchronised via the ECU rather than mechanically via the distributor.
 
I'm guessing that those other 2 injectors were part filling those long inlet manifold arms with a petrol air mix rather than air meaning that on the induction stroke that the cylinder gets fuel [injector] + a fuel/air [manifold] mix leading to a higher fuelling than dictated by the old injector native capacity. Other thing that seems to be crucial is the injector pulse width which will also effect volume of fuel injected. The whole thing is a minefield !:doh:
 
Don't overcomplicate it!
I'm pretty sure that on non sequential systems the injector firing is split into two events per 720deg CA rotation. Net result is that each cylinder has equal coincidental valve and injector opening. I don't believe it to be so critical as some imagine. A slight loss of initial atomisation (final atomisation is achieved courtesy of heat from the piston crown in any case) is compensated by a much simpler and cheaper system.
To put it in perspective I have a three cylinder engine here that has two carbs and no common manifold. The end cylinders draw from separate carbs, the centre cylinder from both. It's specific output is no different from its six cylinder brother which has three carbs each feeding two cylinders each and equally phased wrt time. Simplicity is the driver.
 
Charles Morgan said:
At present there is a thread on each of the three studs that is used by a retaining nut and washer to hold the injector bracket in place. I envisaged replacing the nut with a hollow tube with a thread of the same size as the nut at one end, and then a stud coming out of the solid part of the fuel rail that seats in the hollow tube. Securing it by thread would not work, but perhaps some sort of clevis pin through the tube and stud to hold it in place - allowing a small degree of movement.

Thoughts welcome.
Click to expand...

How about?....
Scan_20160128_1.png
[/URL][/IMG]
 
Certainly achieves the end result without any faff! Find ally grey coloured ties and it should be relatively inconspicuous.
 
Six stout (I fancy plain black - they wouldn't be out of place but if the preference is for grey...) Ty-wraps in three pairs neatly aligned with the ratchety bits hidden underneath and the tails docked could be quite neat I think. More to the point they will pull the rail down on the injectors but leave it free to expand and be absolutely vibration proof.
Do we have a solution?
If so, when it comes to mount the rail, warm the Ty-wraps prior to fitting and leave the tails to pull down further after the engine has run a few times until they are as tight as they can go then trim.

Can the rail be mounted without welded bosses? Will be a hell of a lot easier if it can.
 
I had Tony over to look at the seats and carpets, which he loves, and managed to explain the fuel rail ideas to him. He liked the tie idea, noticed it could also be tied to the lower part of the manifold which has a bar (also thought of jubilee clips), and thought the bosses sounded a source of complication. The problem is fitting everything to the head at present to check tolerances because the straps holding the engine to the pallet tightly get in the way and I don't want to slacken them off until the engine is on a proper stand to bear the weight. It all looks doable, just tight.
 
Strapping to the manifold was my first thought but the injector retaining brackets just leap out as candidates. Smoothing off with a file the edge where a tywrap will bear the only modification required as I see it. The man to pronounce on it I think is Druk. The engine bay of his R107 says so!
The bosses - I'm struggling to see how they can be accurately enough welded in place, whereas merely drilling holes is a whole lot easier. Space is tight though so I guess further research required. I concur, there is nothing to beat having the hard parts at hand for assessing how things will all fit together. Damn those straps though. Not a disaster though as the task of sorting out the fuel rail is all but planned so once the straps do come off, it shouldn't take long to finish whichever option is preferred.
One more point re tywrapping the rail. The tywraps will break up visually what is otherwise a long shiny surface which was never there originally - disguise a non MB part. This, I think, will preserve a look of originality which has been pursued elsewhere.

Am I the only one who thinks there will be a tear in Tony's eye when he sees the car completed? He's going to love it.
 
Next thing is to work out the sensors, of which the TPS will be the most problematic I suspect - the above links show what has been done.
 
THE PART IN QUESTION APPEARS TO BE TPS BOSCH 0 280 122 001.
From turbo bricks this guy highlights the need for correct orienataion such that the system "sees" the closed and fully open positions.
You can see that the stock throttle shaft is to long, no problems a hacksaw fixed that with much haste! Next, the 850 TPS's closed and WOT points are "clocked" differently than the stock one. This means, its internal stops will not let the throttle close/open all the way if you try to clock it the same way as stock. What I did here was to use a piece of aluminum and started by cutting a square. I first drilled the center to fit over the throttle shaft. Then, I lined it up with the stock bracket (which you can see in the above picture), drilled and screwed it into that. Then, I rotated the TPS to where it needs to be, drilled and screwed it in, then cut away the rest. You end up with something like this:http://www.pbase.com/image/15650818.jpg
You then wire into the 2nd and 3rd terminal, and ground the first. TPS is done!

0280122001 seems to be available on Amazon.
http://www.amazon.co.uk/dp/B000UIOQT8/?tag=amazon0e9db-21

and just for the geeks among us a Russian autopsy!
https://translate.google.co.uk/tran...u=https://www.drive2.ru/l/3762379/&edit-text=
 
It's that sort of thing that frightens me.

I'll have a little look at the TPS on my SM as that is bolt on to an existing D jet system.
 
Slight diversions. The original horns were fubar, so I ordered a retro Bosch set from Germany, listed for the W114. When they arrived I noticed they are considerably larger (and heavier). No dimensions listed in the advert, I really hope they fit as they look splendid and pump out 110dB.
 

Attachments

  • hornydivils.jpg
    hornydivils.jpg
    231.2 KB · Views: 13
Quick appeal to any W114/W115 owners here - could you take some photos of the fuse box area so I can see how it all fits together - I forgot to do this before it was stripped, and consequently I have a box of bits, wires and relays without any guide as to how it all goes back together!
 
Last edited:
You must log in or register to reply here.

Users who are viewing this thread

Total: 1 (members: 0, guests: 1)

Similar threads

philnewmerc
W212, w204, 250 or 350 CDI efficiency?
3 4 5
Replies
90
Views
3K
philnewmerc
philnewmerc
AB24
Towing Stability S212 220/250/350
Replies
6
Views
493
ALFAitalia
ALFAitalia
R
Not Mercedes!
Replies
7
Views
413
Rich764089
R
B
Dipped beam help
Replies
3
Views
282
Trickythemerc
Trickythemerc
MichaelMB
Owning a 123 coupe v 124 coupe v 190 saloon
Replies
16
Views
759
Pontoneer
P
Back
Top Bottom