Mercedes W114 250 Coupe - help!

[Charles Morgan]

You should have 'made a tradesman' of it.

I think I get the gist!

Hand a bit better, spent the morning removing the paint and rust from the air filter housing, finding the air inlet sensor location at the same time. Someone had previously painted the thing with rust underneath so getting it back to bare metal is essential. Almost there.

A couple of photos of the distributor after a dust - not bad, some rust to come out but looks trivial.

 

[grober]

Little video of a SUN tester checking out the dwell angle, mechanical and vacuum advance on an old Mercedes Distributor. Doubt there's many of these machines around now. Video is a bit ropey but you get the drift.
[YOUTUBE]JQhTjShoxhQ[/YOUTUBE]

 

[Charles Morgan]

A rather glorious bit of kit. Without it, how might one test the dizzy timings and as importantly adjust them?

 

[Ted]

Dwell angle is a more accurate measurement of contact gap - it takes into account any wear in the distributor mechanism. That's if I remember correctly.
That little earth braid needs to be a good connection - as the contact base plate 'floats' in order to rotate and give the retardation (it is incorrectly called vacuum advance) that wire provides the earth path for the current to pass through the contacts.
A broken wire was the cause of many a misfire as the plate moved round.

 

[Bellow]

A rather glorious bit of kit. Without it, how might one test the dizzy timings and as importantly adjust them?

Mechanical advance is checked with stroboscopic timing light with engine running at appropriate rpm check points. Vacuum advance with hand vacuum pump at appropriate vacuum levels again, with engine running. Scatter is the result of an out of true main shaft best checked with a dial gauge on the bench.
The vacuum advance could be checked on the bench if a method of measuring angular motion of base plate can be implemented. To do the same with the mechanical requires the dizzy be driven (obviously!) with accurate rpm measurement - tricky.
Rougher (bench) checks are to merely confirm that vacuum applied to the capsule causes the base plate to move and that the mechanical advance springs haven't stretched ie, the coils still abut each other - which will require partial stripdown.
There isn't scope for adjustment as such (only the static timing is adjustable and the advance mechanisms are relative to that) merely substitution of any worn or failed parts. (Springs stretch, and the pivot points can wear introducing slop).

Is there anything underneath the felt pad nestled in the centre of the shaft - eg, a bolt or screw head?

 

[Bellow]

Missed the edit time slot....
First checks are that the mechanisms are free. Clamp the drive dog in a vice, hold the body of the dizzy by hand so that it does not rotate either and with the other hand on the rotor arm the rotor arm and shaft should (under light to moderate force) rotate approx 20 degrees clockwise - and spring back on release. The vacuum mechanism can be checked for freedom by pushing the connecting arm toward the capsule.
If both mechanism are free moving (douse if not) and, in the mechanical mechanism there is no unrestrained by spring motion at its starting position, no lateral play on the main shaft (most vulnerable in the direction where a diameter is formed from the contact breaker heel - chances are it is ready to be electronicised.

 

[Bellow]

..

 

[grober]

A rather glorious bit of kit. Without it, how might one test the dizzy timings and as importantly adjust them?

This refers to the slightly older design but the principles remain the same.
Pagoda SL Group Technical Manual :: Electrical / Distributor

The centrifugal advance can be "adjusted" by bending the locating posts slightly altho obviously new springs are the best solution. Altho not obvious from the diagram the two springs are often of different strengths. The lighter one is "stretched" from low rpm and its this characteristic that gives the first [ steeper] part of ignition advance curve The stronger spring may be "loose" at this point and plays no part in the proceedings. At certain rpm point this slack is taken up and further advance begins to be governed by the stronger spring which characterises the second [flatter] part of the advance curve till the advance stop prevents further movement.

 

[grober]

As Ted says measuring the dwell angle [the rotational period while the points are closed of the single points open points+shut cycle of rotation ] is a more accurate way of setting the "effective points gap" . It can also function as a measure of distributor wear as excessive wear is likely to give rise to unusual dwell readings [ with the correct nominal gap set ] and fluctuations of 2-3 degress in readings in a bady worn distributor. [ AS USUAL WITH THESE INTERPRETIVE TYPE RESULTS IT REQUIRES EXPERIENCE OF WHAT A GOOD EXAMPLE OF THE SAME DISTRIBUTOR WOULD YIELD ] Many cheap auto multimeters used to have a dwell angle measurement facility setting built in and could be used to check an old distributor. It would be possible with a little wiring to make up a test rig to test this if necessary out of the car. Typically for measurement of a 4 cylinder engine with 4 lobes on the camshaft the meter would initially be set at 90 degrees and yield a typical reading of say 50 degrees of dwell depending on the points gap. A six cylinder with 6 lobes on the distributer would be set initially at 60 degrees [ 360/6] and yield a dwell angle of 36 degrees --- altho this again varies according to the points gap and distributor lobe profile]
Mercedes-Benz Ponton Ignition Point Gap Adjustment and Vacuum Advance © www.mbzponton.org

 

[WDB124066]

Mercedes-Benz 280 280ce 1973 | Trade Me

 

[Charles Morgan]

Nice car, but my bugbear again - it's MBTex not leather!

 

[Charles Morgan]

Didn't fiddle with the dizzy today but painted up the air filter housing lid and the power steering reservoir lid, both rather nicely I thought until I came back to find blossom stuck on one and a fly on the other. Grrr....

 

[Charles Morgan]

Back from France and Germany, the latter to drop off the rear seats for re-covering at KHM. While driving into Esslingen on Sunday I passed a convoy of Benzes - no W114 but two Fintails, one Pagoda and one W124 convertible. The former were all in flat period colours and looked gorgeous.

Just come back to find some correct 15 inch W115 ambulance wheels on ebay, which will take the 15 inch wheel trims and fill the large arches so much better, so snapped those up!

 

[Charles Morgan]

Went up to see Uncle Simeon to discuss logistics today. The car will be moved up next week, Friday most probably. He'll get the engine and gearbox out then get it off to the windscreen lot to remove the front and rear screen, get out the dash and weld it, then over to Dan and Matt. We reckoned that using the sensors and injectors from the BMW 2.5 litre M20 engine would probably be the most sensible thing for working up the Megasquirt.

There was a lovely little Herald in for some work. Not really visible but the interior was bright red, and it did work quite well. Combine that with a lovely VW splitty being finished by Dan and Matt in that super 60s light green and I'm getting rather keener on the idea of a flat colour. Tempted by

Light Ivory

China blue

Caledonia Green

or even just plain old white

Midnight blue is lovely (works well with red) but really too dark for cool motoring

Ditto Dark olive green

The real shame is I just cannot bring myself to like the colour it is in originally, Papyrus white. It takes some real photographic skill for it even to start to interest me!

 

[grober]

http://www.mbclub.co.uk/forums/2051056-post403.html
Post 403 onwards as a "refresher course".
You know my take on this Charles- Darker Metallics will give more " body" to what is a smaller/narrower car by todays standards whereas lighter flat colours may emphasise this difference in dimensions to modern cars. This may be exactly a more retro- authentic appearance you wish to cultivate of course and is a completely valid path to take.

 

[Deleted member 37751]

Midnight blue is lovely (works well with red) but really too dark for cool motoring

That paintwork looks stunning and such a fine contrast with the red interior.

 

[Charles Morgan]

Keeping that blue looking great is a lot of work - known in the trade as doom blue it can be very flat indeed!

White and red does work really nicely

As does ivory

http://www.carandclassic.co.uk/car/C622694

This blue is also lovely

http://www.carandclassic.co.uk/car/C585732

 

[trapperjohn]

Getting close to the colour of my 124 estate there Charles. Ice Blau it says in the book.

 

[Charles Morgan]

Pearl Blue Ice blue 348 is indeed your colour Mr B

I think the blue of the S class is either 304 Horizont Blau

or 917 Aqua blau

 

[Bellow]

Flat will be more 'period' especially if a currently vogue colour is avoided. Fiat seem to have taken ownership of pale blue....

....and white will fall out of favour at some point (though if it endures as silver did, perhaps not in our lifetime). A flat 'period' colour?

I like. Wouldn't that with the red interior be quite something?

What is the state of play/current thoughts on the dizzy? Is it still part of the MS plan?