I am glad that you are reading this as I really have such good news to report. My 1970 280sl with mechanical fuel pump has had all the usual problems, lumpy tick over, stalling at lights fear, erratic take off and even wobbly gear changes. The car has been in and out of the **@$£@!! garage to mechanics who I can only describe as monkeys. I was locked into using them because of warranty obligations which I have sacrificed upon the recommendation of one of the forum users. I went to southern carburettors in Morden, South London..
http://www.sciperformance.co.uk/ and have had a 123ignition system fitted and a full tune up done. They also replaced the coil and the HT leads and the total cost was £501.00.The car was 30 grand, so this is nothing is it? I was told by Roy that the pump may need tweeking but not by him as they only do what they do and I was given a full and easy to undersatnd report on my car. Let me tell you, it has never felt better. All the bubbling and traffic light fear has gone and the car feels totally different. I so wish that I had done this before and not wasted my time listening to all the rubbish that I have had to over the past months. Things like .."its 35 years old, what do you expect?..." they all smell of petrol"..."you need the engine rebuilding"...yeah, well they're all like that"
My only regret is that I won't be able to use these fantastic chaps at sci carbs again as their work here is done. Please consider this modification to your car, go the whole way and your car will behave like you never imagined. I never thought that mine would feel so sweet, and please please use these guys, they are keen and fantastic and I cant reccomend them enough...or had you already guessed that?
paulr