w108,107 Parts Hoarder
Date registered: Jun 2010
Vehicle: 4Keep:450slc5.0cab 280sl5sp 280se4.5 500seAMG 2sell:500sl92 380se83 300se86 350sl4sp 75slc MorInSig
Location: Philadelphia Area
Mentioned: 34 Post(s)
Quoted: 1801 Post(s)
Usually it's not too hard to figure out why a cinder isn't firing. It sounds like it's a spark issue. Cap, rotor, plug wires, spark plug. I guess it could be distributor wobble, but that would be rare.
You've got a d-jetronic and the 107 (SL roadster) forum has a lot of knowledgeable guys there that can help with a d-jet. Fuel, air, and spark are what you need. If it's not spark (mentioned above) it could be fuel, and if it's only one cylinder , it's probably a simple fix since the ECU and trigger points would both affect more than one cylinder.
Most likely you are looking at an easy fix there.
The deal on the 560sl sounds like a good one, and if you've got the space, it might not be a bad thing just to snag, but virtually none of the parts are common between the two vehicles. I don't know if the exhaust manifolds for the 116 and 107 are the same, but I've got two pairs of 72-73 r/c107 manifolds I'm looking to sell, and I'm certainly not the only guy parting out 107s.
If I were you, I'd probably go the easy route and fix the existing engine. The 560 engine is a whole different and more complicated animal in my opinion.