380 timing chain

[heckflosse]

I'm thinking of buying a 1980 380SL (107) with 90,000 miles.
I've heard about weak single timing chains and was wondering how big an issue these are;
Do they just snap with no warning or do they tend to rattle first?
What mileage should I consider changing it?
Is it worth while upgrading to a duplex and what costs are involved?

 

[Ian B Walker]

I doubt if you can upgrade to a duplex chain as the crankshaft pulley sits back too far. Machining it down to fit would only make it miss the woodruff key that holds it in position. Or so I have been told.