Hi All,

The vacuum advance does work- changes the timing about 12 degrees at idle. I have not checked the timing at 3000 RPM.

I did move the distributor a tooth. but found that I could not bring the timing right in that position. With the distributor body rotated clockwise as far as it would go, the timing now read 12 degrees BTDC with vacuum on. So each tooth moved it like 20 degrees - so an 18 tooth gear?? Sounds about right.

Anyway, I moved it back a tooth, and was back where I started. I think that Joe is right that the position is not likely to be due to chain stretch or tensioner. Probably designed like that.

As I read it - the chain goes in a V pattern, with the crankshaft & harmonic balancer at the bottom of the V, the distributor gear midway up the V on the right side, and the cams at the top of the V. Since, the slack is taken out from the left side of the V (passenger side) - then chain stretch would have the greatest offset on the passenger side cam, about half of that offset on the drivers side cam, and 1/4 of the offset on the distributor. I've read that 12 degree stretch (measured on the passenger side cam) is not acceptable, and at the distributor - this would only be a few degrees.

I just wonder why those brilliant German engineers would design the distributor rotation to be at the end of it's adjustment.

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1983 500 SL (Gone )
1972 350 SL 4.5