Thread: Read my plugs please

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Originally Posted by Brigrat

1300 mile, they should by now represent the "burn". On a new motor I would worry about pre-ignition and heat build up with those plugs. If anything you want it a little more rich for break in. JMO, Lon

When it was first broken in, it was set to run rich, but with the tolerances of Mercedes engines (to give you an idea, piston to cylinder wall clearance spec is 0.0005") things were pretty well seated after the first 500 miles. These are aluminum blocks, but they aren't sleeved. As I found out after JE misled me and then told me, oh well, didn't work, if you find someone to make custom sleeves for it will give you a discount on another run of pistons, the way they make it work is by being very careful in piston material selection and extracting the silicon from the block after the cylinders have been machined. So the builder (uh...my new builder, who knows better than to take JE's word on using JE pistons in an MB engine) who did the initial break had then adjusted the mixture to get it pretty close, and left the final mixture tuning to me (for the best as where I live is ~20F cooler than where he is).