w210 E420 spark plug and gap

[apb]

From the information in other topics, it appears that the Bosch F8DC4 would be the best spark plug.
Any thoughts on what the gap should be? There has been a lot of discussion about increasing the gap setting on other engines.

[mbdoc]

Most EFI engines don't run as lean at idle as CIS engines do, so plug gap at .8mm to .9mm(.036") when new will get the job done. Only other plug would be is BERU UXF-79 ultra-x.

[apb]

Thank you very much!!
Any reason I should feel one way or the other toward Bosch or Beru?

[mbdoc]

Price & availability!!

[apb]

I intend to give the ultra x a try.
Are they already pregapped, or is there something I need to know about checking the gap on these king of plugs? I, of course, know how to gap a regular plug but these seem potentially tricky.

[mbdoc]

All ultra-x plugs are pre-gapped. On my race car I open them up to .055", a total pain but at 7500 rpm______ there is a difference on the dyno!! Since your engine won't go there, just install them!

[apb]

Last question, I think . . .
Now that I have the Ultra X, I am ready to start.
Is there anything I should know about removing the combined individual boot/ignition coil from the plug? I suppose it is a matter of wiggling and twisting - but I want to make sure I don't need to use a special tool to avoid costly damage.