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MG MGF Technical - Lost sparkplug No 2, Why?

Hi all,
Ive just lost spark plug No 2! now both 2 and 3 cylinders have gone. (fired out if the head on the M4 raceway!)
This has rendered my head scrap :-((and i'd just contacted Dave Andrews aswell!)
Does anyone know what causes this?
Is the janspeed manifold making the head to hot?
Why are the threads failing?
the gap had closed on the failed plug, is this a clue?
Any Ideas?
Please help!
J E Reed

Likely causes are that the plug was not sufficiently tightened and it worked lose until it releaed or it was installed cross threaded and released. Viz. poor DIY/cheap maintenance.
Why scrap the head ?? A reasonable mechanic can fit a helicoil wire thread repair without taking the head off. Others cannot do it without removing the head.
Geoff F.
Geoff Farthing

Are you sure you have the correct plugs fitted.

If too long, perhaps the pistons are hitting them.

......just a long shot.
Sam Murray

Alloy cylinder head. Too much torque on replacing the spark plug. Thread fails. Quite a common problem unfortunately. Most people are more used to iron cylinder heads that are much more tolerant of ham-fisted mechanics.
Rob Bell

This thread was discussed between 12/09/2009 and 19/10/2009

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