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Old 07-02-2006, 10:22 PM   #12
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Join Date: May 2006

Originally Posted by Boris740
Can you explain "knock the gap closed"
On some race engines dome pistons are used to raise the compression, these domes are so close to the spark plug that reliefs are cut in the dome. The plugs are then indexed to prevent the piston from hitting the ground electrode.

The concave relief at the bottom of the piston is for the plug.

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