plugs keep coming loose

[pd100x]

I have 96 shee and it’s got big bore CT racing pistons in it with 19cc domes and billet coolheaded  34 mm carbs  brand new fmf pro circuit pipes  I have 210 psi compression out of each cylinder my spark plugs keep coming loose can someone please help m

[T13]

Your detonating. You need higher octane fuel, less timing or less compression to stop plugs from backing out

[Tedder]

Better get to the root of the detonation problem before you tear her up.

[locogato11283]

“Keep coming loose.”

Probably already caused damage.

[Tedder]

I keep this in my shop to remind me that lean is mean.

This damage was caused from light detonation that was felt right away and throttled out.  

In addition to what you see of this Hot Rod crank bearing a tiny sliver of the race found its way into the combustion chamber and torn up the piston, dome and nikasil.