Detonation in my 59AB engine

[Desoto291Hemi]

I’m with the others,,,try the timing .
If it didn’t rattle before,,,,why would it start after boring it an extra.030 ?
And the extra bore shouldn’t really affect the cylinder head clearance that much .
10.9 CR sounds kind of high to me,,,,,check your dimensions and calculations.
Pete and old Ron,,,,and the others know a ton more than I do,,,listen to them .

Tommy