Hi,

I am tuning vette 97, 92 fast manifold & TB, bat heads, magicstick 4 cam, 383 stroked, 36 injectors....etc

It reads 17 deg, whenever I advance it, it knocks. I did many before with the same setup, usually they accept 28 deg. Any idea gents????

The AFR is 12.3 ~ 12.5.