Knocking is a dull metallic sound you often heard inside the block, this due to detonation brought about by some factors such as:
1) High compression - Exceed the stock compression ratio to some extent
2) Timing is too advance
3) Low octane fuel
Caltex gold has higher octane rating is it...
You guess it right ha ha, nope actually, I used three bond liquid gasket. But you must check that the mating surfaces dont have pits or uneven surfaces. The torque is the same.