Drilling spark plug cooling holes SBC

[BOOT]

Does anyone know if there is water for most aftermarket cylinder heads, specifically sportsman II's? Or if they need to be drilled at an angle or anything weird? I'd like to know more about this mod if anyone has the info, thx. If I had a smaller mirror I might be able to see and tried to feel it out with some wire but seems maybe like there is no void.

Let's skip any why bother or you don't need them time waste.


edit: to be clear the ones on the gasket face and not for coolant lines.

[Walter R. Malik]

Mimic the stock production head hole angles and just drill the holes on the exhaust valve side.

In an endurance type situation it can alter the clamp loading on the head gasket because of localized surface temperatures.
It also helps greatly when a cast iron exhaust manifold needs to be used.

Any other situations seem to be a waste of time.