No hole for knock sensor

[NorCalTurbos]

I have a 3.8 turbo block from before sfi and it doesn't have the hole where the knock sensor goes I need to drill one what's the safest way to do this ?what type of bit to use ?I noticed a nipple on the back of the block that looks like the same spot Gn tapped my original sfi block is that the spot?

 

[pacecarta]

its just an 1/8 npt hole
most std bits will drill it. its just cast iron which is pretty easy to drill compared to any other type of steel

drill bit needed is unique for the npt but ive done them with a std drill bit . i grab whatever is in my bit drawer that looks just a shade larger than the end of the 1/8npt tap, drill it through and then walk it around at the top so its tapered or use a step bit and walk it a little then run down the tap with some grease on it

 

[NorCalTurbos]

Hey thanks it's a good time for me to add it while I got the intake off