what size drill bit and tap do i need ?

[RobertP]

i have a isspro egt gauge with a 1/4" probe so the threaded part it about 7/16 that is what the instructions say. but they dont say what size tap to use .

 

[rbattelle]

You need a 1/4" NPT tap.



-Ryan

 

[JKinney]

Although I did my own I dont recall the size, but I believe it is a 1/4" pipe tap,meaning a pipe thread.

 

[4xquadrod]

1/4"-18 Pipe thread uses 7/16 drill.

 

[rbattelle]

Remember to use cutting oil, too...



-Ryan

 

[RobertP]

cool thanks for the fast responses. installed the boost gauge and the wired the egt up so the only thing i have left is to drill and tap first thing in the morning after going to buy the tools. i figure the tap would be in my set, i figured wrong. good thing i decided to check for all tools before drilling.

 

[Cattletrkr]

1/4"-18 Pipe thread uses 7/16 drill.

Whoa there. Just the other day I moved dad's probe from post to pre and I swear the tap said to use a 11/32nds bit. I'll go check. It should be stamped right on the tap.



EDIT: Nevermind. Dad's is autometer and required 1/8"NPT which uses the 11/32nds.