what size hole should be drilled in the manifold? what size tap should be used? thank guys.

 

Depends on your gauge......and what thermocouple....I think my autometer was 1/4" NPT.....

 

Most of the thermocouples are 1/8" NPT

 

they are glowshift. they are going on a friends truck and the instructions dont say.

 

I know times are tough but I would be investing in some good gauges.....I just looked and my Autometer is 1/8"

http://www.autometer.com/productPDF/1129A.pdf

 

i have glowshift in my truck n i've never had any problems with them. i believe my thermocouple was 1/8" npt. you can search the internet and find the size hole you need to drill for each tap, n some tap n dye sets have it right on the case

 

my glow shift stuff came with instructions.

its a 1/8 npt tap. i used a 21/64 bit as the final size.