What Size Head Bolt Tap

JLWelding · Nov 26, 2010

Need to clean threads in block and cant find size. Also I think its called a bottom hole tap?

06 DIESEL · Nov 26, 2010

You need a bottom tap, or if the head is still on you need a "pulley" tap. A pulley tap is 6" long, a regular tap is 3" long and will not clear the head unless you make an extension for it and pray that it does not fall off in the hole.

See below for a thread dealing with this already.

Bunch of questions on installing head studs (with head still on) - Competition Diesel.Com - Bringing The BEST Together

JLWelding · Nov 26, 2010

Got it ordered, thanks

morkable · Nov 26, 2010

m12x1.5 I use a regular tap, and just a socket and extension to bottom tap

JLWelding · Nov 26, 2010

They said 12mm x 1.75 Which is right?

06 DIESEL · Nov 26, 2010

M12X1.75 is correct.

morkable · Nov 27, 2010

my bad, yes that is right... stupid flu, cant think right... sorry