What size tap to clean head bolt threads in block?

[drewbuddy]

My head bolt threads and hole are kinda gunky, and i can't find thread size anywhere, gonna keep searching but..Need to clean them up so wondering if anybody out there knows the size of bolt/tap to clean up the threads. Thanks

 

[Pupdeck]

I can't answer the exact size however I use a factory headbolt and take a cutoff wheel and put 3 or 4 lengthwise cuts against the threads mimicking a tap. It cleans block threads very nice for the headbolts and it's free.

 

[tds]

What he said. You do not want to use a tap to clean up threads. A tap will cut some material out of the threads. You would use what is called a thread chaser, which is essentially what the previous poster described.

 

[kchaazz]

I can't answer the exact size however I use a factory headbolt and take a cutoff wheel and put 3 or 4 lengthwise cuts against the threads mimicking a tap. It cleans block threads very nice for the headbolts and it's free.

^^Yup, this is the way to do it. Ive got several different sized bolts modified this way for cleaning threads at home and it works great for almost everything on the block, especially for removing old rtv from transmission case threads and such. If you were to use a tap for this, youd almost certainly jack the threads up.

 

[drewbuddy]

K thanks

 

[Gstclipse69]

FWIW I believe the head stud thread is m12x1.25

 

[DSMattitude]

FWIW I believe the head stud thread is m12x1.25

X2 ^ And yeah the cutting bolt trick works, though having chasers is pretty nice.