What size tap do I get for these bolt holes?

[Aaronbrook37]

So, it's a case of the good, the bad, and the ugly.

The good:


The bad:


The ugly:


To solve the bad and ugly bolt holes, I'm going to need to pick up a few things tomorrow before the valve cover with a new gasket can go back on obviously. One of them is going to be a tap so that I can have proper coarse thread M6x45mm bolts going through. Currently, the good and the bad both thread bolts with no problem even though the bad is slightly damaged as you can tell when I was removing the old remains. I should re-thread it anyway. The ugly needs some sort of extractor kit to remove what's left of the old bolt stud from my head and then to be re-tapped accordingly. Then I'll be 11/11 instead of 9/11 holes and oil leak-free!

So the question is this: what exactly is the name of the first and second tool specification I need to pick up at the hardware store tomorrow? I know the first is a tap, but not the correct name in order to properly thread the bolts into the head. Again, they're M6x45mm and I think the thread pitch is 1.0mm. The second is an easy-out or a bolt-out or a screw extractor or something. Thanks all!

[Aaronbrook37]

http://www.fastenal.com/web/products/detail.ex?sku=0326833

Looks like I found what I'm looking for in regards to the tap. Now just to get that old bolt bit out of there!

[Aaronbrook37]

http://www.fastenal.com/web/products/detail.ex?sku=7007278

Looks like this'll probably get the old bolt bit out for me.

[crazyrog17]

Your search was fruitful I see, thanks for posting the links here. Be sure you get a reverse threaded drill bit before you start with those extractors. You have to have a hole to start that extractor in, otherwise it wouldn't even catch with turns from a ratchet.

Also, to drill and tap, drill with the corresponding starting bit size to start. Then turn the tap firmly in 2 half turns and 1 half turn out. Repeat for the whole depth of the bore.

[Festy46]

If you think your threads may be damaged too bad to hold, you can get a Heli-coil kit and install that and keep the same bolt size rather than drilling out to a bigger bolt size. A Heli-coil kit usually comes with a special tap, inserts, and an insert tool. You will usually have to buy a drill bit separately. The kit will tell you what size drill you need.

[Aaronbrook37]

All solved with screw extractors, the M6x1.00 tap, and some careful drilling. Thanks for the help, folks!