Bottom Tap for Head Studs

N

nate

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Apr 6, 2008
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I have read on here that it's a good idea to bottom tap the holes for headstud installation.

The problem is so far I haven't found a tap that would be long enough and I haven't found a clear solution to this on here either.. My brother is an engineer and machinist, so I asked if he could find something for me. He hasn't found anything long enough either.

So... where do I order this tap?

I was not planning on headstuds, but I have be advised it's a good idea if I'm hitting 40psi or more boost to save the headgasket.
 
I bottom tapped 3 of my holes and then quit. I only got maybe 1-1.5 extra threads out of them and I didn't see the need to risk breaking the tap or screwing something up for 1-1.5 threads. All my studs sit at the same height to so I know they are all at the same depth. I screwed them all the way in and then backed them off 1/2 turn to make sure they aren't bottomed out. Ran in to 2 or 3 other blocks just like this. Almost all holes were bottom tapped already or you only got maybe 1 thread.

Now, with that being said, it's a wise idea to run a tap down there anyways just to help clean out the threads of dirt and debris.
 
Yeah I have gone through MSC and couldn't find anything.

My brother has many sources that aren't so common and they pretty much just deal with machine shops/production shops and came up dry with all of those as well.

I know I could use a normal length tap if I pulled the head, but I'd rather not.

Other thought was to weld an extension. Talked to my brother about it and he didn't think it was a good idea. I guess the metal that taps are made from don't take welding well from his experience.

Honestly I'm not sure. I trust him since he does it everyday and went to school for it and all. I'm just a shadetree mechanic.
 
i took a tap and cut the last few thread off of it so it couldnt recut the threads in the block. The i ran them all the way down and took a small magnet and got the metal out and then blowed the holes out with air. You would be suppriesed how much crap i got out.
 
Yeah a taper tap would work and like you did, just cut the taper off... but it still needs to be long...
 
The type of tap your looking for is called a pulley tap. McMaster has them. Do a google search. :Cheer:
 
Yes, I thought I had that in my first thread, guess not.

My brother did find pulley taps, but they were spiral cut or something like that and he said it wouldn't work at a hand tap. Dunno.

I will talk to him about it again. Been a few weeks since I was able to get him on the phone.

12mm x ??? and length???

I had it written somewhere, but I can't find it.
 
I have one I think it si 12mmx1.75x 6" you can borrow it just return it when you are done and add a few bucks to cover shipping Rob
 
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