Personally I would buy a top quality tap. if you bust the tap off in the
manifold the cost of extraction will far exceed the cost of a quality tap.
Also according to this page
http://www.fairburyfastener.com/tap_drill_decimal_inch.htm the correct tap
drill for a 5/16-24 is an I which is .272" in diameter. somewhat bigger
than a 1/4" drill.
Have you considered converting to bolts instead of studs? I find them a lot
easier to work with. YMMV of course.
Good luck,
Rick
On 8/19/07, Councill, David <dcouncill@msubillings.edu> wrote:
>
> Last week I removed my exhaust system. But in the process, one of the
> studs on the exhaust manifold flange snapped. I first made a cut in the
> remnant bolt so I could use a screw drive to remove it. Failing that, I
> tried in EZ-out. But the bolt is securely frozen in place. Yes, I also
> sprayed it over several days with penetrant, two kinds. Finally, I bored
> a hole through the center of the bolt, from the initial EZ-out hole.
> Gradually, in increased the hole up to 1/4". Now I am tapping the hole
> again. But my carbon steel 5/16-18 tap is not making much headway. I
> gave up for a few days and plan to resume the ordeal this afternoon.
>
> Any suggestions? Maybe my Harbor Freight tap is not good enough? Any
> suggestions on a cutting oil perhaps? I should mention that I am doing
> this under the car. I was going to pull the exhaust manifold but being a
> bit lazy and realizing that I couldn't find a better place to hold the
> manifold, it seemed like it was best to do it in place.
>
> I have a few more studs coming from Moss in a few days to complete the
> job. Strange that the previous bolt appears to have molded itself in
> place because it has only been maybe two years. But what is, is and
> getting the bolt tapped is the main task at hand.
>
> Hopefully some of you can reply before I resume the task in about 4
> hours.
>
>
> David Councill
> 67 BGT
> 72 B
> _______________________________________________
> richard.ewald@gmail.com
>
> Edit your replies
>
> Mgs@autox.team.net
> http://autox.team.net/mailman/listinfo/mgs
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