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Thread: Best exhaust stud drill plate tool? Jims vs. CFU?

  1. #1
    Member AC_Schnitzel's Avatar
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    Best exhaust stud drill plate tool? Jims vs. CFU?

    Worst nightmare confirmed today when trying to replace header... Found broken exhaust stud so now I'm looking for the jig to use.

    Can you comment on Jims 1705 vs. something like this: https://www.amazon.com/Harley-Exhaus...omotive&sr=1-2

    Will it work? Should I have concerns?

    Let me know what you think.

    These instructions say to use a 5/16x18 tap to clean out the threads: http://www.jimsusa.com/pdf/instructi...ts/1705-IS.pdf

    Any tips for how to do this? Do I need a tap wrench?
    Last edited by AC_Schnitzel; 08-25-2019 at 12:23 AM.

  2. #2
    Senior Member GregoXB's Avatar
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    Depending on how seized in the stud is, a tap guide tool might not be able to handle the job. I had to remove my head and gave it to a machinist. Took him two hours using a jig. When he finished he caked the new stud with high temp anti seize and told me never to come back. I hope it goes easier for you.

  3. #3
    Senior Member mmcn49's Avatar
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    Yes the jigs will work but IMO you shouldn't start with a 5/16" drill bit. Suggestions:
    -Spray the stud with PT Blaster or other good penetrate.
    -Go to Harbor Freight and purchase a set of Left Hand drill bits and a set of transfer punches, (they're cheap).
    -Purchase a "High Quality" regular 1/8" twist drill bit.
    -Mount the jig then center punch the broken stud
    -Keeping the 1/8" bit as straight as possible drill a pilot hole, (you won't be able to use the jig for this).
    NOTE: !/8" bits are fairly strong. They won't brake unless you do something dumb.
    -Get the next size up left hand bit and continue drilling.
    NOTE: Keep spraying PB Blaster while drilling.
    -Keep going up one bit at a time.
    -When you have a fair amount of material drilled out, heat things up with a propane torch, a little heat always helps.
    -If your lucky the left hand bit will grab whats left of the stud and twist it out.
    -In spite of your best efforts the drill hole will not be centered.
    -As you near the aluminum threads stop drilling.
    -At this point I would grab a small cape or flat chisel and tap counter clock wise on what's left of the stud to work it out.
    -This is not difficult but takes patience and usually does no damage to the female threads.

    -You can also choose the to set up the jig and drill out whats left with the 5/16" bit.
    -If your lucky you'll drill out most of the stud without damaging the aluminum threads.
    -That said you'll still have to clean out whats left of the steel stud from the aluminum threads
    -Worst case you get to put in a helicoil.

  4. #4
    Member AC_Schnitzel's Avatar
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    Quote Originally Posted by mmcn49 View Post
    Yes the jigs will work but IMO you shouldn't start with a 5/16" drill bit. Suggestions:
    -Spray the stud with PT Blaster or other good penetrate.
    -Go to Harbor Freight and purchase a set of Left Hand drill bits and a set of transfer punches, (they're cheap).
    -Purchase a "High Quality" regular 1/8" twist drill bit.
    -Mount the jig then center punch the broken stud
    -Keeping the 1/8" bit as straight as possible drill a pilot hole, (you won't be able to use the jig for this).
    NOTE: !/8" bits are fairly strong. They won't brake unless you do something dumb.
    -Get the next size up left hand bit and continue drilling.
    NOTE: Keep spraying PB Blaster while drilling.
    -Keep going up one bit at a time.
    -When you have a fair amount of material drilled out, heat things up with a propane torch, a little heat always helps.
    -If your lucky the left hand bit will grab whats left of the stud and twist it out.
    -In spite of your best efforts the drill hole will not be centered.
    -As you near the aluminum threads stop drilling.
    -At this point I would grab a small cape or flat chisel and tap counter clock wise on what's left of the stud to work it out.
    -This is not difficult but takes patience and usually does no damage to the female threads.

    -You can also choose the to set up the jig and drill out whats left with the 5/16" bit.
    -If your lucky you'll drill out most of the stud without damaging the aluminum threads.
    -That said you'll still have to clean out whats left of the steel stud from the aluminum threads
    -Worst case you get to put in a helicoil.
    Thanks for the tips. I bought a JIMS tool equivalent jig that comes with a 1/8 bit and a 5/16 bit. It comes with guides for both.

    Iíll start w/ a left hand bit to see if I can back it out that way before drilling.

    Thank you!

  5. #5
    Senior Member konarider94's Avatar
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    Its just a 1/4" drill, not a 5/16". No need to pilot drill it. I have the Jims tool. It worked so well keeping the drill centered on the stud/hole I was able to pull out the remaining threads of the bolt like it was a helicoil insert. I was able to reuse the existing threads in the head after cleaning it out.

    I see the amazon tool has 2 guides so your pilot bit stays centered. Good idea but a smaller drill bit is more likely to walk on its own. Once you have an off center pilot hole the jig wont work as well. That CFU jig looks like a piece of garbage compared to the jims tool. With a regular steel insert the drill can still cut through it and walk.

    The jims tool uses a hardened drill guide that is not going to let the 1/4" drill walk at all. I would not use a pilot with this tool as you have no way to center it, thats the whole purpose of the jig. The jims tool is $100-$110 on ebay right now. Well worth it in my opinion.

    I wouldnt even bother with a left hand drill bit. If its seized enough to break the stud you better hope that smaller drill bit doesnt catch hard enough to come close to being able to break it loose. Because it wont and you'll break the drill bit the same as a RH twist would. LH drills have their place but broken studs seized in metal is not one of them. Take whatever advice you want but I used to work as a machinist and I have a mill in my garage.

  6. #6
    Member AC_Schnitzel's Avatar
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    Quote Originally Posted by konarider94 View Post
    Its just a 1/4" drill, not a 5/16". No need to pilot drill it. I have the Jims tool. It worked so well keeping the drill centered on the stud/hole I was able to pull out the remaining threads of the bolt like it was a helicoil insert. I was able to reuse the existing threads in the head after cleaning it out.

    I see the amazon tool has 2 guides so your pilot bit stays centered. Good idea but a smaller drill bit is more likely to walk on its own. Once you have an off center pilot hole the jig wont work as well. That CFU jig looks like a piece of garbage compared to the jims tool. With a regular steel insert the drill can still cut through it and walk.

    The jims tool uses a hardened drill guide that is not going to let the 1/4" drill walk at all. I would not use a pilot with this tool as you have no way to center it, thats the whole purpose of the jig. The jims tool is $100-$110 on ebay right now. Well worth it in my opinion.

    I wouldnt even bother with a left hand drill bit. If its seized enough to break the stud you better hope that smaller drill bit doesnt catch hard enough to come close to being able to break it loose. Because it wont and you'll break the drill bit the same as a RH twist would. LH drills have their place but broken studs seized in metal is not one of them. Take whatever advice you want but I used to work as a machinist and I have a mill in my garage.
    OK -- maybe i'll go w/ the Jims afterall.

    Some questions:
    - do I need cutting fluid/paste or penetrating oil?
    - how do I know when to stop drilling w/ the Jims?
    - how to you remove the remaining threads of the bolt?
    - what did you use to clean out? compressed air? 5/16-18 tap?

  7. #7
    Member Endopotential's Avatar
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    I just went through the same headache myself. It was on the front exhaust, but rear stud which made for really tight quarters.

    Anyone know what's on the backside or vicinity of the exhaust stud, if one should drill too deep or at an angle? Looks like there's a tunnel for the valve pushrod? It's still pretty far away from the combustion chamber or exhaust port, right?

    AC - I went through all the above suggestions, and it still took me a full week of careful drilling. Unfortunately none of the heating, left hand bits, extractors etc worked.

    I'm in Pacifica, in case you're nearby. Things I learned:
    - I have a ton of Harbor Freight gear, and for the most part it's worked well and saved me a lot of money. But this is not where you want to skimp. The HF drill bits are not up to the task of drilling out heat hardened metal, and just dull out or snap.
    - It's totally worth it to splurge $5 and get some decent cobalt drill bits. I got some Milwaukee Shockwave bits, and they cut through so much better
    - Don't drill bigger than 9/32". That will still leave enough metal intact for you to run a tap through. If you drill the full 5/16" there won't be anything for your new stud to hang on to.

    Good luck!

  8. #8
    Senior Member konarider94's Avatar
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    Quote Originally Posted by AC_Schnitzel View Post
    OK -- maybe i'll go w/ the Jims afterall.
    Some questions:
    - do I need cutting fluid/paste or penetrating oil?
    Anything to reduce friction will help, motor oil, penetrating oil. Don't need to buy anything special but dry is not preferred when cutting steel.

    - how do I know when to stop drilling w/ the Jims?
    You should be able to tell by the metal chips and the feel. It will drill super easy after you get through the steel bolt so dont go crazy. When drilling by hand i put tape on the drill to know when to stop. I dont remember the exact hole depth but if you have a new stud to put in you'll know how deep the hole needs to be. Put tape on the drill bit where it lines up with the jig with the appropriate amount sticking out the back.

    - how to you remove the remaining threads of the bolt?
    You may see an edge starting to peel out. Grab it with needle nose pliers and or a pick. If not start to run in a 5/16-18 tap. If it starts to bind up remove it and check if the remaining threads are stating to come out and you can grab on to them at that point. I generally like starting with a spiral point tap. Its very tricky to start a hole with a bottoming tap but if you need threads to the bottom of a blind hole eventually you need to switch.

    - what did you use to clean out? compressed air? 5/16-18 tap?
    The 5/16-18 tap would be the way to go there.

  9. #9
    Senior Member GregoXB's Avatar
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    Another thing that can happen, and happened to me, is the other exhuast stud will snap off like a pretzel when you go to fasten down the Jim's tool. Then you have only one out, removing the head and taking it to a machinist. Before spending a ton of $ on the tools and equipment for drilling the stud yourself, make sure that the intact stud is not corroded/seized/compromised and can handle the job of serving as an anchor point for the Jim's tool. Usually when one of the studs is in bad shape, the sister stud will be compromised as well.

  10. #10
    Member AC_Schnitzel's Avatar
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    Quote Originally Posted by Endopotential View Post
    I just went through the same headache myself. It was on the front exhaust, but rear stud which made for really tight quarters.

    Anyone know what's on the backside or vicinity of the exhaust stud, if one should drill too deep or at an angle? Looks like there's a tunnel for the valve pushrod? It's still pretty far away from the combustion chamber or exhaust port, right?
    ...
    I'm in Pacifica, in case you're nearby. Things I learned:
    - I have a ton of Harbor Freight gear, and for the most part it's worked well and saved me a lot of money. But this is not where you want to skimp. The HF drill bits are not up to the task of drilling out heat hardened metal, and just dull out or snap.
    - It's totally worth it to splurge $5 and get some decent cobalt drill bits. I got some Milwaukee Shockwave bits, and they cut through so much better
    - Don't drill bigger than 9/32". That will still leave enough metal intact for you to run a tap through. If you drill the full 5/16" there won't be anything for your new stud to hang on to.

    Good luck!
    I'm in the South Bay -- Campbell.

    Did you not do this with a drill jig, IE Jims tool? Those come w/ a supplied Drill bit.

    Quote Originally Posted by GregoXB View Post
    Another thing that can happen, and happened to me, is the other exhuast stud will snap off like a pretzel when you go to fasten down the Jim's tool. Then you have only one out, removing the head and taking it to a machinist
    anxiety skyrocketing haha

    Kona, thanks for your tips. I have a few 5/16-18 taps (taper, bottoming, and plug).

    Once I've drilled out using the 1/4 bit supplied w/ Jims jig, I run a taper tap? Will I need to back off after a few turns to break off any chips, or anything?

    When you say grab w/ a pair of needlenose -- am I literally just pulling out, or do I need to "unthread" it by twisting?

    edit: sorry for the questions. I've never had to extract a broken bolt, or use a tap


    Last edited by AC_Schnitzel; 08-27-2019 at 10:21 PM.

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