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long 11mm 2.0 tap for chasing head bolt threads?

This is a discussion on long 11mm 2.0 tap for chasing head bolt threads? within the General Help forums, part of the LSx Technical Help Section category; I have a 6.0 block that came from a salvage yard. Even after hot tanking it, all head bolt holes ...

  1. #1
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    long 11mm 2.0 tap for chasing head bolt threads?

    I have a 6.0 block that came from a salvage yard. Even after hot tanking it, all head bolt holes are full of gunk and debris.

    I was just going to chase the threads with a tap to clean them out, but it appears the 11mm 2.0 threads are a bastard size. I called the local machine shop supply and they said they would have to have one made and it would take 4 weeks and cost $130.00 for a long shank one that is long enough to reach the threads , or 107.00 for a standard length one.

    Does anyone know of a source to buy one of these taps?

    I need to get the engine together and in the car as soon as possible. I hope to find a tap without having to wait 4 weeks.

    Thank you in advance for any help.

  2. #2
    Moderator Cutlass's Avatar
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    1999 Formula WS6 M6-sold
    2001 Silverado Z71

    What about using brake clean and compressed air? Or maybe an old head bolt? Otherwise Summit Racing sells an ARP LS1 head bolt thread chaser. Its part number ARP-912-0011

  3. #3
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    Navy Blue
    1999 Camaro Z28

    If only because my job requires me knowing way too much about threads, torque, tension and the like....

    The BEST advice I can give anyone is to NEVER put a tap cutter into an existing tap (or chase a threading die over a bolt.) Use a re-threading kit. The taps look more like under sized shank bolts than the traditional tap cutter.

    Putting a new tap cutter in an existing tapped hole causes the threads to get enlarged and the bolt threads differently. Torque/tension numbers change... Things can get ugly... While I understand just about everyone chases threads and taps with cutters (I'm guilty of it too on occasion,) you'll be better off investing in the rethreader.

    Just from a general machine shop knowledge, while that price might be a bit on the high end, it doesn't shock me for fabrication of a specialty one-off cutting tool. Cutters need to be pretty hard, and sharpening them is time-labor intensive on some pricey machinery.

    (Link is to Snap-On for a reference to rethreaders, in NO WAY am I endorsing Snap-On.)

    Edit: Are you positive on M11x2? I can't even find that in DIN standards... there's an M11x1 & M11x1.5

    Re-edit: Should have just looked at Summit!! Must be an automotive DIN... I don't have that info
    Last edited by TokerM; 10-09-2010 at 09:44 AM.

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    Smile

    Thank you so much for the part number for the thread chaser. It is exactly what I was hoping to find. My block had been out in the weather and the bolt holes have a mixture of dirt, sludge and rust, so a ground down old bolt and brake cleaner just was not enough to clean the threads properly.

    Since it is an ARP part number I checked with the warehouse that supplies my engine parts, and they have one in stock. I can have it to my shop by Tuesday.

    Has anyone used one of these 921-0011 ARP thread chasers?
    How long are they?
    In the pictures at Summit they look like standard length taps. How would you drive a short tap in the recessed head bolt holes in a LS block?
    Last edited by wsm9808; 10-09-2010 at 10:48 PM.

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    In case anyone is interested for future reference. I bought the ARP 921-0011 thread chase tool and have included a couple of pictures of it. Hope this helps someone.




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    red
    86 s10 blazer

    there is a seller on ebay that sells a thread cleaner - thread chaser that sells for $24 --- the sellers name is akasandjoe --- all the feedback from the people that have bought one is 100% positive


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