| adyv8 | -- 05-18-2014 @ 6:53 AM |
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hi have broken 2 studs on my flathead what size tap do I need in thread pitch and threads per inch thanks ady
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| David J | -- 05-18-2014 @ 7:42 AM |
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Not a machinist so I cannot tell you the tech details but the tap used is not normal - it is " tight " . Should be some here that can give you the details on different type taps but that is not me . Again do NOT use any old tap as your studs will be loose and may leak . May wanna elaborate on what year motor you are working on also . 32-34 blocks are very different than 35 and newer blocks in the head stud area .If you have a junk block around try a normal tap in it and you will see what I am talking about . You will be removing material - not just chasing the threads . That is of course assuming someone hasn't already messed it up !!!!
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| supereal | -- 05-18-2014 @ 4:30 PM |
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Broken studs are usual at our shop. The most effective way to extract them is to wire weld a bolt the the reminder. The heat, alone, will usually shake them loose as it attacks the rust. As for chasing the threads, only use a tap for the purpose. A threading tap will destroy the fragile cast iron. If you are not skilled at removal, let a good machine shop do it for you.
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| oldford2 | -- 05-18-2014 @ 5:05 PM |
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I am confused. You say you have 2 broken studs and then you want to know the thread size. So have you removed them yet?? If not, is that part of your question - How to remove broken studs?? Or, Have you removed the broken studs How?? Cleanly?? If so, leave the stud holes alone and put thread sealant on all your studs when you replace the heads. No need to "clean up" the threads unless you buggered them up in the broken stud removal. John
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| adyv8 | -- 05-19-2014 @ 1:41 AM |
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I have managed to remove one stud the other is broken off flush with the block my brother is an machinist and will be able to remove the stud just want to know the tap size to clean the treads before putting new stud In the engine is 1936 v12 zephyr flathead I have an old cyl head to use as a guide to drill out the stud thanks ady
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| David J | -- 05-19-2014 @ 6:20 AM |
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Well that eliminates the 32-34 type worry . Some of the stud holes on them are blind . 35 and up are all open holes . This is on V-8's and doesn't apply here . The tap thing is important still and be sure you get the right one . A normal 7/16 NC tap will screw your hole up . That is the stud will screw in with your fingers and probably leak . The tap thing comes down to " thread class " 2 , 3 , 2B , 3B etc . And again I am not the person to answer that question . You want the tapped hole " tight " so the stud is tight and centered . This message was edited by David J on 5-19-14 @ 6:25 AM
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