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Recreational Mechanic
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Tapping for an NPT tapered drainplug - Help?
Anyone have experience drilling/tapping for an NPT tapered plug? I have a tapered NPT tap, but do I need a tapered drill bit to make the hole? Or just use a regular parallel drill bit on my drill press?
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P Cars: 2022 Macan GTS / One empty garage space ---- Other cars: 2019 Golf R 6MT / 2021 F-250 Diesel / 2024 Toyota GR86 6MT ---- Gone: 1997 Spec Boxster Race Car, 2020 GT4, 2004 GT3, 2003 Carrera, 1982 911SC, 2005 Lotus Elise and lots of other non-Porsches PCA National DE Instructor #202106053 / PCA Club Racing / WRL Endurance Racing |
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04-13-2014, 06:08 AM
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Un-Registered User
Join Date: Apr 2007
Location: Upstate New York
Posts: 902
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Straight drill. You can find a chart online for the tap drill size. I just did one yesterday. What size?
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Don 1988 Targa |
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04-13-2014, 06:11 AM
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Recreational Mechanic
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3/4". Just found it. Drill size is 59/64ths. Fortunately I happen to have a bit that size!! Tapping a factory drainplug into my Corvair differential case. They quit putting in drainplugs after '63.
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P Cars: 2022 Macan GTS / One empty garage space ---- Other cars: 2019 Golf R 6MT / 2021 F-250 Diesel / 2024 Toyota GR86 6MT ---- Gone: 1997 Spec Boxster Race Car, 2020 GT4, 2004 GT3, 2003 Carrera, 1982 911SC, 2005 Lotus Elise and lots of other non-Porsches PCA National DE Instructor #202106053 / PCA Club Racing / WRL Endurance Racing |
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04-13-2014, 06:37 AM
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UnRegistered User
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Start square.
Go slow. Try the plug in the hole when you have threads all the way through. You should have about 3 full rotations of the plug by hand before you start to feel some resistance. In other words, you can't make the threaded hole smaller!
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Bill K. "I started out with nothin and I still got most of it left...." 83 911 SC Guards Red (now gone) And I sold a bunch of parts I hadn't installed yet. |
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04-13-2014, 07:25 AM
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Recreational Mechanic
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I also learned that you have to use an NPTF "dryseal" tap. If you use a regular NPT tap then it will leak unless you put pipe sealer on it.
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P Cars: 2022 Macan GTS / One empty garage space ---- Other cars: 2019 Golf R 6MT / 2021 F-250 Diesel / 2024 Toyota GR86 6MT ---- Gone: 1997 Spec Boxster Race Car, 2020 GT4, 2004 GT3, 2003 Carrera, 1982 911SC, 2005 Lotus Elise and lots of other non-Porsches PCA National DE Instructor #202106053 / PCA Club Racing / WRL Endurance Racing |
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04-13-2014, 12:59 PM
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Registered
Join Date: Dec 1969
Location: chula vista ca usa
Posts: 5,706
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When I learned to tap threads in the old days.....1963, I started using Crisco. It absorbs heat, melts and lubes the cutting very well. I have a small can that is about 25 years old and will be around after I am gone probably. Yes, there are a lot of nice, new modern lubes, but.......
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04-13-2014, 02:27 PM
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Registered
Join Date: Jul 2000
Posts: 5,750
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12 rotations of the tap usually gets you to size, a Bill says check. After about 8 turns of the tap it is good to start checking.
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drew1 wife has 924 turbo |
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04-13-2014, 03:35 PM
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911SC 3.0
1983 Porsche SC
