Re: thread sealer on pick up tube?
[Re: BSB67]
#2174393
10/14/16 09:40 AM
10/14/16 09:40 AM
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Joined: Oct 2007
Posts: 736 New York
R/T1968R/T
super stock
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super stock
Joined: Oct 2007
Posts: 736
New York
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Its called NPT national pipe thread taper. It is designed to have an interference fit. If it didnt you would bottom out the threads when it was tightened. I have been in engineering for over 35 years. I have seen many motors where there is pipe dope or teflon stuck in the oil pump!! https://en.wikipedia.org/wiki/National_pipe_thread
Last edited by R/T1968R/T; 10/14/16 09:42 AM.
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Re: thread sealer on pick up tube?
[Re: R/T1968R/T]
#2174442
10/14/16 11:54 AM
10/14/16 11:54 AM
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Joined: Jan 2003
Posts: 75,094 A Banana Republic near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,094
A Banana Republic near you.
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I have seen many motors where there is pipe dope or teflon stuck in the oil pump!!
That's because the donkey that put it on there put too much on and went right to the end of the threads.
running up my post count some more .
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Re: thread sealer on pick up tube?
[Re: dogdays]
#2174742
10/14/16 06:41 PM
10/14/16 06:41 PM
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Joined: Jan 2003
Posts: 25,988 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,988
Rio Linda, CA
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NOT All pipe threads are tapered. There is a standard for straight pipe threads, NPS. I believe the oil pickup tube is NPS. Correct, the factory tubes and the MP replacements are straight pipe thread (measure it for yourself) but the block threads are tapered so there is enough interference fit to allow the pipe to tighten without using a jam nut. Since a NPT combo is often known to leak, a straight/tapered combo is likely to leak also so a sealer seems prudent.
The INTERNET, the MISinformation superhighway
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Re: thread sealer on pick up tube?
[Re: John_Kunkel]
#2174777
10/14/16 07:54 PM
10/14/16 07:54 PM
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Joined: Aug 2003
Posts: 43,303 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,303
Bend,OR USA
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NOT All pipe threads are tapered. There is a standard for straight pipe threads, NPS. I believe the oil pickup tube is NPS. Correct, the factory tubes and the MP replacements are straight pipe thread (measure it for yourself) but the block threads are tapered so there is enough interference fit to allow the pipe to tighten without using a jam nut. Since a NPT combo is often known to leak, a straight/tapered combo is likely to leak also so a sealer seems prudent. I learned something new today
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: thread sealer on pick up tube?
[Re: Cab_Burge]
#2174782
10/14/16 08:00 PM
10/14/16 08:00 PM
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Joined: Feb 2005
Posts: 4,320 Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,320
Prospect, PA
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NOT All pipe threads are tapered. There is a standard for straight pipe threads, NPS. I believe the oil pickup tube is NPS. Correct, the factory tubes and the MP replacements are straight pipe thread (measure it for yourself) but the block threads are tapered so there is enough interference fit to allow the pipe to tighten without using a jam nut. Since a NPT combo is often known to leak, a straight/tapered combo is likely to leak also so a sealer seems prudent. I learned something new today I use to get flamed for stating this in past posts. I guess people finally pulled out their calipers.
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Re: thread sealer on pick up tube?
[Re: BSB67]
#2174793
10/14/16 08:16 PM
10/14/16 08:16 PM
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Joined: Oct 2007
Posts: 736 New York
R/T1968R/T
super stock
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super stock
Joined: Oct 2007
Posts: 736
New York
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I think some of you are a little confused, look at the definition of NPT. The taper is actually in the thread angle itself. Its not that the pipe (or hole) gets smaller on the end.The different thread angle is what causes the interference. This would agree with what john said above. This is from the engineering tool box website. the angle between the taper and the center axis of the pipe is 1o 47' 24'' (1.7899o) truncation of roots and crests are flat 60o thread angle pitch is measured in threads per inch
Last edited by R/T1968R/T; 10/14/16 08:20 PM.
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Re: thread sealer on pick up tube?
[Re: mopar dave]
#2175037
10/15/16 02:44 AM
10/15/16 02:44 AM
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Joined: Jan 2003
Posts: 7,498 Minnesota
Hemi_Joel
master
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master
Joined: Jan 2003
Posts: 7,498
Minnesota
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I use red loctite too. Maybe it's not needed, but it has never caused a problem for me.
[img]http://i.imgur.com/boeexFms.jpg[/img]31 Plymouth Coupe, 392 Hemi, T56 magnum RS23J71 RS27J77 RP23J71 RO23J71 WM21J8A I don't regret the things I've done. I only regret the things I didn't do. "Wise men talk because they have something to say; fools because they have to say something. ~ Plato"
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Re: thread sealer on pick up tube?
[Re: R/T1968R/T]
#2175153
10/15/16 11:31 AM
10/15/16 11:31 AM
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Joined: Sep 2003
Posts: 19,624 north of coder
moparx
"Butt Crack Bob"
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"Butt Crack Bob"
Joined: Sep 2003
Posts: 19,624
north of coder
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I think some of you are a little confused, look at the definition of NPT. The taper is actually in the thread angle itself. Its not that the pipe (or hole) gets smaller on the end.The different thread angle is what causes the interference. This would agree with what john said above. This is from the engineering tool box website. the angle between the taper and the center axis of the pipe is 1o 47' 24'' (1.7899o) truncation of roots and crests are flat 60o thread angle pitch is measured in threads per inch the above statement[s] are true. however, for example, a 1/4-18npt thread can be taped using a 7/16" drill for a through hole and get acceptable results. but you will get superior results using a 27/64" drill and a 1/4npt TAPERED reamer, which as the description implies, DOES make a tapered hole. this method is better because it can be used with or without sealer, and assists the 60* thread angle in doing it's job as designed. the practice of using straight through holes was started as a cost saving manufacturing move when it was discovered acceptable [usable] results could be obtained using a non tapered hole for most applications requiring pipe threads. in the above example, the 7/16" drill size is also the required size for a 1/4-18nps[coupling] thread, allowing use of just a common drill without a reamer operation for both types of pipe threads. i also own several common sizes of taper gages used to ensure the proper hole TAPER is obtained before tapping a tapered pipe thread. these gages have a very pronounced [obvious] taper that can be easily seen by the eye. i used this method daily for 42+ years as a machinist tapping 1/8 through 4"npt threads in natural gas metering devices. upon the advent of cnc machining, the tapered reamer was made obsolete in the smaller [1" or less] sizes as it was very easy to bore a tapered hole of the required dimension needed for the larger sizes, and this hole taper was a mandated check for quality purposes.
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Re: thread sealer on pick up tube?
[Re: moparx]
#2175472
10/15/16 09:25 PM
10/15/16 09:25 PM
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Joined: Jan 2004
Posts: 13,247 Mt. Vernon, Ohio
dartman366
I Live Here
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I Live Here
Joined: Jan 2004
Posts: 13,247
Mt. Vernon, Ohio
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I think some of you are a little confused, look at the definition of NPT. The taper is actually in the thread angle itself. Its not that the pipe (or hole) gets smaller on the end.The different thread angle is what causes the interference. This would agree with what john said above. This is from the engineering tool box website. the angle between the taper and the center axis of the pipe is 1o 47' 24'' (1.7899o) truncation of roots and crests are flat 60o thread angle pitch is measured in threads per inch the above statement[s] are true. however, for example, a 1/4-18npt thread can be taped using a 7/16" drill for a through hole and get acceptable results. but you will get superior results using a 27/64" drill and a 1/4npt TAPERED reamer, which as the description implies, DOES make a tapered hole. this method is better because it can be used with or without sealer, and assists the 60* thread angle in doing it's job as designed. the practice of using straight through holes was started as a cost saving manufacturing move when it was discovered acceptable [usable] results could be obtained using a non tapered hole for most applications requiring pipe threads. in the above example, the 7/16" drill size is also the required size for a 1/4-18nps[coupling] thread, allowing use of just a common drill without a reamer operation for both types of pipe threads. i also own several common sizes of taper gages used to ensure the proper hole TAPER is obtained before tapping a tapered pipe thread. these gages have a very pronounced [obvious] taper that can be easily seen by the eye. i used this method daily for 42+ years as a machinist tapping 1/8 through 4"npt threads in natural gas metering devices. upon the advent of cnc machining, the tapered reamer was made obsolete in the smaller [1" or less] sizes as it was very easy to bore a tapered hole of the required dimension needed for the larger sizes, and this hole taper was a mandated check for quality purposes. and if you show one of the younger CNC machinist today a tapered pipe reamer, they look at you and ask what the heck is that for and I tell them back when I was younger doing aerospace machining that was the only acceptable way to thread tapered pipe threads, especially in cast iron and as far as thread sealer,,never seen a plumber yet that didn't use it.
Last edited by dartman366; 10/15/16 09:27 PM.
Light travels faster than the speed of sound,,,this is why some people seem bright untill you hear them speak.
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