Plugging a Hole - SAE, NPT, WTH?
#1353049
12/17/12 03:26 PM
12/17/12 03:26 PM
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Joined: Aug 2008
Posts: 757
Northern VA
bulletpruf
OP
super stock
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OP
super stock
Joined: Aug 2008
Posts: 757
Northern VA
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Fellas -
So, I need to plug a water pump outlet (for heater hose) in an aluminum water pump. Tapping holes is not something that I do on a regular basis, but I'll bet some of y'all do so I'm asking the experts.
Anyway, the outlet has an ID of .640 and an ID of .880. I'd like to tap it and plug it off with a threaded plug (allen wrench head). I have some plugs and it feels like I could thread one in that's just a tad larger than the ID, but not sure this will be tight enough.
I also have a set of taps and dies, but these are SAE taps (coarse and fine thread). I know that I can use an SAE tap and then thread a bolt inside, but this will look half @$$ed. Can I use an SAE tap and thread a plug into it? Plugs will have NPT threads, right? Just don't know if there is a difference.
Sorry for the 20 questions, but I don't want to mangle this.
Thanks,
Scott
Please Check Out My YouTube Channel for Vintage Musclecar and Truck Rescues and Builds -- https://www.youtube.com/@THEBULLETPROOFGARAGE/videos
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Re: Plugging a Hole - SAE, NPT, WTH?
[Re: bulletpruf]
#1353050
12/17/12 03:32 PM
12/17/12 03:32 PM
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Joined: Jan 2003
Posts: 8,940
Holly/MI
Dean_Kuzluzski
master
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master
Joined: Jan 2003
Posts: 8,940
Holly/MI
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NPT is a tapered pipe thread for sealing.
Your stuff is for straight thread.
A GOOD local harware store will have the tap you're looking for.
Bring in a sample to match it up.
R.I.P.- Gary "Coop" Davis 02/09/68-05/13/04
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Re: Plugging a Hole - SAE, NPT, WTH?
[Re: Dean_Kuzluzski]
#1353051
12/17/12 04:09 PM
12/17/12 04:09 PM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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I'd be wary of plugging it with a plug that fits like a grub screw. Stuffing one of those brass fittings in an aluminum housing rarely ends well. If there's any corrosion you will end up stripping the wrench hole out of that soft brass.
I'd use a plug with a regular bolt style hex head.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: Plugging a Hole - SAE, NPT, WTH?
[Re: bulletpruf]
#1353054
12/17/12 04:47 PM
12/17/12 04:47 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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You're talking about internaly plugging an aluminum male heater hose nipple? Yes you'd want to NPT tap it if you do & not sure if there's enough wall thickness to work with (there might be just never looked at it that way). Much easier would be to get a black neoprene end cap from the HELP section at your parts store along with some gasket cement and a hose clamp. You could paint it engine color to try & hide your handiwork. Functionally it'd be fine
live every 24 hour block of time like it's your last day on earth
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Re: Plugging a Hole - SAE, NPT, WTH?
[Re: bulletpruf]
#1353057
12/17/12 05:29 PM
12/17/12 05:29 PM
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Joined: Oct 2012
Posts: 1,106
Northeast
VincentVega
super stock
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super stock
Joined: Oct 2012
Posts: 1,106
Northeast
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you have .120 wall thick to work with
Looking for 1975 through 1978 B body 4 door sedan sheet metal or parts cars - monaco, fury, coronet. Please let me know
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Re: Plugging a Hole - SAE, NPT, WTH?
[Re: bulletpruf]
#1353059
12/17/12 06:54 PM
12/17/12 06:54 PM
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Joined: Jan 2003
Posts: 75,016
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,016
U.S.S.A.
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Quote:
Quote:
It's NPT tapped hole , you can purchase an NPT plug with an Allen recess in it , go to your local Vatozone , Advance auto or the like and check the fashion performance aisle
I know where to get NPT plugs, but are you saying that I should just thread it in without tapping it first?
Scott
if it is a tapped hole already , which it should be , why would you feel the need to tap it ??? NPT is a TAPERED thread as stated above so you will see 2 different sizes in the hole ...
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Re: Plugging a Hole - SAE, NPT, WTH?
[Re: bulletpruf]
#1353061
12/17/12 07:26 PM
12/17/12 07:26 PM
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Joined: Jan 2003
Posts: 75,016
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,016
U.S.S.A.
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Quote:
Quote:
Quote:
Quote:
It's NPT tapped hole , you can purchase an NPT plug with an Allen recess in it , go to your local Vatozone , Advance auto or the like and check the fashion performance aisle
I know where to get NPT plugs, but are you saying that I should just thread it in without tapping it first?
Scott
if it is a tapped hole already , which it should be , why would you feel the need to tap it ??? NPT is a TAPERED thread as stated above so you will see 2 different sizes in the hole ...
No, it's not tapped already.
Ok I'll ask the REALLY DUMB question , WHAT is this pump for ???
If it's not tapped and you want to tap it with SAE you can BUT you need to drill the taper out of the hole to the proper size for the thread you want to make it or you risk breaking the tap, or the casting , or both.
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Re: Plugging a Hole - SAE, NPT, WTH?
[Re: JohnRR]
#1353062
12/17/12 11:32 PM
12/17/12 11:32 PM
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Joined: Aug 2008
Posts: 757
Northern VA
bulletpruf
OP
super stock
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OP
super stock
Joined: Aug 2008
Posts: 757
Northern VA
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Quote:
Quote:
Quote:
Quote:
Quote:
It's NPT tapped hole , you can purchase an NPT plug with an Allen recess in it , go to your local Vatozone , Advance auto or the like and check the fashion performance aisle
I know where to get NPT plugs, but are you saying that I should just thread it in without tapping it first?
Scott
if it is a tapped hole already , which it should be , why would you feel the need to tap it ??? NPT is a TAPERED thread as stated above so you will see 2 different sizes in the hole ...
No, it's not tapped already.
Ok I'll ask the REALLY DUMB question , WHAT is this pump for ???
If it's not tapped and you want to tap it with SAE you can BUT you need to drill the taper out of the hole to the proper size for the thread you want to make it or you risk breaking the tap, or the casting , or both.
It's a heater hose nipple on an aluminum water pump mounted on a 500 hp 401 AMC in a 71 Javelin street/road race car.
Please Check Out My YouTube Channel for Vintage Musclecar and Truck Rescues and Builds -- https://www.youtube.com/@THEBULLETPROOFGARAGE/videos
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Re: Plugging a Hole - SAE, NPT, WTH?
[Re: Cab_Burge]
#1353065
12/18/12 12:00 PM
12/18/12 12:00 PM
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Joined: May 2005
Posts: 416
Franklin Co. Illinois
runinonmt
mopar
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mopar
Joined: May 2005
Posts: 416
Franklin Co. Illinois
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Now we have a grasp of what you need. If you're doing track days security is your concern. Ream(not absolutely necessary but I recommend it) then Tap the nipple NPT and use a tapered pipe plug with pipe dope(hardware item). Personally, I would cut the nipple close to the water pump before I tapped it. If you're lucky the local hardware will loan the tap and reamer to you. If not check with a machine shop. I believe you will need to tap it 1/2" NPT,3/8 is likely too small. Your hardware will have a plug in the material of your choosing. I recommend brass.
Ron
In sixty-five I was seventeen and running up one-o-one
I don't know where I'm running now, I'm just running on
Jackson Browne-Running On Empty
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Re: Plugging a Hole - SAE, NPT, WTH?
[Re: bulletpruf]
#1353067
12/23/12 11:33 AM
12/23/12 11:33 AM
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Joined: Jan 2003
Posts: 10,720
North Dakota
6PakBee
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,720
North Dakota
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I'm curious, why did you feel it necessary to put the rubber cap over the plug. And that looks suspiciously like an AMC. 401?
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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