Oil check petcocks thread size

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Topic author
MudsT
Posts: 2
Joined: Tue Jun 23, 2020 8:55 pm
First Name: Doug
Last Name: McCallister
* REQUIRED* Type and Year of Model Ts owned: 1926
Location: Ovid, Michigan
MTFCA Number: 50114
MTFCI Number: 24799

Oil check petcocks thread size

Post by MudsT » Tue Jun 23, 2020 9:09 pm

Been dealing with drips from my oil check petcocks on my 26 Canadian built coupe. Thought that I'd just change them out with new ones, original style, from Lang's. Removed old petcocks but new ones seem to be larger diameter and will not screw in. Anyone have an idea why this might be such a problem? Difference between USA and Canadian built. Lang's part issue?


Scott_Conger
Posts: 6428
Joined: Sun Jan 06, 2019 11:18 am
First Name: Scott
Last Name: Conger
* REQUIRED* Type and Year of Model Ts owned: '13, '15, '19, '23
Location: Clark, WY
Board Member Since: 2005

Re: Oil check petcocks thread size

Post by Scott_Conger » Tue Jun 23, 2020 11:02 pm

1/8 NPT is a tapered thread. There is some chance that the die was not threaded on far enough, I suppose.
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves
Obsolete carburetor parts manufactured


Topic author
MudsT
Posts: 2
Joined: Tue Jun 23, 2020 8:55 pm
First Name: Doug
Last Name: McCallister
* REQUIRED* Type and Year of Model Ts owned: 1926
Location: Ovid, Michigan
MTFCA Number: 50114
MTFCI Number: 24799

Re: Oil check petcocks thread size

Post by MudsT » Wed Jun 24, 2020 6:08 pm

Scott,
I picked up a die for that thread. After some iffy starts I did manage to run the die down further than threads supplied. Reversed the die and chased threads further. Now catching several more threads and new petcocks will work. Thanks again great info. Doug


Scott_Conger
Posts: 6428
Joined: Sun Jan 06, 2019 11:18 am
First Name: Scott
Last Name: Conger
* REQUIRED* Type and Year of Model Ts owned: '13, '15, '19, '23
Location: Clark, WY
Board Member Since: 2005

Re: Oil check petcocks thread size

Post by Scott_Conger » Wed Jun 24, 2020 6:36 pm

I'm glad it worked, but it is a tapered thread and the die is not reversable and still get the designed thread. If it doesn't drip, then no harm no foul and am glad you're moving forward with your project.
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves
Obsolete carburetor parts manufactured

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