[Healeys] One for the thread guys

[John Spaur]

I read that it is a 5/8 bolt, so I am a little uncertain now. The last time
I replaced the bulb was 11 years ago. Also, I don't recall that there was a
copper washer which would be needed. Could it be a pipe thread?

 

From: WILLIAM B LAWRENCE [mailto:ynotink at msn.com] 
Sent: Sunday, June 2, 2024 12:58 PM
To: John Spaur via Healeys <healeys at autox.team.net>; 'Michael Salter'
<michaelsalter at gmail.com>; 'Mirek Sharp' <m.g.sharp at sympatico.ca>; John
Spaur <jmsdarch at sbcglobal.net>
Subject: Re: [Healeys] One for the thread guys

 

However the "UN" denotes a unified thread which is the same as SAE.

  _____  

From: WILLIAM B LAWRENCE <ynotink at msn.com <mailto:ynotink at msn.com> >
Sent: Sunday, June 2, 2024 7:55 PM
To: John Spaur via Healeys <healeys at autox.team.net
<mailto:healeys at autox.team.net> >; 'Michael Salter' <michaelsalter at gmail.com
<mailto:michaelsalter at gmail.com> >; 'Mirek Sharp' <m.g.sharp at sympatico.ca
<mailto:m.g.sharp at sympatico.ca> >; John Spaur <jmsdarch at sbcglobal.net
<mailto:jmsdarch at sbcglobal.net> >
Subject: Re: [Healeys] One for the thread guys 

 

I believe the "S" denotes a straight thread as opposed to tapered.

  _____  

From: Healeys <healeys-bounces at autox.team.net
<mailto:healeys-bounces at autox.team.net> > on behalf of John Spaur via
Healeys <healeys at autox.team.net <mailto:healeys at autox.team.net> >
Sent: Sunday, June 2, 2024 7:13 PM
To: 'Michael Salter' <michaelsalter at gmail.com
<mailto:michaelsalter at gmail.com> >; 'Mirek Sharp' <m.g.sharp at sympatico.ca
<mailto:m.g.sharp at sympatico.ca> >
Cc: healeys at autox.team.net <mailto:healeys at autox.team.net>
<healeys at autox.team.net <mailto:healeys at autox.team.net> >
Subject: Re: [Healeys] One for the thread guys 

 

When I rebuilt the engine in my 1962 BT7 I cleaned the threads with a
9/16-18NF tap. When I reinstalled the bulb I used Hylomar, possibly the
hardening type, to seal the threads. No leaks.

 

John

 

From: Healeys [mailto:healeys-bounces at autox.team.net] On Behalf Of Michael
Salter
Sent: Sunday, June 2, 2024 10:42 AM
To: Mirek Sharp <m.g.sharp at sympatico.ca <mailto:m.g.sharp at sympatico.ca> >
Cc: healeys at autox.team.net <mailto:healeys at autox.team.net> 
Subject: Re: [Healeys] One for the thread guys

 

I don't have a 55 degree 16 TPI thread gauge but my 60 degree seems to be a
very good fit.

 

On Sun., Jun. 2, 2024, 12:45 p.m. , <m.g.sharp at sympatico.ca
<mailto:m.g.sharp at sympatico.ca> > wrote:

Bit of a stumper Mike.  Tracy tools, my go-to source for taps and dies, sell
a tap that is 5/8"x16 with a "UNS" thread form
https://www.tracytools.com/product/5-8-x-16-tpi

I am unfamiliar with UNS but believe it is the abbreviation for Unified
National Special, suggesting it is non-standard thread.  Looks like a bit of
a rabbit hole and I am curious to see what others find.

 

From: Healeys <healeys-bounces at autox.team.net
<mailto:healeys-bounces at autox.team.net> > On Behalf Of Michael Salter
Sent: Sunday, June 2, 2024 10:26 AM
To: healeys at autox.team.net <mailto:healeys at autox.team.net> 
Subject: [Healeys] One for the thread guys

 

The thread on the flare nut used to secure the temperature bulb into the
head on later 6 cylinder engines is 5/8" diameter and 16 TPI.

Is this some sort of standard thread or a "special"?

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