[Healeys] One for the thread guys

[John Spaur]

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>
Cc: 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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