for sure can't have only one thread of engagement.
but don't go tapping.
tapered thread right ?
turn it in until there's some resistance.
don't use teflon tape on the threads...as that's an electrical connection -
the OP switch has to make ground in the engine block.
you should get 4 turns maybe.

----- Original Message -----
From: "Rocket J Squirrel" <camping.elliott@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, May 27, 2011 5:37 PM
Subject: Re: Torque spec that requires calibrated fingers

> Thanks for the tip, Mike!
>
> I just received my Autometer oil temp senders and tried one in a
> fitting. They are 1/8'' NPT threads and "finger tight" is only about one
> turn. It worries me to have only one turn of thread engagement. I'm
> tempted to go at the threads with a tap and die.
>
> On Fri, 2011-05-27 at 19:57 -0400, Mike S wrote:
>
>> >warning light sender has this to say about torquing:
>>
>> Well, for regular bolts/screws, with experience one does develop a
>> "mechanic's feel," where you can feel when the bolt starts to stretch
>> and full "torque" is achieved. (I quote torque because it is an
>> indirect measure of clamping force, which is the real concern).
>>
>> Pipe fittings are a bit different, since they seal instead of clamp, so
>> the feel is completely different. Most people tend to vastly
>> overtighten them. "Hand" tight, plus a quarter turn is probably a good
>> start. If it leaks, give it another quarter turn.