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Temperature gauge adventure

Posted: Fri Sep 25, 2026 1:19 am
by Rabbitt
IMG_1953.jpg
IMG_1953.jpg (50.68 KiB) Viewed 391 times
Something supposed to be simple , but maybe it isnt. A bit of a rabbit hole :D
I have a 1957 803cc series II Positive Earth here in NZ.
1 : Have done my homework in the forums but probably only got a D- mark. Definitively , will a Smiths Temp gauge operate in a positive earth car. appears that the answer is NO ! I do have a voltage regulator but that overall option seems a dead duck.
2. So I have bought a mechanical gauge as suggested but of course there is no engine block source to tap into , therefore a radiator hose adaptor is required , which I have also purchased.
3. A couple of difficulties ... the sender bulb is too large for the adaptor insert hole tap (NTP) and most of these adaptors have a default thread size.
Also , even if the insert thread was correct for the sender bulb and it was possible to screw home , the end of the bulb would bottom out against the other sidewall of the adaptor itself. (even if the supplied thread adaptor is used giving more length.) So the sender is both too wide and too long !
Any ideas ?

Re: Temperature gauge adventure

Posted: Fri Sep 25, 2026 8:05 am
by philthehill
Get the right adapter !!.
If your hose internal dia is 25mm as I suspect it is having just measured a Minor top hose then this is the adapter you need with the 5/8" UNF thread.
https://www.merlinmotorsport.co.uk/p/25 ... aptor-ha25

You may need one of these to space the transmitter way from the hose adapter.
https://www.moss-europe.co.uk/adaptor-t ... -3-11k2846