Gentles,

I am trying to put together some information on Smiths Fuel Gauges and their application to Austin Sevens,

There is very little "hard" information in the public domain on this equipment.

I am interested in trying to make up a list of the Smiths part numbers for the dashboard mounted "Fuel Gauge" which is usually a letter prefix followed by a series of numbers, and details of any other markings on the dial face, together with any details of the Part Number on the Tank Sender unit. These numbers are usually to be found on the little plate at the top of the sender which covers the "rheostat," or in some cases stamped in the side of the case.

I do appreciate that the Sender is not exactly in a convenient place to readily inspect and extract hieroglyphics from but maybe there are some kind souls out there who have the odd fuel tank and sender neatly stowed in their parts store.

I know that the Fuel Gauge was fitted from the 1932 season right through to the end in 1939, and that two distinct tyopes of set up were used (Low resistance in sender = full tank to begin with, then at some time, probably around 1936, when the High sender resistance = Full tank).

While I am probably the only person in the Realm who would want to know this information, I will be happy to share whatever I find "for the record"

Of course if there is anyone out there who inherited a library containg Smiths Catalogues etc, then I would love to hear from you.

I hope I am not too far whelmed by the response.

Regards

Barry R.

Barry

I looked at my A7 Opal '32.
Fuel guage has the number X30306
Sender is at 6 Ohms no petrol.

I took pictures but have not figured how to put them in this post.
FYI car is an Opal 2 seater, hence much easier to get to the sender unit. Car# B6 9511, chassis 166107

I could not find the number on the sender unit. I will send an email with the pics

Pat in "sunny California" where it is raining 2" per day for the last 3 days!!!!

Thanks Pat,

Have replied to your welcolme email
Something strange about your sender resistance though. Did you read it with lead connected to sender?

If so you are not just reading sender resistance, but also the parallel resistance back into the gauge.

If ever you are in a situation to measure the resistance with lead off would be interested. I would have thought at least 25 "ish" ohms to earth measured at the terminal with the lead off, with the tank near empty.

Regards and thanks

Barry R.

Hi Barry

My info is probably not much help as mines a "bitsa" as you know!
But here goes.....

Tank is off car at the moment and empty. It reads 35.2 ohms including the test leads (about 1 ohm for mine) empty.
If I put it on its side the wiper moves to full and it then reads 20.8 ohms including the test leads.

I cannot for the life of me see anything on the sender despite it being off car??? It is very corroded though so perhaps that expalins it? .
The dashboard gauge which works well with this sender is...
X37650
2H1417
underneath that is "6V"
then the "smiths" logo
then "made in England"

The scale is non linear with "gallons 1,2,3,4,5" marked on it.

Not sure if this helps?

Steve

Thanks very much for that Steve. Yes it is useful. You have just confirmed what I thought about the "X37650
2H1417" as I have come across two different gauges, one with the X37650, and another with the @H1417 on it so they look like they are the same.

Could you tell be, if you know what "sense' your gauge set up is, that is, does it read Full" with the sender in maximum or minimum resistance. Easiest way to test is with battery connected to the B terminal of the gauge and the case earthed, but with no connection to the T terminal, gauge will read "Full" if it is a mximum for Full, or "empty" if it is a Maximum for Eempty" set up.

Are there any numbers on the sender , or is it inaccesible?

Thanks Barry R

Barry

Cant see anything on the sender? I have scraped it clean but still nothing, other than a logo of some kind that is unrecognisable on the top surface of the tank mounting flange. There may have been a tag of some kind maybe?
Gauge is still connected so I havnt tested but I presume that as the sender is at "low" resistance when in full position then the gauge will corrolate to this , as it all works correctly. As a matter of interest I have a 33ohm resistor in series with the battery connection to allow for 12V. I know this is not 100% correct and I should use a simple voltage regulator, but it seems near enough for my needs!!

Regards

Steve.

Steve, if you look in the latest Cornwall Club magazine you will see that early 12v gauges were infact the 6v gauge with an internal resistor in the supply feed to the first coil. You are replicating this but with your resistor externally.

You see ! It has all been done before !

Hi Barry

Have checked my RP manufactured Dec 33 which has gauge with 3 connections B, T, & E
face reads X30406
2H.1079
My second RP about 6 months younger also has X30406 but no other numbers.

Resistance is 17 ohms empty, 1 ohm full. The sender unit has no markings except for the lucas torch logo. My photos of the sender are too blurred but I will take some more (hopefully better) if it will help

Hello you Pearliness!

Thanks for your info.

These senders are coming up as a bit of a mystery.

They are supposed to have Smiths part numbers stamped on the little "oval" plate on the top of the casting, but I haven't yet found one.

Getting further into the Anorak department, can you confirm that your sender unit is the type with the terminal in the longer "side" of the sender raised portion please (some later types have the terminal on the very nuch shorter "end")

Also with your gauge, are the terminals above or (more likely) below the central mounting stud at the rear of course?

Many thanks,

Barry R.

Barry

Photos of the sender and rear of the gauge show your 2 points

No number on the top plate of the sender

position of terminals on the gauge below locating stud

I believe that the senders with the terminal at the end are the reverse type with the oppososite resistance for full & empty

You are indeed a rare jewel, your Pearliness!

Thank for your trouble.

That absolutely confirms for me that you have a G33 type sender (Minimum Resitance for Full indication) and the X30406 gauge as the matching type (terminals below the centre mounting/earth stud at the back of gauge). I think I will start a new topic, and ask a slightly different question as I have not yet had anyone come back with info about the later X42139 gauge which I am fairly confident is the later type which operates Maximum Resitance for full.

Very much appreciate your help.

Barry R.