[Mgs] MGB gas-tank dipstick

[PaulHunt73]

The gauge markings aren't linear because the sender characteristics are 
not linear, despite the resistance wire former changing width at one 
point i.e. the length of each turn and the windings changing from single 
to double at another i.e doubling how much resistance is added/removed 
for a given movement of the float.  The result is that the gauge 
markings are *about* right, although both of mine drop rather suddenly 
towards one quarter shortly after they have passed half.

There were two tank necks, it is possible that one doesn't allow a 
straight dipstick, but you could still use a weight on non absorbent 
string to get an approximate depth for the purposes of seeing whether 
the gauge is way out or not,  which was the object of the exercise as 
far as I can remember.

The gauge is only a reminder that it might be time to fill up on a long 
run - it's not like a temp or oil gauge which might exhibit a sudden 
change and be a harbinger of bad news - and each time you do it 
shouldn't be beyond the wit of man to compare what the gauge said when 
you stopped and if you brim it how much fuel went in.

Changing the sender willy-nilly when you have now idea what is wrong, or 
indeed if anything *is* wrong, does not appeal to me at all.

PaulH.

On 06/01/2023 18:16, Max Heim wrote:
> I additionally wanted to point out why the dipstick method is 
> practically useless. If you look at the fuel gauge markings on a Mk. I 
> MGB, you will see that the scale does not consist of even increments — 
> each “quarter” is a different size — it is not remotely a linear 
> scale. So any dipstick reading is no more than a wild guess. You could 
> determine the difference between a mostly full tank, a partial tank, 
> and a very low tank, but that’s about it.