Petrol Tank Sender Units

[Ian Anderson]

My SC Jupiter was built in 1956 entirely from new parts purchased from Jowetts after the factory closed. If my new ignition coil (see other post) continues to start the car as well as it does at the moment, I really need a more accurate fuel gauge. Whether Mr Townend was unaware that the tank sender is different on an SC, or was just unable to source one, I assume that I have an SA sender unit. I seem to remember that the SA has a wide, shallow tank, whereas the SC has a narrower, deeper tank, needing a longer arm on the float. The result is that the petrol guage reads accurately at half full. but most of the time says full or empty.
I don't suppose for a minute that anybody has an SC sender unit lying about, so I am probably going to need to extend the arm somehow. but then will it be too heavy for the float? Has aybody tried such a procedure?

Ian Anderson

[jowettgeoff]

I don't think the extra arm length will prevent the float from er floating Ian! Might be worth checking that the resistance is the same though. I've checked the one from (son) Richard's SC and it swings from 0 ohm to around 100 ohm.

Geoff.

[RichardMc]

.......
I don't suppose for a minute that anybody has an SC sender unit lying about, so I am probably going to need to extend the arm somehow. but then will it be too heavy for the float? Has aybody tried such a procedure?

Ian Anderson

Hi Ian, Holden do a side mount sender (070.012) for £34 ex VAT that looks very similar and is suitable for Smiths gauges. I'm working on my SC tank this week and have the factory sender on the bench. I'll do some measurements and post some pictures, as the boss said it reads between 0R and 100R but it is a bit erratic. I might change mine while everything is in bits.

[Keith Clements]

You should find as the sender is used it will become less erratic as corrosion is rubbed off wire.
Modern gauges are likely to be less reliable due to location of manufacture.

[jowettgeoff]

Location of manufacture could be an issue. I've just bought a 'Lucas' DM2 distributor cap from Holden for £33 incl. carriage, which I expected to be a genuine item. What I received was a poorly made Taiwanese replica. It's going back today for a refund. I've now ordered a couple from ESM Morris Minors for only £11 each, but I fear these might be replicas too. Watch this space!

[Keith Clements]

Get your Dizzie from Distributor Doctor and ask for my spec of advance curve.

[Srenner]

And do not use a new black rotor, get a red one. There is a thread somewhere about this; carbon black is cheaper than resin so the rotors are conductive.

[jowettgeoff]

Just received the new cap from EM Morris Minors. Better than the one that Holden sent me (and cheaper too), but not a patch on the original bakelite Lucas ones. We'll see how it performs. The carbon brush is thinner, as are the bayonet screws. And the four 'contacts' are steel rather than brass.

[RichardMc]

Back to the subject of this thread (start your own on dizzy caps and rotor arms!)
Details for the SC fuel tank sender.
Arm length 12 1/2" Inches from pivot point to float centre
Sender base plate is 2 3/8" PCD
The screws look like a BA thread but I didn't check

[Keith Clements]

Take care. From memory the screws are Whit. I have a faint recollection that they broke and needed retapping on Amy's SC.

[RichardMc]

Take care. From memory the screws are Whit. I have a faint recollection that they broke and needed retapping on Amy's SC.

Cheers Keith, I'll watch out of that.

[Keith Clements]

viewtopic.php?f=163&t=2722&p=17575&hilit=sender#p17575

3BA

Knew it was recorded somewhere.

[Ian Anderson]

Many thanks to all who posted replies. Nobody replied originally, so I just went ahead and removed the sender unit which tested OK. The arm, however was (I think) only about 8" long, so the tank was 1/3 full before the fuel even reached the float. By sticking a steel tape measure through the hole into the tank I guessed that the arm needed to be just less than 13" long (confirmed after the event by Richard Macaulay). I stripped the flux off an old arc welding rod, cut the arm and MIG welded the rod in to extend the arm. It looked a bit rough and ready, but it's about as out of sight as you can get and my fuel gauge seems to work properly.