DDK - Die Deutschen Klassiker

Here's one for you, does anyone know what the ohm rating is for the fuel tank sender on a B T6. I'm fitting an aftermarket fuel gauge but there are 5 types from which I can choose each with differing ohm ratings. Or perhaps one of you boffins could explain how one can determine the ohm rating of my sender.

Jeez, help me out guys, I have the fuel tank on the bench with the sender alongside and a multimeter ready to click of those ohms. Do you think I should wire the sender up as per the wiring diagram to get a reading, or maybe I should forget the gauge and just get a stick with some notches on it . . .full, half full, half empty, not much left, you're walking pal.

Maybe try a PM to Tim, Impmad2000, he's helped a lot of folks with electrical issues - I'm afraid car electrics are a complete mystery to me

Just connect it properly and remember to earth the case. Move the arm up and down and see what the gauge reads. There is nothing else you can do.
John

John is right. I had a look through the workshop manual and other technical books I have last night. No info in them to help you though.

Looking in the Stoddard catalog they define 356 pre A, late 356A and 356BT5 as "arm type sending units. The 356BT6 up to chassis 121223 coupe as a cylinder type?
I had a 356C long ago and from memory it still had an arm type becuase it was an early 63 one.

Do you have an arm on yours?

Roy

Sorry, I cant help much with this, I have no 356 bits I can measure, but can read off a 911 gauge sender if necessary.
Any circuit diagrams or photos may help me though. How many connections to the sender ?
If you can identify the resistive track, you can measure this with the multimeter, I'd guess a few hundred ohms at one end and near short circuit at the other. From this it is just a matter of "best fit" from the after market ones available. What options do the after market gauge people offer ?
Happy to help if I can.
Cheers
Tim

The workshop manual has a wiring diagram, but no other information on it.

Thanks very much guys, I was also unable to get any specs or information from my Porsche library on this, so I hooked it up as per wiring diagrams but was unable to obtain a specific reading however much I tried. As I have the fuel tank out of the car what I shall do is cut the existing sender base from the tank and weld in a new sender which will be the correct 240 ohms empty and 33 ohms full rating. It's a bit more work but this will be compliant with the gauge. The instrument in question is an Autometer Ultralite, they do a nice range of full sweep electrical gauges.

Looking in the Stoddard catalog they define 356 pre A, late 356A and 356BT5 as "arm type sending units. The 356BT6 up to chassis 121223 coupe as a cylinder type?
I had a 356C long ago and from memory it still had an arm type becuase it was an early 63 one.

Early T6 tanks had the sender at the bottom of the tanks with the cylinder type sending unit. then changed in about '63 to the top arm type.

So your early 'c' was in fact a late T6.