The sender I posted about last year is the Summit sender.  While it works it will never read empty.  If you look at the other post I have the sender in a test stand next to the fuel gauge and you can see it never reads empty. best I could do was a little under 1/4 with the arm all the way down.

The wiper that the float moves is off the  wire wound part of the of the resistor when the float is all the way down so no amount of arm bending will make it go lower.  The resistor winding is just not right for the application.  If you could live with saying your tank is empty when the gauge falls below 1/4 the sender will work but I would want better than that.

I am still going to investigate repairing the original sender or re calibrating the gauge empty point, I am told it can be done.

From the thread 4 months ago:

"The King-Seeley system does not work on "resistance"!!!!  The shop manual has a good basic description of its workings.

It works on a system of heating elements and bi-metal-springed points affected either by pressure [in the case of the fuel sender], or heat [in the case of the engine temperature gauge system.
You MAY be able to get a correct range of resistance on an aftermarket sending unit by "fudging" around; however, you can't just measure the sender or gauge resistance and expect to "match" it; it's an entirely different operating principle.  To do that, use a variable power resistor of a range from about 20 ohms to about 500 ohms (or some select individual power resistors in that same range), set it at it's maximum resistance range, and insert into circuit IN PLACE OF the sending unit, then carefully and very slowly (over several minutes of time - the gauge is very slow acting) start to reduce the resistance 'till you just notice the gauge coming off of "empty"; then take the resistor out of circuit and measure the resistance: That will be your "high" range end of resistance needed. Re-insert the resistance into the circuit and, again, very slowly start reducing it's resistance until you just "hit" the "full" gauge mark; then re-measure the resistance of the variable resistor: That will be your "low" range end of resistance needed. [You could also try this at "mid" range just to get some idea of  your "system's" non-linearity, if you want.]  Now you can try to locate an aftermarket "resistance" sender to meet your needs.  EDIT: Please note that you need to ind an aftermarket sender that is at it's "high" end of resistance when the float is dropped for empty, and is at it's "low" end of resistance when the float is high for "full"; some senders might be "backwards" from what you need!!!

NEVER apply the full 6 or 12 V to the gauge directly: It will burn out in fairly quick order - this is why you start the resistance check at it's highest resistance!

I've adapted my '55 6V system to a 12 V conversion by using the original sender/gauge SYSTEM, measuring the TOTAL SYSTEM resistance (mine measured about 35 ohms), and adding an equivalent series  power resistor in series with the sender/gauge circuit (I "hid" my resistor just under the fuel tank sender access plate in the trunk floor).

In a case like mine [using the original King-Seeley 6V system in a 12 V conversion - NOT the same as the 3rd paragraph above explains in detail for "aftermarket"], the MINIMUM power dissipation rating of the 12-to-6V dropping resistor MUST be figured by calculating the current draw using the circuit voltage-drop (6V  --  to drop 12 V to 6 V) divided by the measured resistance (35 ohms in my case) to equal 0.171 Amps [171 mA]; then, taking the voltage drop (6 V) times the calculated current draw (0.171A) which calculates to 1.08 Watts. OR using the voltage drop squared [6*6=36] divided by the circuit resistance [35 ohms] gives essentially the same answer for minimum power dissipation [in watts].

Because of the "intermittent" (continually opening and closing) nature of the sender points in this King-Seeley system, a 1 Watt resistor is probably "adequate", though a two or 5 watt resistor might be more reliable over time for this specific application. You MUST calculate the above for YOUR system; I only used my system for my calculations as an example of how to do it; and, it may NOT fit your system.  As usual: It's YOUR responsibility as to whether or not to try and use the above information for YOUR use.
I hope that this information is helpful to others.

Regards, JLB"

I am surprised the old points style 6 volt reducer works with the King Sealey type gauge as the system does not draw continuous current due to the opening and closing of the points in the sending unit.  The solid state type should work fine

FWIW (remember - "free" advice here), the solid state regulators would be good IF their regulation was good, consistent, and reliable; most that are available to us in the "classic car" consumer market are not; they are made very cheaply and expensively priced.

Having retired from 45+ years of working in precision electrical/electronics (NOT "consumer" stuff - a lot of which is "junk" - which I have also worked on for myself, friends, and family), I would not personally use one of the old "points" regulators as they can be notoriously "out of calibration", and the points can weld shut - passing the full 12 volts through.

I've also seen way too many "consumer-quality" solid-state type regulators fail catastrophically - and, would not trust them on my own system to not "burn-out" the sender/gauge circuit by failing and passing the full 12 volts through to the 6V gauge system.  Using my resistor technique protects these old systems from very serious potential damage.  I simply won't take the chance with my own by using other methods - too expensive and difficult to replace them if damaged!  That's why this thread in the first place.

Using a measured and calibrated resistor as described will usually fail only one way: Open-circuit; and, will not harm the circuit in any way if properly applied. Besides, it's the simplest solution: Just put the "right" resistor in series with the gauge circuit [anywhere between battery accessory feed and ground], and go. And it's not polarity-sensitive (works equally well with + or - ground systems).

The measurement is actually very simple: Just measure the complete circuit resistance (unpowered, with the power feed connection completely disconnected between the ignition switch and gauge circuit [so as to not be measuring "other" things too]) between gauge power connection and ground (mine was around 35 ohms), and match it with a, say, 5-watt-rated power resistor of [or close to] the measured circuit resistance.  I only went into all the detail to benefit those that want to know those measurements and calculations.

Same holds true for the temperature gauge circuit.

Regards, JLB

FWIW (remember - "free" advice here), the solid state regulators would be good IF their regulation was good, consistent, and reliable; most that are available to us in the "classic car" consumer market are not; they are made very cheaply and expensively priced.

Having retired from 45+ years of working in precision electrical/electronics (NOT "consumer" stuff - a lot of which is "junk" - which I have also worked on for myself, friends, and family), I would not personally use one of the old "points" regulators as they can be notoriously "out of calibration", and the points can weld shut - passing the full 12 volts through.

I've also seen way too many "consumer-quality" solid-state type regulators fail catastrophically - and, would not trust them on my own system to not "burn-out" the sender/gauge circuit by failing and passing the full 12 volts through to the 6V gauge system.  Using my resistor technique protects these old systems from very serious potential damage.  I simply won't take the chance with my own by using other methods - too expensive and difficult to replace them if damaged!  That's why this thread in the first place.

Using a measured and calibrated resistor as described will usually fail only one way: Open-circuit; and, will not harm the circuit in any way if properly applied. Besides, it's the simplest solution: Just put the "right" resistor in series with the gauge circuit [anywhere between battery accessory feed and ground], and go. And it's not polarity-sensitive (works equally well with + or - ground systems).

The measurement is actually very simple: Just measure the complete circuit resistance (unpowered, with the power feed connection completely disconnected between the ignition switch and gauge circuit [so as to not be measuring "other" things too]) between gauge power connection and ground (mine was around 35 ohms), and match it with a, say, 5-watt-rated power resistor of [or close to] the measured circuit resistance.  I only went into all the detail to benefit those that want to know those measurements and calculations.

Same holds true for the temperature gauge circuit.

Regards, JLB