I think Castle Auto Electrics have the weld in ring. You can make a VN sender operate a HZ gauge but I think the HG are a thermal type like a HQ and may not work.

thanks fella's.so that would mean i keep the hg sender in the tank where it is and fit the vt pump set up next to it.im guessing i can just remove the float set up on the vt pump.just need a weld in ring now.had a look on Castle Auto Electrics site and it looks like they sit the vt pump next to the hg sender on their ready modified tanks.

FX to mid-HQ have magnetic gauges with a fuel sender which read 0 ohms empty & 30 ohms full.

Mid-HQ to WB (commercials) gauges are thermal & their senders read 73 ohms empty & 10 ohms full.

WB Statesman & all Commodore pre-VYII (also thermal) read 282 ohms empty & 40 ohms full.

VYII onwards (digital since VT) just reversed & went 40 ohms empty & 282 ohms full.

As the others have said pete11, use the weld ring in the top of the tank & fit a VT style pump assembly. Remove & delete the VT sender & make sure the VT pump is located so that it does not interfere with the HG's fuel sender float arm.

The beauty of using the VT pump assembly is that it is fully self contained, so no need for surge tanks or pre-pumps & they are very quiet in operation. They also have provision for the return line from the pressure regulator.

They have a normal service life expectancy of over 250,000km & are reasonably priced.

I sell the genuine article to the trade for less than $150 (incl. GST). I also sell the fancy quick-release type fuel line fittings to suit. Where are you located ?

Dr Terry

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Originally posted by HK1837

quote:

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Originally posted by gm5735
The senders are not interchangeable. The resistances of the sender rheostats are completely different, and in the opposite direction from each other.
VN resistances are:
Empty: 282 ohms
Half: 97 ohms
Full: 40 ohms.
HKTG resistances are:
Empty: 0 ohms
Half: 16 ohms
Full: 31 ohms.

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I thought they were like an early HQ and back to front compared to the later gauges.

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Correct. I think that's what I wrote.
The HKTG and up to 9/73 HQ gauges have two coils and indicate based on the imbalance between those coils. One of the coils is connected to the sender and responds to the current through it, and the other coil is connected to +12V and has a constant current flowing through it.
More imbalance = more needle deflection.
When the sender has 0 ohms, at empty, the same current flows through each of the gauge coils and the gauge reads zero. When the sender is at maximum resistance, (when the tank is full) the imbalance between the coils is maximum, and the gauge reads maximum, or full. Higher resistance = higher needle deflection. They are also fairly linear.
The HQ thermal responding gauges require more heat to move the needle further up the scale. For this reason the sender reduces resistance as the fuel level increases, giving more current to the thermal element in the gauge and a higher needle reading.
Less resistance = more needle deflection.
They are not as linear in response and dislike being shorted to ground, but do have better damping.

Edited by user Sunday, 7 June 2015 7:12:59 AM(UTC)  | Reason: Not specified