drake fuel gauge
- Thread starter fordman
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flatheadmurre
Well-known member
So whats not correct...showing wrong level but right span(0 to full)=bend the floatrod.
Way off in the span...showing below 0 and over full=you can adjust the intrument a bit perhaps shorten or lenght the floatrod a bit.
If the readings are all over the place cause its a crappy resistive meter thats wound incorrect=put it under the wheel drive it over and get a better sender.
Way off in the span...showing below 0 and over full=you can adjust the intrument a bit perhaps shorten or lenght the floatrod a bit.
If the readings are all over the place cause its a crappy resistive meter thats wound incorrect=put it under the wheel drive it over and get a better sender.
19Fordy
Well-known member
This topic has been well researched. The OEM sending unit does not operate on the Ohms Principle. Pour yourself a cup of coffee and read these threads.
http://www.fordbarn.com/forum/search.php?searchid=6911702
http://www.fordbarn.com/forum/search.php?searchid=6911702
Hi there, the original ford tank sender unit is a King Sealy made unit that has a set of switching contacts and a bi-metal with a heater coil winding. It works the dash gauge by switching on and off at different rates depending on the fuel level. The more modern Drake unit works on a variable resistance system and is in most cases not combatable with the original gauge. The old tank units can sometimes be repaired. Corrective plan for you is to remount the original tank sender into your new tank. There is an adaptor plate which I THINK can be used for this fit up. Regards, Kevin.
Bob-93021
Member
Kevin, That was the most simple explanation I have read on why the 2 different operating system are incompatible! I wish that someone could pull together a comprehensive book on auto type gauges covering OEM and aftermarket stuff for us. Thanks - Bob
flatheadmurre
Well-known member
The KS used in the early fords are a balance system, you have 2 identical bimetals heated at the same time with points in the sender opening when you reach a sertain level.
Then both cools down until the poinst close again.
This way you get a mirror image of the senders bimetal in the meter.
It´s not pulses in the meaning being 2 a minute or something like that.
Exactly the same type of meter works just fine with a resistive sender if the bimetal is designed with a movement linear to the current aplied to it.
The balance system is very clever in the way you dont need to design the bimetal in any other way then keep a good quality so they act the same.
Then both cools down until the poinst close again.
This way you get a mirror image of the senders bimetal in the meter.
It´s not pulses in the meaning being 2 a minute or something like that.
Exactly the same type of meter works just fine with a resistive sender if the bimetal is designed with a movement linear to the current aplied to it.
The balance system is very clever in the way you dont need to design the bimetal in any other way then keep a good quality so they act the same.
19Fordy
Well-known member
So, it seems that in the case of the operation of the KS gas guage, if a resistor is installed in a newer style gas tank sending unit, the OEM guage won't work accurately because it's original bi-metal component is NOT designed with a movement linear to the current applied to it.
It would be great if there was a way to accurately remedy this problem. The key word is accurately.
It would be great if there was a way to accurately remedy this problem. The key word is accurately.
flatheadmurre
Well-known member
There are a few issues with using a resistive sender.
First early fords have a very low ohm range about 70 if i remember right.
This means a resistive sender gets less accurate cause a small movement makes a big change in current.
Modern resistive units are usual higher range like 240 ohm.
Trying to wind a logaritmic sender with low resistanse means you have to use a lot of thick wire and that is expensive and difficult to fit in the sender.
Not to mention someone has to measure the caracteristics of the meter first to find out how it behaves at different current levels.
Is there a big enough market to make someone develope a product like this...not from a profit point of view i guess.
First early fords have a very low ohm range about 70 if i remember right.
This means a resistive sender gets less accurate cause a small movement makes a big change in current.
Modern resistive units are usual higher range like 240 ohm.
Trying to wind a logaritmic sender with low resistanse means you have to use a lot of thick wire and that is expensive and difficult to fit in the sender.
Not to mention someone has to measure the caracteristics of the meter first to find out how it behaves at different current levels.
Is there a big enough market to make someone develope a product like this...not from a profit point of view i guess.
