Sending unit size

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Duster2022!

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So I’m doing the 440 swap into my 72 duster. I am in the process of purchasing a new fuel tank. I was told that I may need to run a bigger sending unit in the gas tank? If so, what is a recommended size that works best?
 
I think the stock sender has 5/16 tube.

3/8 would be a step up.

Just know your fuel gauge will never read correct
 
Depending on how "HOT' your 440 is, the stock 5/16" sender and line will work ok. You can increase to 3/8" but you will need a sender, new line, fuel pump with proper sized inlet and outlet and the line up to the carb with a different filter of course.
 
Well, I plan on having new gauges built so I think the new gauges could be built to accommodate a 3/8 sender
 
I've had several big block cars that worked fine with 5/16" fuel line. To get the benefit of the 3/8" line, you'll need to change the steel line, too. I'd try and see if you need it before upgrading. You'll only notice a fuel starvation at higher RPMs. If you don't have a problem, no need for the extra work.
 
It’s a mild build for 40 about 550 horse. And it’s only going to be used around town and to local car Cruzans not planning on driving it on long distances.
 
Also remember that length of a tube/ hose is also important for restriction. Just how much power to you anticipate? If you think you are on that edge, you can actually run "let's say" a 3/8 tube/ hose system, but still use the 5/16 sender with little restriction for that short length.

Pumps will make a difference, as well. A rear electric pump is going to suffer much less loss pumping into a 5/16 tube than an engine mount pump trying to "suck" all the way from the tank. This is simple. It's because pushing the fuel is at higher pressure than trying to suck it, so the loss is not as great an effect
 
67Dart273 said:
Also remember that length of a tube/ hose is also important for restriction. Just how much power to you anticipate? If you think you are on that edge, you can actually run "let's say" a 3/8 tube/ hose system, but still use the 5/16 sender with little restriction for that short length.

Pumps will make a difference, as well. A rear electric pump is going to suffer much less loss pumping into a 5/16 tube than an engine mount pump trying to "suck" all the way from the tank. This is simple. It's because pushing the fuel is at higher pressure than trying to suck it, so the loss is not as great an effe
Click to expand...
 
So you recommend that I just keep the 5/16 fuel line and sending unit and running electric fuel pump
 
just to be sure I got a 3/8 line with my new fuel sending unit, original was 5/16
it was $75 a yr ago
 
Duster2022! said:
So you recommend that I just keep the 5/16 fuel line and sending unit and running electric fuel pump
Click to expand...
It's up to you. If you want to point at the fuel line and tell people it's 3/8", go ahead and upsize it. For the purpose you said you plan to use the car, a stock fuel system with mechanical pump should be fine. You'll need the larger fuel capacity at higher RPM. Where I live, if you spend much time at 5000+ RPM at cruise ins, you'll be asked to not come back. And on the street, you'll be asking for tickets.

I would install a vapor return system if there isn't one already.
 
Duster2022! said:
Thank you. What’s a good company making sending units?
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No one really makes "good" senders. Very few are accurate without using a Meter Match or the like. I have never used a aftermarket gauge so I don't know how they mate with a stock sender. Something you will need to do some homework on.
 
Spectra makes quality stuff. Mostly Canadian, so much much better than Chinese.

Spectra FG69B is a sending unit with a 3/8" pickup and has a vapor return port. You can neck down the 3/8" to match your factory line. Plug the port if you don't have a return line yet. If you have a starvation problem, you can upsize your hardline as necessary. Running a vapor return will help fight vapor lock. I don't know, but your '72 may have a return line already installed. To get the gauge to read correctly may require use of a meter match or similar device. I don't have any direct knowledge on those, but there are plenty of threads about them here on FABO.

Spectra CR11E is a quality tank. It costs more than the Chinese tanks for good reason. But it's still not crazy expensive.

Shop around for the best price. Rock Auto usually has a good price, but you'll pay shipping. Summit Racing costs a little more, but includes free shipping at $119 (I think). The free shipping threshold has moved around in the past couple of years. Shipping on a tank could be a lot, so where you buy it could significantly affect your total cost.

There are issues with the lock ring and gasket not always fitting. If this happens to you, get the Detroit Muscle Technology (DMT) kit.
Mopar 57-78 Sending Unit to Gas Tank Seal and SS Lock Ring Locking Retainer

If I were in your situation, this is what I would do. Good luck!
 
S'cuder said:
Spectra makes quality stuff. Mostly Canadian, so much much better than Chinese.

Spectra FG69B is a sending unit with a 3/8" pickup and has a vapor return port. You can neck down the 3/8" to match your factory line. Plug the port if you don't have a return line yet. If you have a starvation problem, you can upsize your hardline as necessary. Running a vapor return will help fight vapor lock. I don't know, but your '72 may have a return line already installed. To get the gauge to read correctly may require use of a meter match or similar device. I don't have any direct knowledge on those, but there are plenty of threads about them here on FABO.

Spectra CR11E is a quality tank. It costs more than the Chinese tanks for good reason. But it's still not crazy expensive.

Shop around for the best price. Rock Auto usually has a good price, but you'll pay shipping. Summit Racing costs a little more, but includes free shipping at $119 (I think). The free shipping threshold has moved around in the past couple of years. Shipping on a tank could be a lot, so where you buy it could significantly affect your total cost.

There are issues with the lock ring and gasket not always fitting. If this happens to you, get the Detroit Muscle Technology (DMT) kit.
Mopar 57-78 Sending Unit to Gas Tank Seal and SS Lock Ring Locking Retainer

If I were in your situation, this is what I would do. Good luck!
Click to expand...
Greatly appreciate it!!!
 
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