themechanic
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If the fuel gauge was linear it is easy to calculate but it's not.
How many gallons in a 1/4 tank of gas?
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Look up the capacity spec of whatever type of vehicle you have in mind and divide by 4.
themechanic
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That's what I said is correctly calculated assuming the gauge is linear. Correct me if I'm wrong but isn't the gauge non-linear?
My tank is 19 gallons and is wedge shaped.
69 Coronet
My 1970's Mopars seemed to be fairly linear.
GM's of the same era and into the 1980's were definitely not linear.
***
I have seen conflicting capacities for my '79 300, but I once fueled it with 22 gallons.
GM's of the same era and into the 1980's were definitely not linear.
***
I have seen conflicting capacities for my '79 300, but I once fueled it with 22 gallons.
I do not believe the sending unit rheostat is wired to accurately reflect the shape and volume of the tank at all levels. If it's a 16 gal tank, the last 5 gals might show as a quarter.
Or something else.
Thanks for that, post #3 and 16 are the good take aways. Looks like they did try tailoring the winds to the changes in in volume/ height.
autoxcuda
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When tanks gets to 1/4 full, then fill it up.
Take that amount you filled it up and subtract from the 19 gallon tank.
If you want to know 1/2 full, same thing...
Take that amount you filled it up and subtract from the 19 gallon tank.
If you want to know 1/2 full, same thing...
Bear in mind also that the float is in the deepest part of that shape of a tank. So 1/4 (which = approx 4.5 gallons) might show as a lot less than a quarter of a tank.
It also depends upon the stance of the car and whether or not the driver is in his/her/they/them seat.
It also depends upon the stance of the car and whether or not the driver is in his/her/they/them seat.
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Sending units can also be shaped wrong. This A body sender and tank.....
The float was at least 1 1/2" off the floor, the sock and pickup was about 1 1/4". This meant I could have 2 or more gallons before the gas even touches the float.
I reshaped it....
There wasn't much I could do to the float unless I lengthened the arm. I did bend the pickup though.
themechanic
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I'll probably just empty the tank and add a gallon at a time and use the MeterMatch box to calibrate the fuel gauge noting how much gas us in the tank at each increment on the gauge. Like the guy on FABO did as seen in this photo from there.
j-c-c-62
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"How many gallons in a 1/4 tank of gas?"
1/3 of what it takes to fill the tank?
themechanic
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As long as we're just throwing out numbers, I'm guessing, for a 19 gallon tank, it's more than the 6 gallons the A body owner posted jn the photo above.
j-c-c-62
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Unless a tank has consistent equal surface area of the fluid as it fills, the height of the fluid will never be a linear indicator in regard to fuel capacity of the tank. Unless the float/gauge is calibrated for any inconsistency in that fluid area, the gauge will never accurately be representative of the fluid contained, only likely just its height.
A typical A body tank does not meet this requirement.
A typical A body tank does not meet this requirement.
themechanic
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That point was raised in the FABO thread.
Fuel sender comparison. No idea what the OEM sender came out of but by the shape we can imagine the tank shape. The aftermarket sender would be accurate in a square tank. You get it.
j-c-c-62
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And now it has been raised linearly in FBBO, and it applies to any tank
Are you certain, because gauge/wire resistance is determined by wire gauge, spacing, and length, all of which I can only guess at by mere observation.
icetech
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I'm curious how many gallons have to be out of a tank with a spectra unit before it drops below full.. i been paranoid about mine cause it seems to stay on full i went to throw $20 in but it only took 3 gallons and was full.. should the gauge of dropped at missing 3 gals?
Vitamin_A12
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Funny you guys are having this conversation as I’m finishing a multi-decade old project for my wife. It’s a ‘70 Runner with a Spectra premium tank that was absolutely bone dry. Using one of the offshore knock-off senders, I verified the ‘range’ by hooking it up to the Dakota Digital gauges before installing it in the tank. Granted, I did not verify the depth of the float as it sat in the tank. I did verify that when the float swiped through its range of motion that it did go to full. Before I attempted to fire the engine, I dumped 5 gallons of non-oxy in the dry tank and to my amazement, the gauge didn’t move at all…still sitting on empty! Once we get the car aligned and on the road, I’ll see what it takes to make the needle go up and that I’m able to get it to full. I’ll admit, I figured 5 gallons would have made it move at least a needles worth!
18 gallon tank? A 1/4 would be 4 1/2 g. It should be moving towards 3/4 of a tank with 3 gallons gone.
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