Sump capacity of gas tanks on Formal NYB’s

[73 T&C]

Mystery question of the day…

Recently, I had put in 8 gallons of gas in two parts while installing and setting up my Holley Sniper on my 1978 NYB. Tank was bone dry due to new in-tank pump and sender install.

Replacement sender was a match for original as to float movement, location and orientation on install.

Assuming we burned half of that 8 gallons while working on the system and sorting other issues, it still showed empty throughout.

So…. Does anyone out there know the actual sump capacity (dead gas at the bottom of the tank) before sender starts showing some gas in the tank?

It’s an academic question, I know, but still good to know. I’m thinking it’s a lot at 4 to 5 gallons.

 

[CBODY67]

Did you re-ground the sender to the body-section of the fuel line after the install?

Just checking,
CBODY67

 

[73 T&C]

Did you re-ground the sender to the body-section of the fuel line after the install?

Just checking,
CBODY67

Yes it works fine. After dropping in 15 gallons the gauge shows 3/4 full.

 

[mopardug]

IIRC, the Caddy's of the day had five gallons left when the fuel light came on.

 

[commando1]

My NYB took over 20 gallons when low fuel indicator light came on at 1/4 of a tank.

 

[thethee]

Okay there's too many variables to make a decent calculation so I'll attempt to just give a ballpark figure. I believe the tanks dimensions are roughly 28" by 32". Assuming it takes an inch of fuel before the sending unit starts moving that's just under 4 gallons. That seems excessive so it'll probably be less than that.

 

[70bigblockdodge]

With as big and flat as that tank is I don't think 4 gallons is unreasonable.

 

[73 T&C]

I’m thinking the 4 Gallons of dead gas at the bottom is about right.

On Saturday I filled it to make sure I had no leaks … no leaks.

The shop put 3-1/2 gallons from bone dry. After about a week of running it without moving I figure they burned about a gallon. (Just a guess). I saw that we flushed the fuel line with about a quart of gas. So the tank maybe had two gallons in it when I added the 5 gallons in it last weekend. But light was still on and needle was right at the empty line. So we had 6 plus gallons in it when I started driving it. But at that level it would starve the pump and stall the engine. 15 gallons got us to 3/4 tank. Another ten this weekend had the gauge showing full.

 

[73 T&C]

Okay there's too many variables to make a decent calculation so I'll attempt to just give a ballpark figure. I believe the tanks dimensions are roughly 28" by 32". Assuming it takes an inch of fuel before the sending unit starts moving that's just under 4 gallons. That seems excessive so it'll probably be less than that.

Sounds about right.

But I think that we set the pickup at just under two inches. The tank also sits at a bit of an angle (slopes up toward the back). This was one of the reasons we set the pick up a bit higher. We wanted some sump in the tank. May bring that down some after I start using it a bit.

Assuming the tank is 26 gallons this gives me about 22-23 gallons usable gas with a last gallon of iffy gas before she starts stalling out. Red light will mean I’m out of reliable gas.