Stock '73 Fuel Tank Expansion

[jacob80]

Hey guys,

 

I am working on putting together a Turbo 240z and have some questions concerning my fuel setup.

 

1. I plan on converting the stock tank to EFI standards via installing an ATL black box. Along with this, we want to expand the volume of the tank by installing ~1" band all the way around. Is this a bad idea? This car is going to be going across the country and capacity is important.

 

2. Right now, we can only fill our gas tank up 1/2 way full but we are not running an expansion tank as we don't have one. Is this vital to vent the gas tank properly, or is there an alternative? The car came without the expansion tank, not sure why.

 

Thanks guys!!

[Tony D]

Gasoline will expand about 10% by volume. If you fuel up and then drive, chances are good you will go the 19-20 miles required to give you space in the tank to then stop and eat and let the diurnal variation cause your fuel to expand.

 

Venting of the tank is crucial to proper pump operation and getting a full tank when at the pump. It needs a high point to bleed the air out of the captive parts of the tank. JDM cars had a 1/4" overboard dump (my 73 for instance...) and that works just fine.

 

See the other comments about using nylon adapters to convert the larger vapor recovery hoses to something smaller, more managable, and cheaper.

 

a 1" band will not give you much capacity. Expect 22-27mpg if the car is running properly and you keep the speed below 80. That's about 3 hours at a stretch driving before you want to think about getting a tank of gas. It's a nice interval to stretch you legs.

 

If you want capacity, cut out the spare tire well, and put in a 77 - 78 gas tank, they are 16 gallons.

 

You CAN fit a 100L (32 Gallon) tank back there. No spare tire. Stock Datsun Part, NLA. Needed a special sender and dashboard gauge anyway. No, you can't use mine. I plan on using it in my Diesel Conversion. At 40mpg conservatively, I'll go 1200 miles between stops. Just about a days drive the way I do it.

 

Forget about that kind of range with a petrol car, you will stop six times and waste 20 minutes a stop each time, so at the end of the day a petrol car will have to drive 2 hours longer per day to keep the same daily pace as I will be able to in my Diesel Z.

 

Yeah, been across the country a couple of times...

Yeah, I use a stopwatch and write stuff down...

[Xnke]

What you can do instead of the ATL black box is take your tank and sump it. I cut the bottom 2" off an old dented up L24 oil pan and carefully ground and fitted it to the bottom of the tank, with the drain oriented to the back of the car. I had previously had the tank boiled out so I didn't fear welding the sump on. The original drain plug is removed, and two more 1" holes were cut in the bottom of the stock tank, and the original feed line was re-bent as to pass through into the new sump, and a new 3/8" pickup line was bent and finangled down into the new sump, about 1/2" off the bottom of the tank. It was then soldered into the original pass-through point in the tank, where the old 3/16" return line was. Make sure that the feed and return are at the back of the tank, and the new fuel sump has three holes near the middle of it, so side to side won't slosh the gas out of the sump, nor will a sudden stop or acceleration.

 

Since you don't have exposed lines hanging from the bottom of the tank, it doesn't appear to be modified to those who don't know the cars well, which can be a plus when dealing with certain laws.