Fuel Tank crossover / equalizer

Big-Foot · Dec 30, 2007

Curious if anyone has successfully implemented a crossover system to keep the fuel load equalized between the two tanks on a GT40..

I was thinking (dangerous - I know) that it would be a PITB to have to hold the fuel filling hose at the service station over the top of the car to fill the tank on the opposite side. Also curious how it was done on some of the Gulf cars I've seen with only a single fuel filler..

Thanks guys...

Jim Sheren · Dec 30, 2007

<TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on"><TBODY><TR height="100%" UNSELECTABLE="on" width="100%"><TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off">Randy,

Could you weld threaded bungs into each tank close to where the tanks are welded to the fire wall behind the seats?? I know this sounds scary, but you could use a re-enforced type rubber hose, kind of like hydraulic hose to connect the two tanks, then take 1/8" wall aluminum tubing and cut a 1/4 of it away and then build a shield around it. So the line would be down in the bottom coner behind your butt, then the shield looks like a fillet going around it. I would assume it could go through the tunnel for the radiator cooling tubes and not take up too much space?

Maybe this is just crazy. Without looking at it and seeing the packaging it's hard to say.

I know Fran is probably cringing, Sorry in advance Fran

Maybe Fran could offer this; wink, wink

Or maybe not.

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Jim C · Dec 30, 2007

Yes

all I have done and others have done the same. A pipe 3/4 to 1" between tanks.
Mine runs from the rear of the tanks across the bottom of the rear bulk head(firewall)at floor level.

Im still running 2 filler caps but have gone to 1 fuel sender.

Jim

jac mac · Dec 30, 2007

I'm planning on running a tube or hose thru an alloy tube under the front of the seat area. The lower part of the seat being a fixed metal piece as per the originals & to be welded into the structure. I feel this is about the safest area in the car and dont like the idea of tubes/hoses in the proximity of the front damper etc where if damage was to occur it wont be easily spotted.

Russ Noble · Dec 30, 2007

I'm planning on keeping mine seperate. Twin fillers don't seem to be a problem. Lots of Jags use them. I know the XJ's had twin fillers and I'm sure from years gone by that my old Mk VIII 3.4 MOD had them also.

If you want it to equalise quickly while you're filling I think you'll need more than a 1'' crossover. I think I read somewhere that the Gulf cars had a 2'' or 2 and a half inch crossover.

Cheers,

delaneyp · Dec 30, 2007

Randy, for what its worth, I have separate tanks/fillers & a change-over valve - never had a problem filling up 2 tanks as the car is so low that the petrol station hose is easily taken around the front from one side to the other (also provides a talking point for the gawkers, etc) !!

If you join the 2 tanks & want to fill from one side, you will need at least a 1" crossover pipe (as Russ mentioned). IMHO, the less fuel piping (and the smaller it is) is a safer prospect - the thought of a 1" or 2" crossover pipe at the bottom of the tanks letting go is not a nice thought !

I have a separate fuel sender & gauge for each tank - given the long / shallow tanks, these are rudimentary at best : you get a bit of an idea of what's there on the level, but most of the time they act as inclinometers ! If they read full, you are going up / if they read empty, you are going down !!

Kind Regards,

Peter D.

IanAnderson · Dec 30, 2007

With the big cross over pipe don't forget to run an air bleed pipe too or when you fill the tanks the one without the filler is going to not fill to well with a bib "air bubble" above the fue;l level

Also suggestion if you go this route make the working cap opposite to your driving seat - it will save problems when you pull up to the pump and cannot open your door as you are too close to the pump (yes I did it once)

Ian

Big-Foot · Dec 30, 2007

Great responses guys.... Thanks for your input! Yes I have thought of running the crossover pipe through the interior just aft of the seats but my issue is in how to get the pipe through the tunnel without taking up too much space. I had thought of using rectangular tubing that would lay flat - but I would need to weld it in place (not the end of the world) to maintain the integrity of the tub.. So my next thoughts were to actually place the crossover in the engine bay yet protect it well from debris... Not certain just how yet... Still examining alternatives.. I'll try to get a picture of the bay uploaded here later..

IanAnderson said:
With the big cross over pipe don't forget to run an air bleed pipe too or when you fill the tanks the one without the filler is going to not fill to well with a bib "air bubble" above the fue;l level
Ian

Good point - There are breather tubes right next to the fill tubes on the RCR.

IanAnderson said:
Also suggestion if you go this route make the working cap opposite to your driving seat - it will save problems when you pull up to the pump and cannot open your door as you are too close to the pump (yes I did it once)

Ian

Ian - you hit the nail on the head directly... This was the first thing that triggered my entire train of thought on the subject...

dlindemann · Dec 30, 2007

Hi Randy -

Lotus Esprits have dual tanks and cross-over pipes. My S1 has a very small diameter cross-over of about 5/16" and it is too small to be effective - I still have to fill both tanks. The cross-over consists of a steel tube running across the engine bay with fuel hose connections to each tank. Later Esprits utilized a larger diameter cross-over pipe. I'm not sure of the exact size but it is an inch or less in diameter. This allows filling from one side with venting provided by removing the filler cap on the opposite side. Not sure I'd want to run a fuel line through the interior of the car - just my $.02.

Dave L

Andy Sheldon · Dec 30, 2007

Big Foot

We have linked tanks to use a single filler on a few cars fully built for customers.

We used 1 1/2" diameter link pipe. It needs to be large enough so that it can flow into the second tank as quick as the first is filled by the petrol pump at the filler station.

Thanks

Andy

wbmusarra · Dec 30, 2007

When laying out my concerns for the fuel lines, I made the decision to use one set of pumps. The cost of the AN fittings and the pumps were getting rather expensive. Since I have Fuel injection, my concerns centered around the flow of the fuel. What I came up with is very simple. The uptake to the pumps is from rear of the passenger side(LHD). Once the circuit for the fuel leaves the injectors, it flows back to the surge tank. The overflow then is routed to the drivers side tank. The two tanks will be connected via AN lines(size not determined yet). The pan of the DRBs is corregated and the line will be secured to that on the outside. I have a fear of leaking fuel in the cabin. The fill pipes are enough to worry about. The line connecting the two tanks will have a flapper valve(no resistance to flow), with the flow directed to the passenger side. Both tanks will be vented and rollover protected. The fuel guage will use a non moving sender, so I will have an accurate measure of reserve.

Bill

Cobraownr · Dec 30, 2007

Big-Foot said:
Curious if anyone has successfully implemented a crossover system to keep the fuel load equalized between the two tanks on a GT40..

I was thinking (dangerous - I know) that it would be a PITB to have to hold the fuel filling hose at the service station over the top of the car to fill the tank on the opposite side. Also curious how it was done on some of the Gulf cars I've seen with only a single fuel filler..

Thanks guys...

A number of original Mk I GT40s had a fuel crossover pipe and just one filler cap. Six independent Mk Is (including my P1040) that were prepared by FAV for 1966 Le Mans had this feature. The crossover pipe in my car runs from right to left just in front of the seats. However, this may not be the original spec, as I know my tanks are not original. A few of the later Mk Is also had fuel crossovers, and some (and maybe all) Mk IIs.

prre · Dec 30, 2007

Bill what type of non moving sender unit are you going to use?

wbmusarra · Dec 31, 2007

Paul,
Racer Parts Wholesale has the Fuel Safe one. Not sure if that is the one I have, but it works the same. You have to supply the Ohms, and they will ship it. I have a Stewart Warner gauge and it works very nicely. My car isn't at home right now or I would send some pics. It should be here in the next day or two. Exhaust is being fabed at present.The unit can be shortened to 3 1/2" if need be. Mine has the same features as theirs I believe. It should have a low level sensor that is adjustable and can be wired to turn on a warning light. If it doesn't then mine is different and I will send you the info when the car gets home. The full point is adjustable as well. Not exactly cheap, but it is nice to have a reminder that the tank is getting low. If this isn't the page just scroll down near the end of the catalog.
http://www.racerpartswholesale.com/downloads/Fuel Safe Catalog.pdf

prre · Dec 31, 2007

Thnaks Bill for the info I will check it out.

Regards

wbmusarra · Jan 1, 2008

Pegasus Auto Racing has the full description and is a few bucks cheaper.

Pegasus - Fuel Level Gauge for Fuel Cells, 0-90 Ohm

They also have the 240-33 Ohm unit as well.

Bill

v8goat · Jan 10, 2008

Hi Bill,
I have always run the injector return back to the main tank, as I had heard that if it runs back to the surge tank that it can go round and round from surge tank to injector rail back to surge tank to injector rail etc, heating up a little each time it travels the injector rail (from heat of engine).

IanAnderson · Jan 10, 2008

Dee

A lot of discussion on this in the past
Go downhill on 1/2 tanks with the return to the main tank and you are likely to pump all the fuel out the surge / swirl post very quickly

Even a Facit red top will pump about 3 litres per minute - how big is your swirl tank to avoid sucking air?

Ian

v8goat · Jan 12, 2008

Ian,
hmm, I had not thought about that, I can see now that the long narrow tanks on a gt40 can be an issue, If someone was to run a pump in each tank, a pickup in the rear of one and the front of the other would work, provided there is a fuel crossover pipe, but I guess the point of the fuel crossover pipe is so that you only need 1 pump... catch 22 I guess.
Surge tanks that I have made in the past have been around 2-3 litres.
Dee

576103 · Jan 14, 2008

Apropos of this thread, here is the Ford factory drawing of the original Mk 1 fuel system:

Note the fact that there are two fillers and two fuel senders, and the fuel pickups are in distinctly different locations. It appears there was no crossover, but instead the fuel was drawn from both tanks more or less equally, with a manual valve which could select one or the other tank (or both).

I do think that a crossover system would be a very good idea, however.

Fuel Tank crossover / equalizer

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