Fuel cell vents

Geoff · 11-23-05, 01:32 PM

Can any one help with the external dimensions of the fuel cell vents that mount on the cowl by the fuel filler caps (on original GT40's) thay look to be about 25mm dia any help on this would be appreciated as i would like to make some look-alikes for my car.

Thanks Geoff

Bob Childress · 11-23-05, 07:44 PM

Hi Geoff,

If you have any illustrations or information about vents on original cars or good designs from replicas, I for one would also be interested.

The forum has had a lot of safety discussion lately and I think a discussion of this topic would be useful to many with builds in progress.

How are the fuel cells in our cars being vented?
Where are the rollover check valves being placed and the air vent tubes routed?
How and where are the filler-overflow tubes being placed and were do they dump if overfilled?
Should the original cars be copied or is there a safer way to go now days?

Maybe with a little luck, someone will have answers for both of us.

Bob

Geoff · 11-24-05, 01:27 PM

Hi Bob

The vents that I am trying to copy are Fig 3 in the FORD GT40 RESTORATION site www.grandsportcorvette.com/gt/details.htm.
The proper vents/rollover valves will be hidden away somewhere.
On the Tornado you should put some bolts where these vents are so thats why I would like to copy the real ones, I think it will look better than bolts also thats why I only need the external dimensions.

I do hope someone can come up with the dimensions.

Geoff

Bob Childress · 11-26-05, 12:54 AM

Thanks Geoff

I may have a chance to examine an original car over the Xmas holidays and if so I will get detail pictures and the vent dimensions for you.

Bob

Geoff · 11-26-05, 04:36 AM

Bob

If you can do that for me it would be much appreciated and it would get me out into the work shop over Xmas and not looking at the same film as last year and the year before on the TV.

Thanks again

Geoff

Brian Whitworth · 12-16-05, 08:27 PM

Geoff
Re fuel cell vents I saw a picture of the vent on the gt40 restoration web site and decided to make my own by sizing the picture untill it looked about right and went from there I know it is not a very professional way of doing it but I think it has turned out quite well all things considered. they are fully working none return valves and makes the car look a little more like the original. I am in the process of rubbing the body down and getting the shut lines right hence the film of dust all over it.

Cheers

Brian [img]/ubbthreads/images/graemlins/driving.gif[/img]

Brian Whitworth · 12-16-05, 08:33 PM

Another view of the near side fuel vent

Mike Coates · 12-22-05, 12:28 AM

Hi Geoff.

I purchased my vent valves from a company called "Tanks". They are in Clearwater MN, USA Phone 320-558-6882. They are aluminum remote mount and cost $11.0 each. They are about 1 inch in diameter at the vent end and have a 3/8 barb for a rubber tube. I decided to mount the valve part as near to the tank as possible,( probably right on top of the vent tube of the gas tank). In the event of a rollover you do not want a tube full of gas that could catch fire. The valve has a 1/4 NPT male thread on it, so a female NPT to 3/8 hose barb connecor can be connected to it to facilitate routing a vent tube to where ever you want the actual vent to be. The vent is 1 inch diameter and has a 1/4 NPT female thread. A male 1/4 NPT to 3/8 hose barb connector will fit into it. I have not mounted my valves vents yet, as I am still deciding where to put them. I am reluctant to put them near the filler caps, as rain water could get into the vent tube and then into the gas tank.

Mike

chris parker · 12-22-05, 12:44 PM

mike would it be possible to post a picture of them or does the company have a web site to view on line many thanks chris

Mike Coates · 12-22-05, 03:56 PM

Hi Chris.

There is a picture on this web site. It is the remote vent.

http://www.srbymichael.com/manufactu...es-tanks.shtml

Hope this helps. I do not have a digital camera yet so cant forward a photograph. If this does not work for you, let me know , and after Christmas I will get a friend to photograph mine with his digital camera and forward to you. My email address is coates41@telus.net

Mike

Geoff · 12-27-05, 05:40 AM

Brian

Thank you for the information on the vents, they look good and just like the type I would like to make. Can I be realy lazy and ask if you have some drawing and/or dimensions that I can have (why reinvent the wheel I say) If you dont mind me coping you that is.

Geoff

Fred/Belgium · 12-28-05, 05:26 AM

Does someone knows if these can be bought overhere in Europe as they do not send to Europe?
Tx
Fred

chris parker · 12-28-05, 08:11 AM

thanks mike
am i right in thinking that the vents will allow air in and fuel vapour out when the car is upright ie allow the tanks to breathe but in the event of an accident were you roll over the ball bearing closes on the vent to prevent fuel spilling out
fred
my parents have a house in florida and will be over their in a month or so i can get them to bring them back with them and then post off to yourself not sure how quickly you need them thats what i will do
#chris

Fred/Belgium · 12-28-05, 09:26 AM

Chris,
would be fine for me as it is winter time overhere and I am not in a hury.
Do I understand that these vents will breath (when refuelling) but no overspill when hard braking as this is my problem now.
Tx
Fred

Mike Coates · 12-29-05, 04:03 PM

Hi Chris
You are correct, that is exactly how they work.

Bob Childress · 12-29-05, 06:50 PM

I assume all of our cars have the fuel cells located in the side pods. With regard to the air vents, what happens in a side impact if we slide sidways into something or someone crashes into us? Could that cause the fuel cells to be momentarily pressurizes and liquid gas or vapor be sprayed out a dedicated air vent or vented fuel cap?

Is there an inherently safer location for the fuel cells to vent? Would it be better for the vent to exit the car near the ground instead of over the driver? I remember a picture of a GT40 in a front end crash that was posted here last year.

Tim Kay · 12-29-05, 08:25 PM

Here it is, our worst nightmare

Mike Coates · 12-30-05, 04:17 PM

You have raised some interesting points Bob.
I have given this a lot of thought and can’t decide which would be the safest location. The end of the vent needs to be at least as high as the filler cap otherwise if the tank is filled to the top of the filler neck (perhaps not intentionally), gas could exit the vent tube if the end is lower. I noticed that the ball in the rollover vents that I purchased from “Tanks” have a steel ball in them. I would think that the ball would not float if gas comes up the vent tube when the car is in the upright position. In the event of a side impact would the resulting pressure in the tank force the gas up the tube with sufficient pressure to lift the ball and close off the vent tube?
I would think that the actual ball valve would need to be as near to the tank as possible, so that in the event of a rollover you do not have a length of pipe filled with gas that could catch fire. However, the vent tube end should be at least as high as the filler cap.
Is the vent tube location near the filler cap (per the original car) the best location for the vent???
Lots of questions. Lets have some opinions on this for the benefit of safety with our cars.

Bob Childress · 12-31-05, 11:31 AM

Hi Mike and others,

I agree that the roll over check valve should be at the fuel cell. Do any of you know where the vent outlets are on any brand of replicas or kit cars, GT40s or otherwise?

Can the tube from the roll over vent valve be routed up to the height of the filler cap and then do a 180 degree turn to go back down to the bottom of the car to exit?

Hershal Byrd · 01-03-06, 09:47 PM

Hi Bob,
The RF vent tubes come up from the tanks then terminates into the filler necks just below the filler caps. besides the flip up cap there is a screw in rollover cap under it.

Hope this helps.

Hersh [img]/ubbthreads/images/graemlins/smile.gif[/img]