ST- Replica Project - Any ideas on how to build a through-hood gas tank filler

katigbr · 08-18-2002, 06:00 PM

BBSers,
After a year of tracking "Gretchen", I've decided to go for a more agressive look and wider 17" tires. The car has been fabulous on the track and has been a blast to drive. I decided to perform an ST replica conversion on my unfinished RS-replica (unpainted). This time I'll finish the painting (no 3.6 swap to do this winter).

I'm working with Hank at GT-racing on the ST flares front and back, along with 911R F/G doors for some added weight savings.

One of the things that I've always liked was the hood mounted fuel filler location. Does anybody have any pics of the tank that is used with the through-hood filler? Are these still available? Any suggestions on how to build, source or adapt my existing tank?

What is the correct hole placement location?

Here's a pic of the ST that triggered this project.

Thanks in advance.

Regards,
Rick

KevinP73 · 08-18-2002, 06:58 PM

I modified an OEM tank to accomplish the thru the hood filler. I got the 1/4 twist cap and socket from Pegasus Racing. A short piece of seamless tubing(3" if memory serves me ) the correct length raises the filler cap flush with the hood surface. Very carefully cut a whole in the tank leaving enough material to form a flange that will act as a reciever for the 3" tubing so a proper weld joint can be made. I cut the original filler neck and welded a block plug over the opening. The tank was then cleaned inside and out and resealed. Has been in service for several years with out any problems.

KevinP73 · 08-18-2002, 07:07 PM

Here's one with a little higher tech look to it. This one is on top of a fuel cell(much easier to do).

katigbr · 08-26-2002, 04:50 PM

KevinP73,
Thanks for the reply. I'll check out Pegasus for the cap and socket. It seems fairly straightforward. Did you try looking for the original gas cap style. I recall seeing one with several holes drilled through a fin attached to the cap. Your suggestion sounds like a workable (affordable) solution. Apologies for the delay in thanking you.

Regards,
Rick

Chuck Moreland · 08-26-2002, 06:01 PM

Kevin

I like that setup! I've been looking at options for doing this on my '73 project.

Another less elegant but simpler solution is to shorten the factory filler, then bring it over using a flex hose to a rigidly mount center fill. The factory used flex hoses so I think it would be fine from a safety perspective. But not a slick as Kevin's solution.

kstar · 08-26-2002, 06:16 PM

Great thread!

I have been considering the hood/fill location and it is encouraging to see that it can be done with a standard tank - thanks Kevin.

I would like one of those turned metal, drilled/finned gas caps though but may not want to pay the price of an R wheel.

Somewhat on topic, how does one get the same look with the '72 oil filler location, i.e. an exposed oil filler cap instead of the oil door?

Thanks and best regards,

Kurt

HawgRyder · HawgRyder's Garage

An old trick for welding on gas tanks...fill it with carbon monoxide!
In other words...run a hose from the family slug-mobile into the hole of the tank...let the family car idle for a while...and then go to work.
I have welded patches on tanks that were only emptied not flushed.
Even if you flush the tank, you can still get a backfire or two.
Also...to re-enforce the opening for the new spigot (fill pipe) I would weld a patch of bigger proportions in the correct area before cutting the hole...then when you cut into the tank you will have 2 layers of steel to weld to.
Bob

KevinP73 · 08-26-2002, 07:02 PM

I should mention that the tank I started with had sat empty for at least a year and didn't even have a hint of fuel (or vapor) left in it. I wouldn't even suggest that someone start cutting or welding on a tank that has been recently drained and not thoroughly flushed and cleaned. Washing a tank with water is not good enough, they have to be cleaned with an appropriate solvent.

Chuck Moreland · 08-26-2002, 07:41 PM

What qualifies as an "appropriate solvent"?

KevinP73 · 08-26-2002, 08:12 PM

You should ask someone with a bit more experience with solvents or gasoline. I'm just sure soap and water isn't enough.

Efrain68912 · 08-26-2002, 08:49 PM

I've heard some stuff called Muratic Acid or something by similar name is just as effective as having the tank boiled out.

Typical Fish · Typical Fish's Garage

Out of curiousity (and obvious ignorance)...

What is the advantage of having the filler in the center of the hood as opposed to the top of the fender? I would think it would make it more of a pain in the a**.

Enlightenment, please. I am sure it makes sense somehow, I just can't figure it out.

CamB · CamB's Garage

That's easy.

When you pull into the pits after racing for an hour, and the 100 litre tank is empty, those centre fill gas tanks can take a much higher rate of flow of gas from your pit crew.

It means you are back out on the track quicker, ahead of the competition.

Me? I like it cause it looks like a period race car

A Quiet Boom · A Quiet Boom's Garage

Quote:

Originally posted by Chuck Moreland
What qualifies as an "appropriate solvent"?

Toulene would be a good start followed by splashing with MEK, basically you need to solublize any remaining gasoline and wash it out of the tank with the solvent, but the solvent must also be removed so a "faster" (evaporation rate) solvent is then used to remove the traces of the first solvent. Follow this with water just to be safe. Personally I think good old water soluble degreaser and water will do the trick provided you slosh it around enough. Soap and degreasers emulsify organic solvents allowing them to be carried away with the water. I've scrapped a few cars in the past and the local yard won't take them with the tank intact, I just fill them with soap and water and cut them open with a torch, I welded a leaky fuel tank on my truck in the same way.

Chuck Moreland · 08-27-2002, 07:32 AM

I suppose you could also fill the tank 90% with water, leaving the section to be welded at the very top. That way the water wouldn't wick away too much heat and the amount of potential vapor is way down. Not unlike the suggestion above to fill with CO, but I'd feel safer since I can actually see the water.

TRE Cup · TRE Cup's Garage

www.autofarm.co.uk can help you with getting the same fuel cell as installed in the ST pictured. It is an exact visual replica of the ST tank with fia style race bladder and foam(They prepped the "psychedelique" ST for the Tour Auto 2001, and we came along to help support it- THAT was a lot of fun!)
The cell is manufactured to their specs by Fuel Safe UK. The cell is not on their website, but if you contact them, Josh will get you a quote

jwetering · jwetering's Garage

Back in the lab, we would use acetone to remove water from newly washed glassware...this was done so we could oven dry the glassware more quickly.

I mention this because you could do the same in reverse....ie flush the tank with a solvent that is miscible with both gasoline and water. The cheapest and easiest is methanol aka methyl hydrate aka gas line antifreeze.

After a good alcohol wash, the residual methanol, which will contain traces of gasoline, can then be flushed out with water.....lots of water.

bon chance!

katigbr · 08-27-2002, 03:10 PM

Thanks all for the advice and the lead on the Autofarm tank. It sounds great but may be too expensive for my needs.

I don't know what is scarier, the potential explosion welding on a gas tank or dealing with the nasty solvents used to prep the tank for welding.

I did find some bolt on fuel cell filler necks and caps at Jeg's that might work if I have enough space on the tank to screw them onto. They come with gaskets so they should seal okay. I'll use a hole saw to cut the hole cleanly and fill the tank with water before I cut.

They are available in 4" and 8" lengths. Based on KevinP73's post, the 4" should be okay. I can cut and reweld to the right length. The only thing left is to make the filler cap look "right"

Thanks again,
Rick

Chuck Moreland · 08-27-2002, 03:43 PM

Are you going to use self tapping screws? I'd be a little worried about getting a secure enough connection with those.

I don't see a way to get a nut behind that.

82SC · 08-27-2002, 04:39 PM

could you drill the main hole...

drill the surrounding holes...

then secure nuts on the underside via the big hole...then screw the filler neck on...???

I've also seen those clips the slid on with a large hole on one side and a metal hole on the other side to secure the screw...(for securing speakers to door panels)