ST Project: A hole in the hood part II!
 

One of the goals to my ST replica was to have a hood fill gas tank. The decision has nothing to do with being practical, it just looks cool to me. I will probably end up with paint problems from spilled, dribbled gas but hey that just adds patina. Here it the original post showing how I cut a hole in the hood.

http://forums.pelicanparts.com/porsche-911-technical-forum/128810-st-project-update-hole-hood.html?highlight=project

The last entry says it was time to get out the welder. It has been time for a while. The delay was final alignment of the hood post painting.

The next step was to fab up the filler neck itself. I started with 18G cold-rolled steel that was rolled on a slip roll courtesy of my local roofing/HVAC shop. Total cost was a $10 tip on the guys lunch break. It was fabbed from scrap. 4.5" x 16". I then butt welded the seam and got a round filler neck.

http://forums.pelicanparts.com/uploa...1071701408.jpg

The next step was to align the neck on the tank. I simply closed the hood and set the neck on the tank. Once it was vertical I used black spray paint down the neck to mark its location on top of the tank.

http://forums.pelicanparts.com/uploa...1071701416.jpg
http://forums.pelicanparts.com/uploa...1071701478.jpg

After the marks are made the hole was cut in the tank using my plasma cutter. Next I had to clean up the areas with the grinder and insert the neck. The neck sits about 3/4" below the top of the tank.

http://forums.pelicanparts.com/uploa...1071701500.jpg

After the neck is tacked into place I made sure the hood would close and the neck centered. Next, the filler cap was used. A 100mm filler cap cut from an early 356 gas tank was used. I left about 1.5" of flange on the outside of the cap which will serve as a catch basin and seal support. This will be hidden by the hood. The seal will be an old section of door seal that will be glued in place around the perimiter. I will make a drain by brazing in a small section of tubing to run out the smuggler's box behind the tank.


http://forums.pelicanparts.com/uploa...1071701683.jpg

The filler cap is positioned and tacked into place. Once I was satisfied with the fit I tacked all sides and welded up the neck.
http://forums.pelicanparts.com/uploa...1071701731.jpg

Finished filler is flush with the hood.
http://forums.pelicanparts.com/uploa...1071701685.jpg

The tank still needs some work. Not shown here is the removal of the old filler neck and vent. I welded up a patch. I will now strip the tank and POR. The inside of the tank was spotless. I was tempted to remove all that CIS crap in the bottom. What is all that stuff for anyway? I will send the old filler neck to anyone who answers that question. Shipping not included.

I am in the process of fabbing up the fin for my cap. Its just a section of flat stock (drilled for lightness of course) tacked onto the cap. maybe this weekend I can finish that up.

More assembly is being done on the car. One day I will have it running. The oil tank went to the radiator shop to be boiled out. Should come back nice and clean. Don't want any nasties inside my bearings.

Gotta tell ya... looks great. When you do the seal, post some more pics.

How did you deal with fumes?

i have never seen the inside of a fuel tank. post a pic if you have one. i think the cis "crap" at the bottom of the tank is to isolate the main body of the fuel from the portion of the tank that supplies the engine. the fuel tank is big and deep for a reason. it acts as a heat sink for the gas to minimize vapor lock. the warmer gas that is not burned during combustion goes back to the relatively cooler fuel stored in the tank. the smaller "subtank" inside would minimize sloshing and stuff that would happen for sure inside a big tank. that is my guess. hopefully someone smarter will chime in to let me know.

neat project: where is your tank vent? why didnt you just buy some pipe stock that is the correct guage and diameter? post a finish product photo please.

cliff

Very cool, and DIY, keep us updated.

Awesome work Jamie!

Chuck, you didn't see that bright flash of light in the East? :eek:

Jamie, your progress is amazing. Less than a month until registration opens for the 1st DE of the 2004 season. :D

Oh yeah! forgot to mention a few things. The tank will be vented through the back of the new neck. It will be high enough so that no liquid can escape. The vent will tie in with the existing system which gets sucked into the intake. In reality, I will be changing it a bit. The system is simplified with fumes being trapped by the charcoal filter and then into the intake. No collection tank etc. Just a charcoal filter inline with the intake.

Thanks for making sure I don't pass out driving and thanks for the comments.

Chuck, I will post pics of the seal an drain when they are complete.

Funny Jim, Rollin' on the floor right now. I guess I could get the space program back on target all by myself. DE season is a good goal to shoot for. If not, the targa is a willing candidate.

Cliff, I didn't shoot a pic of the inside. I guess I should have. There is pipe in that size but its all too thick. The thinner stuff is too thin (kitchen stove vets for example). Other material is spriral wound. Nothing fit the correct descriptions so I made my own.

Jamie

Goal? DE's the WHOLE REASON you're building that car! :D :D :D

My wife would be a very rich widow if I tried this project - how the heck did you keep it from blowing up?

BTW, I love the look!

Jim

That rocks! You're giving me twisted ideas...

That's what I wanna know... Did you flush/fill it with Argon or something?

I've welded on VW gas tanks before after nothing more sophisticated than flushing well with water, letting it dry in the sun, then filling with water for the welding.

Lookin' good. You'd better watch out, that one day will turn into today before you know it. Look at dave if he didn't have to rebuild the motor he'd have had that thing from jackstands to cruising in no time.

That is very cool. Sell me a kit!!

The tank has been empty in dry storage for 2.5 years since we parted the donor. I wan't concerned about the fumes. If it had been used prior to that I would have flushed with water and then filled partly with water while welding.

I find it strange that I am giving you ideas Thom. Had I not gone for the S style front bumper I would have fabbed up an air duct for a front cooler like yours. You do some great work.

Very Nice. Keep posting updates and pictures.

Jamie:

One thing I noticed in your pic is the filler cap is flus with the hood. How easy will be removal of the filler cap with the hood down? I would have though raising the cap a 1/2" woudl make it much earier to remove?

Maybe it's just the pic, not sure.

Chuck

Chuck, Its very difficult to open right now. There is no fin on the cap... yet! The cap will be flush with a drilled fin for removal. The fin will stick up about 3/4" and be drilled for lightweight. Its all about the grams. Still have some work to do before its complete. The cap will also be powder coated "chrome" to match the trim on the car. That's another project I have no time for.

Jamie

Welding on a gas tank can be very..... well tricky.
An old racer trick is to drop a bunch of dry ice in there before welding. The dry ice melts into carbon dioxide and displaces enough air to get it below the LEL threashold. It also leaves no residue except for what is condensed out of the atmosphere. I suppose a CO2 fire extinguisher would do the same thing, not sure about that.

DISCLAIMER: in theory this should work just fine and it has been done many times, but anyone trying this method does so at their own risk. I am neither recommending it or condoning this practice.
Anyone attempting this should use an accurate O2 measurement device to ensure all oxygen is displaced.
BTW I don't have anything worth sueing for ;)

Hi Jamie

How long is the filler tube to get the filler flush with the hood?