c3 gas tank

[Denny J.]

Got the gas tank down and removed the new and going to put in the old one.But first 4 sets of #s pencil and yellow crayon white chaulk does somone keep the # with photos
G 14-2 on back wall tank hole top 6301 10 on back of plate 5252 than by the pass exhaust has a paper tag automtive products division north american packwell reinforced plastics operation 13-72
what els should I look for to help you out.Denny72

[Chuck S.]

Re: c3 gas tank

Denny, the marks on the rear compartment wall are typically a body shop sequence number that appears other places on the car. On earlier cars, this sequence number is usually a three digit number. Your marks, G14-2, do not make sense in this context, but maybe the marking methods changed for 72.

The hand written number on the underside of the deck has been discussed here, and I believe it was determined to be the fabricator's build date. Hand written dates on fiberglass panels are common, and are nothing fancy, i.e. a simple month/day/shift. As a date, this format would make the date June 30 (1972), first shift. I have no idea what the "10" means.

The hand written number on the tail light panel is typically a date, and in your case, it would be May 25 (1972), second shift.

The embedded North American Rockwell tag is a date tag for that particular fiberglass panel, thirteenth week of 1972. Many of the fiberglass panels will have these tags, but they are usually positioned so as to be hidden inside the body (like this one) or covered by blackout and undercoating.

By providing your car's build date, we can probably make more definitive statements about the marks...if they are dates, they will precede the car's build date, and make sense in the context of the build date. If the marks ARE dates, then I'm thinking your build date is in July.

[Denny J.]

Re: c3 gas tank

Yes sir July 19
So there is no other info for you guys,
While the tank is down.
Go ahead button it up. Denny72

[Chuck S.]

Re: c3 gas tank

Sometimes, on the deck underside back toward the spoiler you will see a paint stamped circle with a dot in the center...I have no idea what this mark means.

I seem to remember that original fuel tanks have been seen with some blue stamped marks on them; check your tank's top surface carefully. I have never personally seen such marks...my car didn't have the original tank or tank sticker. I was fortunate enough to later locate and recover maintenance receipts which included the original owner's purchase of a replacement tank from Mr. Goodwrench.

[Chuck S.]

Blue Stamp On Gas Tank...

With stimulation, the brain cells are rousing just a little. I believe the blue markings were trademarks from the galvanized sheet steel supplier; my memory seems to think Armco.

The galvanized sheet was stamped to shape and machine welded to assemble the shell. The weld resembled the original roll type welds made on Delco shock absorbers. The shell assembly weld rusts easily...that's the obvious tell that the tank shell was stamped from galvanized steel, inside and out, and then welded together.

[John H.]

Re: Blue Stamp On Gas Tank...

The tanks were fabricated from terne-plated steel (terne-plating is lead-based); galvanized is a hot-dip process (zinc-based). The serrated copper rollers that did the seam-weld between the two halves burned off a fair amount of the terne-plating, and rust on the seam was common as a result.

[Chuck S.]

Re: Blue Stamp On Gas Tank...

Interesting...I assumed it was galvanized because I observed a crystalline structure in the coating.

Wikipedia says terne, or alternately terneplate, is an alloy of lead with 15% tin. Apparently, it can also be used in a hot-dip process..."This is the minimum tin content required to obtain an adherent coating on hot-dipped iron sheet."

Further, "Terne is used to coat sheet steel to inhibit corrosion. It is the one of the cheapest alloys suitable for this, and the tin content is kept at a minimum for precisely this purpose, to minimise the cost."

Cool...I learn something new every day I hang around you guys.

[Terry M.]

Zinc coating expanded

Galvanized metal can be hot-dipped -- the metal is submerged in a zinc-based liquid -- this process leaves a unique faceted surface finish. Garden equipment, or outdoor metal posts, or road barriers are often hot-dipped. This zinc coating is quite thick, and is suitable for extended outdoor exposure.

Galvanized metal can be electroplated -- the zinc-rich surface is transferred electrically from a sacrificial electrode (or is it anode, I have forgotten which it is). this is a plating process like that used for copper or chrome decorative plating. Unless the surface is polished it will be a dull light gray, almost white, as it comes from the plating bath. This zinc coating is thinner than the hot-dip coating, and as a result will last less time at the same exposure levels.

Most zinc coatings on cars (relay covers, brake dust shields, and the like) are electroplated.

[Jack H.]

In electro-plating...

the donor metal connects to the positive battery cable and is termed the 'anode' while the target part connect to the negative side and is called the cathode.

[Terry M.]

Re: In electro-plating...

I knew you would know the answer. I was too lazy to look it up, and it was not significant tothe point I was making.

BTW: Off the board I was reminded that the classic example of hot-dipped galvanizing is Wheeling galvanized garbage cans.

[Jack H.]

Yep!

Anode/cathode + oxidation/reduction are those definitions we typically learn just long enough to pass chemistry tests in college! I too, have to crack a book to remember what I once learned, Terry!!!

[Denny J.]

Re: Yep!

Is this why they are plastic now.

[John H.]

Re: Yep!

Denny -

The production plastic fuel tanks are more costly than the welded steel tanks (due to the non-permeable barrier material molded simultaneously on the inside to pass the evaporative emission requirements), but they can be molded in unusual shapes to accommodate vehicle packaging needs that can't be achieved with steel tanks.