Continuing the ongoing saga of the snake fuel tank there's not a lot new
to report. I've cleaned all of the undercoating from the outside. I
used paint and epoxy stripper which got me to thinking that this stuff
would work really well to remove old contact cement; at least from bare
metal. I wouldn't try it on Fiberglass for obvious reasons. I've
flushed the inside with hot solutions of Simple Green and TSP, followed
by cold and hot water rinses, followed, finally, by an alcohol rinse to
remove as much moisture as possible. In spite of this, I can still
stick my finger into the outlet hole at the bottom of the tank and feel
grime inside. Time for professional help, I suspect. I got a
suggestion from one person on the list to check auto restoration shops
in addition to radiator shops. I think this is a good suggestions since
I would guess that a professional restorer is more likely to have
encounter an oddball tank like mine. At least, I hope that's the case.
I've pretty well confirmed that the entire outside of the tank is coated
(tinned) with solder. All of the seams are soldered, as well. I can't
tell for sure if this is the case inside of the tank, but I suspect it
is. Hmmm, guess that means I'll always have leaded gas in the tank.
This seems unusual to me and could be a problem when I have the tank
de-rusted and coated.
Interestingly, in a letter published in the current ACOC newsletter
there's a brief reference to the outlet fitting size of Ace and Cobra
fuel tanks. The writer claims the size is 3/8" BSP, but I think this is
either a misprint or a mistake on the writer's part. I suspect the
correct size is 3/4" BSP.
In the mean time I've gotten myself side tracked trying to learn the art
of aluminum auto body repair. All I've learned so far is that I'm
incredibly inept at it. I'm proceeding at a very slow pace along the
shallowist of learning curves. I don't think I've done any permanent
damage since things don't appear to be worse than when I started; but
I'm not sure they're any better, either.
The reason for this side excursion is that I managed to do some body
damage around the fuel filler neck when I removed the tank. I also want
to take care of a couple of other jobs while I have access to the space
where the tank was.
One skill (of many) I haven't mastered yet is how to use a pick hammer
to raise low spots from inside without being able to see where I
hammering. Actually, I'm not sure I could do this even if I could see
what I was whacking away at. This is something that takes a bit of
practice for someone as klutzy as myself. So that I don't end up with a
bunch of unwanted lumps, I've tried coming up with schemes to make this
operation a little more precise. My first approach was to locate low
spots on the outside (visible) surface from some reference point, then
carefully measuring from the same reference to the spot on the bottom
side. Instead of trying to raise the spot with a pick hammer, I used
light hammer taps on a socket extension or a small diameter bolt with
the end rounded. This seemed to worked pretty well but got tedious very
quickly. My current approach is to use a modified C-clamp. With this
setup I can accurately locate the business end of the clamp from the
top. The shortcoming of this method is that it only works for a limited
distance from edges that the clamp will fit over.
I've also gotten some metal working tips from a message I posted to
rec.crafts.metalworking. The consensus seems to be that the best
sources of information on aluminum sheet forming are books on aircraft
construction, especially for homebuilders. Book suggestions, anyone?
Aluminum work hardens very quickly, but, fortunately, can be annealed to
its original softness and worked some more. This can go on almost
indefinitely. What's difficult is shrinking stretched metal. Possibly
it can be done with heat followed by little hammer and dolly work
similar to the technique used to shrink sheet steel but I haven't come
across a description of how to do this yet. I'm not sure I have the
annealing quite right yet either. The techniques is to soot up the
surface with a gas rich torch then to readjust the flame and heat the
metal until the soot burns off. One book says to quench with water
right away and another says to wait until the metal cool to 200 degrees
or less before quenching. At this point I haven't been able to bring
myself to heat the metal to the point where the soot is burned off. I
have this mental image of a big blob of aluminum suddenly collapsing and
leaving a big hole in my snake.
When I get done with this (assuming I don't give up and let someone who
knows what the hell they're doing take over) I'll write up all the tips
and techniques I've picked up. I'm thinking about calling it Aluminum
Auto Body Repair for the Hopelessly inept.
Roland Dudley
cobra@hpcdcsn.cdc.hp.com
CSX2282
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