Re: [AMC-list] d@mned holley carb anyway

[tom jennings <tomj@xxxxxxx>]

My first thought was plastic dissolved, because it only manifested as an
acute problem on the stems of the intake valves. Only there! The carb bowl
did have a "dirty toilet" look where whateveritwas evaporated right at the
top, but whateveritwas stayed solvent, and  new gas would dissolve the old
goo, and so the inside of the carb never got all that dirty.

The fuel:air mist gooped the valve stems really bad. See the photos. The
intake runners and manifold were typically clean. I think the intake valve
was relatively hot (and I now know the fuel charge mixture is cool, around
100 - 150 degrees -- I measured it) and the gasoline droplets evaporated
upon hitting the "hot" valve, leaving the tarry stuff behind. That's totally
consistent with my half-fast chromatography.

Once whateveritwas got all the way into the combustion chamber, it burned
off. Also consistent with plastic (hydrocarbons) dissolved in the fuel. I
don't recall the piston tops being excessively crusty. I did clean 'em off
when I repopped the head.

I think Joe F. said that this car sat for some years up against the side of
someone's house in Northern Calif. Maybe kids put plastic toys or whatever
into the gas tank, and they dissolved. I think it wasn't simply
gas-gone-bad, I think I know enough chemistry to believe that the tarry
stuff is a big molecule, and there should be nothing in gasoline that will
spontaneously generate large enough molecules. I dunno, I could be totally
wrong but gas shouldn't "turn goopy".
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