Tom,
Hydrogen embrittlement is a well known phenomena resulting from
operations like the acid in an chrome electroplate penetrating into a
wire wheel spoke and degrading it's tensile strength. Many 50's era
chrome shops were turning out chromed wheels that the factory had
painted. It resulted in quickly broken spokes. The lesson was learned
to BAKE the spokes in an oven to remove the hydrogen.
Commercial wire wheel manufacturers mostly used stainless for
performance wires. The rims were fine, as they were not stressed as
highly as the spokes.
This lesson was learned in the 50's around here, and any chrome shop the
EPA still let's operate know this.
Aluminum will not absorb hydrogen and become brittle, the acid etch is
neutralized, in any event, to prevent any left-over fluid pockets from
continuing to eat away in cavities.
I would be a LOT more concerned about electrolysis, wherein the aluminum
is dissolved into the coolant passages by electrolysis. This is caused
by metals that are on the other side of the electromotive table, and
iron is one of them.
A special additive is in the anti-freeze that inhibits this, and has
nothing to do with freezing. It needs replacing about every year by
changing antifreeze or adding it from a separate small bottle.
A better solution is to stick a grounded rod of magnesium into the
coolant system. This is common practice on salt water boat engines, and
J.C. Whitney sells a stack of magnesium disks for this job. They
dissolve instead of the aluminum, being more reactive on the EMF table,
and don't need replacement as often. Just check them every so often to
make sure they are still there.
Boat shops have zinc plugs and rods for boats, but they don't want to
fit into my overflow tank. Next time I have the radiator out, I'll add
a boss on an end tank and use an external screw one boat version.
There is a CHEAP alternative. Those chromed thermostat housings are
made of chrome plated zinc. They will erode, inside, and protect your
expensive F4B manifold. However they were very ignorant is using such a
soft metal and a poorly designed O-ring seal. The ears bend under the
bolt tension, and the O-ring leaks when you have tightened it to a fully
bent position. If you don't mind checking and replacing them, it's a
cheap solution for the manifold water passages.
Forget about the intake ports, the gain is minimal unless you have flow
bench people go through your entire system, matching carb size, valve
sizes, cam profiles, SHAPES of the intake runners, and grinding away at
the protruding valve guide bosses to remove the excess blockage, yet
leave enough for strength.
Did anyone tell you speed is spelled $$$$Peeed! :-)
Steve
Tom Witt wrote:
>-----
> So, to get back to my original premise, 'will the acid process make the
>cast material more likely to crack due to embrittlement?' thanks for any
>help.
>Tom Witt
>
>
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Steve Laifman
Editor
http://www.TigersUnited.com
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