Randall Young wrote:
>
> Jim :
>
> Can't tell you the exact chemical offhand, but Phosphating is a surface
> hardening treatment, somewhat similar to case hardening. It does leave
> the surface looking very rough and dark, but that's just a side effect.
> It will quickly polish up in service.
Strictly speaking, phosphating is not a surface hardening treatment,
since those cause hard precipitates within the metal. Phosphating
precipitates material onto the surface of the metal.
Typical phosphating (with zinc) is to pre-treat metal for painting,
while iron phosphating is normally used as a rust preventative.
Manganese phosphating is the closest to what you describe as a surface
hardening treatment; it provides not surface hardness, but rather, an
anti-wear, anti-friction layer which also holds oil, further reducing
wear. The principal chemicals precipitated onto the surface in this
process are manganese phosphate and iron phosphate.
Traditional literature describes mangano phosphating as a treatment to
minimize "adhesive" wear. It's ideal for parts which scuff against each
other.
If the parts have been mangano phosphated, they should be pre-oiled
before installation. Best practice would be to soak these in warm oil
for a few hours before fitting.
I suspect that for the lifters to perform well, they would have to be
hardened by more traditional methods first, then phosphated to reduce
sliding wear. If the lifter were just phosphated, the lifter face would
wear rather rapidly, since it would be in contact with a much harder
material (the flame-hardened surface of the camshaft). If the lifters
are properly hardened, and phosphated to an adequate thickness, that's a
well-designed aftermarket part.
Cheers.
--
Michael D. Porter
Roswell, NM
[mailto: mporter@zianet.com]
`70 GT6+ (being refurbished, slowly)
`71 GT6 Mk. III (organ donor)
`72 GT6 Mk. III (daily driver)
`64 TR4 (awaiting intensive care)
`80 TR7 (3.8 liter Buick-powered)
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