Yes alloy head.
Some years ago I bought a Matchless cheap with a blown head gasket,
the washers were mild steel and chewed up and had bowed/sunk. I
tracked some down from an old motorcycle shop, they were thicker and
the top edge shamfered slightly, I remember the guy telling me they
were expensive as they were hardened. He had them made for a vintage
machine he was rebuilding.
I had thought of using some 316 stainless, but was wondering just what
spec is normally used for these washers.
Have just bought a Sunbeam to tinker with, want to replace some of the
hard to get nuts with stainless, in no hurry to get it all done, but
when the head comes off was planning to use new washers and nuts, to
tidy up all the chewed up nuts. At present the washers appear
different diameters and thicknesses.
I could probably buy these in, but interested to know how hard the
washers need to be.
For most purposes, washers should be soft. They're there to spread the load
from the nut and to protect the face of the part from being buggered up by the
nut. Spreading the load needs soft, protection needs new washers when they get
If the washers dish on the first use, make them thicker. If they dish on
subsequent use, make new ones...
Hard washers are only really called for when they are working against machined
surfaces or acting as spacers (swinging arm caps would be a good case).
EN8 or EN16 will be pretty much the same as mild steel in un-hardened form. I
would avoid leaded EN1A purely because it is far more susceptible to corrosion
than unleaded varieties.
Oil bluing won't do a lot of good, but won't do any harm at all.
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.