[Mgs] Unleaded fuel and Cylinder Head

[Paul Hunt]

This is it.  Research claimed to be from BMW some years ago stated that if an
engine had done at least 40k on leaded and hadn't had the valves replaced or
the seats recut then there would be enough lead leached into the surfaces to
protect them for the rest of their service life (whatever that is).  Tests in
the UK have shown that it is only when the engine is run at full throttle or
very nearly so for long periods do you get any recession anyway.  I choose to
use an additive and haven't had to open up the clearances since the UK lost
leaded 10 years ago.  I don't do a huge number of miles each year but what I
do are done 'enthusiastically'.  It is totally uneconomic to have a head
converted purely to avoid buying an additive, an MGOC study in 2002 reckoned
70,000 miles if you did the work yourself, double that if you paid someone
else.  That was at UK prices, from what I have seen of the costs of parts and
labour in America it would probably be much more.  Of course, if the head
needs replacing anyway due to cracking or warping and you are buying from a
reputable source it makes sense to fit one that has been converted, unless you
choose to buy an unknown quantity from a scrapyard or somesuch.  Even then the
MGOC study said that hardened seats and valves offer no more protection
against recession than the best additive, it just saves you buying and adding
it.

PaulH.
  ----- Original Message -----


  My '67 MGB has 330K miles on it and I've never made any modifications to
the
  head for unleaded fuel.  I bought the car in '79 with 100K miles on it and
  have rebuilt 3 engines for it, the first when I first got the car.  No
removed
  head has had excessive valve seat wear and I don't use any additives.