<VV> Head milling, was: PG Turbos??

[craig nicol]

<snip>
Frank said: People around here are cutting the gasket surface down to the
point where no step exists between the gasket surface and the major flat
area of the combustion chamber. The reports are LESS pinging!
Frank DuVal
ps, also have to take a similar amount off the head surface so the jug
will slide all the way in to the new surface.

Mark said: FYI, tried that on one of my cars. STILL can't use regular gas
without encountering MUCHOS GRANDIS dieseling upon shutdown. So while you
may reduce or eliminate detonation, the "modern" (what passes for) gas will
still give you grief. So don't do it with the idea of going to a lower
octane-rated grade of gas. My conclusion is that it is of questionable
value, given the "gas" that's
available today.
<unsnip>

If you just mill the head (and deck), the compression will be raised
dramatically and it's likely that detonation will continue for any given
fuel.  For this mod to be complete, you either have to enlarge the
combustion chambers to bring the compression ratio back into range or have
the pistons milled (in the area below the chamber only) for the same effect.
The whole point of the mod is to keep the compression ratio in spec while
increasing the turbulence and making the combustion chamber more compact
(which reduces the need for initial advance).

Current vehicles can run 10:1 or more using these principles.  Turbulence is
so beneficial that four valve engines sometimes stagger the intake valve
openings and closings to promote tumble and provide a turbulence inducing
flap (retractable) in the intake tracts.

The cylinder head mods work; I've been using them for 25 years.  I even did
a 10:1 110 '65 Greenbrier (now in Albuquerque) that ran very well (yes, on
Premium)

Craig Nicol