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

[Mark Corbin]

Craig,

That was the whole point in what I had done. BOTH the heads and pistons
were milled accordingly by Warren, so that the compression would remain the
same. So the only thing left is to blame today's lousy gas for the
dieseling.

-Mark


> [Original Message]
> From: craig nicol <nicolcs at aol.com>
> Subject: <VV> Head milling, was: PG Turbos??
>
> <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