A flycutter is not capable of opening valve pockets or ports.   To do
that, you need long shank (or an extension mandrel) cylindrical, tapered
and olive shaped steel double-cut carbide tool bits for an air-powered
handheld die grinder.  Another way to drive them is to put these bits
into a Dremel or Roto-Zip flexible extension shaft tool.  This keeps it
small, light and keeps the hot, heavy electric motor out of your hands.
Keeping the bits well-lubed with a shot of WD-40 every couple of minutes
keep the bits from getting clogged with the soft aluminum.

Mike B.

On 5/10/2013 11:02 PM, Scott Daniel - Turbovans wrote:
> 'pocket width' .....
> 'pocket' in cylinder heads to me means the area the valves sit in
> ...like how much relief there is around them.
>
> porting also comes to mind, but you'd think the term 'port out' or
> something like that would have been used.
>
> On 5/10/2013 7:08 PM, Ben wrote:
>> Sounds to like the young man is looking for a "flycutter". Chuck it out.
>>
>>
>> BenT
>> sent from my electronic leash
>>
>> On May 10, 2013, at 6:28 PM, den jolliffe <sondancer77@YAHOO.COM> wrote:
>>
>>> I'm looking to open up the pocket width on some air cooled heads for
>>> an engine build on my 81 camper...trying to find a little more
>>> HP...just a little.
>>>
>>> I recall there was a cutter in my collection some 25 years ago to do
>>> this kind of thing, but most of that stuff is long gone once I
>>> closed the shop...now I'm looking for it again, go figure.
>>>
>>> Can anyone enlighten me....same tool will help me open up some 1.7
>>> heads for another project and move it to drivability for the
>>> summer...been at that one nearly 10 years, so it's time.
>>>
>>> Thanks, Den.