Here are some more pics.
Notice how the short tube seats in the counter bore
just short of the steel liner.
You can use a high quality 1.5 inch hole cutter
instead of this shell mill to rough it out before
final boring.
--  Paul Lamar ...No rotor no motor.

This part has people scared but there is nothing to it.  It has been
awhile but I think I drilled a 1.25 i.d. pilot hole and then opened
up with a boring head.
.  It does not take long.  One practice hole and you will have
confidence to do the real thing.     Jerry

Here is an interesting thread that Cary Beasley found where the builder
shows using  a hole saw to make the final hole.
http://www.rx7club.com/showthread.php?t=144200&page=1&pp=15

Even if you plan to finish with boring tool, the hole saw would be
cheaper than a big end mill and safer than a fly-cutter to make the
rough cut.  You will need a high quality bi-metallic (such as Dewalt)
hole saw.  Drill the pilot hole as a separate operation.  Replace the
pilot drill in the hole saw arbor with a solid rod to guide the hole saw.

It occurs to me that if you mount the hole saw in the mill and gently
dress the tooth set on the outer edge with a die grinder, that it would
make a hole with a surface finish very nearly as good as the boring
tool.  The tube could then be turned to fit to the hole.   One benefit
of doing it this way is that you could set it up for the cut with a much
less rigid angle plate.

Aubrey

Hey Aubrey;
Sounds like you are thinking PPort!
I did a test run on a boat-anchor12A housing with a lathe, hole saw,
flycutter and digital calipers. - I recommend a test run, if for nothing
other than warm and fuzzies before cutting a hole and inserting a sleeve
into perfectly good housings...

I happily trued up a cheap $7 bi-metal hole saw on a lathe (3 housings
and going).  I threw some more comments in towards the end of the
rx7club.com thread above  - it's worth a few hours reading.  The hole
saw method required a LOT of cutting fluid due to friction (both true
each other up into a measureable conical shape rather quickly).  It does
create a rather smooth hole but requires either VERY careful flycutter
use/insert fitting or a boring head arbour to finish.  The pilot
hole/solid rod guide helps but beware of vibration (I broke one 1/4 rod
guide due to poor milling machine mounting/vibration damping).
The easiest solution is to cut undersize and finish with a cheap Chinese
$40 boring head arbour and matched tubing.
Take your time and measure, measure, measure.
Cheers
Cary

Hi Cary,

I got some junk housings and am ready to bore now that I have been released
from the housing building project:)  You mentioned 3rd gen housings are
preferred.  Which housings and why?

DougFir

Hi Doug;

Sorry about that, what I meant to say was that I have 3rd Gen (iron)
end housings which have better oil pumping capability.
I'm seeing lots of things that need to be corrected after I sent it out.
I should also have drawn some circles to highlight things.
Let me know if anything else if unclear.

Cheers
Cary



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