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Date: Thu, 19 Nov 2009 23:28:22 -0500
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Subject: End and intermidiate irons.
From: Lynn Hanover <lehanover@gmail.com>
To: flyrotary@lancaironline.net
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When rebuilding the 2nd gen do the cast iron housings need any treament or
can they be used as is?  Cylinders ina piston engine are usually honed so
new rings can seat what about side seals? Thanks for any help

Joe Berki
Below is an answer that I posted on the "Nopistons" news group. A good
source of rotary information.

http://www.nopistons.com/forums/forums.html

This applies to street engines and competition engines in severe use.

You can lap the surface youself and you can get it ready with a random
orbital sander. Used dry with 180 grit paper,
this alone will get most of the surface close to one color. You can run the
front iron against the front side of the center iron with oil and valve
grinding compound in between. Wipe it off now and then to be sure all of the
surface
has a flat finish with no shiny spots. This will produce a very satisfactory
result on both irons. About half way through, rotate the top iron 180
degrees so the ports are not together the whole time. If you have a mill or
access to one make a bar and plate with holes in the plate to mount a
bearing on a bolt. Plant the bearing in the center hole, so it impinges the
iron about one inch. Run the mill slowly and keep adding grinding paste as
you go along.
A few layers of Visqueen under the bottom plate will keep the mill clean and
allow reuse of the paste. Bolt on a rod of some kind and run the rod through
a fixed bracket or just any bracket on the bed to keep the iron from
spinning. Then you flip the center iron over and do the same again with the
rear iron. If you drill press has an electronic speed control that allows
for very slow rotation, you can use it as well.

This method costs nearly nothing and produces very flat irons with a nice
oil holding finish. Clean the irons at the car wash with high pressure water
and soap. Spray with WD-40.

You can do this by hand as well, but it will take all day long. This can be
done quite a few times without bothering the nitride. Piece of cake. This
has to do with finish, and is not much help with wear grooves since it
removes very little material.

Lynn E. Hanover

There should be no attempt to reduce the surface enough to remove the wear
marks (Groove along the plugs side of the iron). This groove is caused by
hot metal wearing more quickly than cooler iron. So, the groove forms from
the side seal moving in a somewhat vertical path. The same exact wear would
occur on the opposite side but for the cooler iron. Right? The wear limit of
this groove depth is .004". It can be removed by grinding and lapping. That
is reducing the entire surface exactly the same amount. Or just lapping for
a very long time. Either operation is acceptable. The irons should be
renitrided after either process.

One light lapping probably would leave a nitrided layer since it starts out
at about .003" deep. This is for street engines that do not get disassembled
often. It makes no difference in a race engine.

You hone a piston engine cylinder to remove the glaze. That is the chrome
like finish of the bore walls caused by the rings wearing away some of the
surface. New rings installed in a slick chrome like bore will take years to
break in. The oil scraper ring will remove all oil from the bore on each
stroke and the new rings will spoil from over heating.

Same thing in the rotary. To remove the glaze. The shiny surface, and
replace it with a rough surface that will hold a supply of oil to help
lubricate the side seals. The side seals are the piston rings of the rotary.


The object here is to remove the glaze with the rather course 180 grit paper
on the random obital sander. A air powered 5" round aluminum oxide disc is
what I use, but an electric unit would be fine. I run the disc dead flat on
the iron long enough to remove all of the staining done by water in the seal
grooves. Go real light on the legs. Material comes off real fast with high
unit pressures, Then a fancy lapping session or glue some wet or dry
silicone carbide 400 grit paper to an old disc pad, and wet the iron with
kerosine and run over it again nice and flat just long enough to get a flat
grey look to it. About 5 minutes, and keep it wet. A new dry 180 grit disc
and a new silicone carbide disc for each iron face. You can do the wet part
in the cleaning tank for less mass making.

Then off to the car wash for a long wash and wrinse. Then dry with old clean
towels and spray with WD-40. Now you have a finish that will last through
several rebuilds. Provide quick break-in, and long life and high compression

form the side seals and corner seals. The swirl marks from the 180 grit will
outlast the irons.

Just don't use a synthetic oil in a fresh rebuild. Run a few hours with dino
oil, then dump it and change filters, and run what you want. If the OMP is
in use, a good brand of dino oil and if you premix, a synthetic racing oil
in the sump.

Lynn E. Hanover
There are pictures of a set of irons done with this method on the web site.

For irons that exceed the .004" wear limit (the depth of the groove along
TDC on both sides) you can surface grind to just reduce the surface to below
the .004" then treat as above. Or, surface grind to .003" and power lap to
zero groove depth. In most cases this will be through the Nitride, and the
irons must then be retreated. Early irons were not nitrided, and could
exceed the .004" wear limit before 100,000 miles. About 10 years of flying.
I would suspect you would look inside a few times before then.
With synthetic oils the irons might even last longer, Nitrided or not.
Lynn E. Hanover

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<div>When rebuilding the 2nd gen do the cast iron housings need any treamen=
t or<br>can they be used as is?=A0 Cylinders ina piston engine are usually =
honed so<br>new rings can seat what about side seals? Thanks for any help<b=
r>
<br>Joe Berki<br></div>
<div>Below is an answer that I posted on the &quot;Nopistons&quot; news gro=
up. A good source of rotary information.</div>
<div>=A0</div>
<div><a href=3D"http://www.nopistons.com/forums/forums.html">http://www.nop=
istons.com/forums/forums.html</a></div>
<div>=A0</div>
<div>This applies to street engines and competition engines in severe use.<=
/div>
<div>=A0</div>
<div>You can lap the surface youself and you can get it ready with a random=
 orbital sander. Used dry with 180 grit paper,<br>this alone will get most =
of the surface close to one color. You can run the front iron against the f=
ront side of the center iron with oil and valve grinding compound in betwee=
n. Wipe it off now and then to be sure all of the surface <br>
has a flat finish with no shiny spots. This will produce a very satisfactor=
y result on both irons. About half way through, rotate the top iron 180 deg=
rees so the ports are not together the whole time. If you have a mill or ac=
cess to one make a bar and plate with holes in the plate to mount a bearing=
 on a bolt. Plant the bearing in the center hole, so it impinges the iron a=
bout one inch. Run the mill slowly and keep adding grinding paste as you go=
 along.<br>
A few layers of Visqueen under the bottom plate will keep the mill clean an=
d allow reuse of the paste. Bolt on a rod of some kind and run the rod thro=
ugh a fixed bracket or just any bracket on the bed to keep the iron from sp=
inning. Then you flip the center iron over and do the same again with the r=
ear iron. If you drill press has an electronic speed control that allows fo=
r very slow rotation, you can use it as well.<br>
<br>This method costs nearly nothing and produces very flat irons with a ni=
ce oil holding finish. Clean the irons at the car wash with high pressure w=
ater and soap. Spray with WD-40. <br><br>You can do this by hand as well, b=
ut it will take all day long. This can be done quite a few times without bo=
thering the nitride. Piece of cake. This has to do with finish, and is not =
much help with wear grooves since it removes very little material.<br>
<br>Lynn E. Hanover </div>
<div>=A0</div>
<div>There should be no attempt to reduce the surface enough to remove the =
wear marks (Groove along the plugs side of the iron). This groove is caused=
 by hot metal wearing more quickly than cooler iron. So, the groove forms f=
rom the side seal moving in a somewhat vertical path. The same exact wear w=
ould occur on the opposite side but for the cooler iron. Right? The wear li=
mit of this groove depth is .004&quot;. It can be removed by grinding and l=
apping. That is reducing the entire surface exactly the same amount. Or jus=
t lapping for a very long time. Either operation is acceptable. The irons s=
hould be renitrided after either process. <br>
<br>One light lapping probably would leave a nitrided layer since it starts=
 out at about .003&quot; deep. This is for street engines that do not get d=
isassembled often. It makes no difference in a race engine. <br><br>You hon=
e a piston engine cylinder to remove the glaze. That is the chrome like fin=
ish of the bore walls caused by the rings wearing away some of the surface.=
 New rings installed in a slick chrome like bore will take years to break i=
n. The oil scraper ring will remove all oil from the bore on each stroke an=
d the new rings will spoil from over heating. <br>
<br>Same thing in the rotary. To remove the glaze. The shiny surface, and r=
eplace it with a rough surface that will hold a supply of oil to help lubri=
cate the side seals. The side seals are the piston rings of the rotary. <br=
>
<br>The object here is to remove the glaze with the rather course 180 grit =
paper on the random obital sander. A air powered 5&quot; round aluminum oxi=
de disc is what I use, but an electric unit would be fine. I run the disc d=
ead flat on the iron long enough to remove all of the staining done by wate=
r in the seal grooves. Go real light on the legs. Material comes off real f=
ast with high unit pressures, Then a fancy lapping session or glue some wet=
 or dry silicone carbide 400 grit paper to an old disc pad, and wet the iro=
n with kerosine and run over it again nice and flat just long enough to get=
 a flat grey look to it. About 5 minutes, and keep it wet. A new dry 180 gr=
it disc and a new silicone carbide disc for each iron face. You can do the =
wet part in the cleaning tank for less mass making.<br>
<br>Then off to the car wash for a long wash and wrinse. Then dry with old =
clean towels and spray with WD-40. Now you have a finish that will last thr=
ough several rebuilds. Provide quick break-in, and long life and high compr=
ession <br>
form the side seals and corner seals. The swirl marks from the 180 grit wil=
l outlast the irons. <br><br>Just don&#39;t use a synthetic oil in a fresh =
rebuild. Run a few hours with dino oil, then dump it and change filters, an=
d run what you want. If the OMP is in use, a good brand of dino oil and if =
you premix, a synthetic racing oil in the sump. <br>
<br>Lynn E. Hanover <br></div>
<div>There are pictures of a set of irons done=A0with this method on the we=
b site.</div>
<div>=A0</div>
<div>For irons that exceed the .004&quot; wear limit (the depth of the groo=
ve along TDC on both sides) you can surface grind to just reduce the surfac=
e to below the .004&quot; then treat as above. Or, surface grind to .003&qu=
ot; and power lap to zero groove depth. In most cases this will be through =
the Nitride, and the irons must then be retreated. Early irons were not nit=
rided, and could exceed the .004&quot; wear limit before 100,000 miles. Abo=
ut 10 years of flying. I would suspect you would look inside=A0a few times =
before then.=A0</div>

<div>With synthetic oils the irons might even last longer, Nitrided or not.=
</div>
<div>Lynn E. Hanover=A0</div>

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