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<DIV>Bob,</DIV>
<DIV> </DIV>
<DIV>There were changes made to the headers to make them better. However I
can help you make a change to yours to make it as good.</DIV>
<DIV>Basically I will give a story of the way the headers were designed since I
was involved. I can also tell you what the changes did and why they were made.
The result is the functional part of the header is the same for even the early
prototypes that I ran back in 2003</DIV>
<DIV> </DIV>
<DIV>The original ones I flew and I don't know that many of these got out other
than "Prototype versions" They had an aluminum bushing nut to hold the header
onto the motor. These work well However it was difficult to tighten them
up as the material was aluminum and so was the head. Yes it was a different
aluminum alloy than the head as we felt this would help in the heat and
expansion properties to keep it tight. Remember back we had been using steel
nuts on the headers. So a change was made very very early on to use a steel
bushing nut. This was a simple change and the bushing was just replaced. No
other change was made at the time and the header was put into production for the
first batch. Some people were still having trouble with the bushing nut coming
loose. If you continued to run the header after it came loose...the harder
bushing nut would tear up the header body. This was a result of the header
coming loose. The other thing we were doing was using a High temp silicone. The
copper colored stuff. This kept the header from leaking and would seal it up so
it didn't come loose...but some guys still had it coming loose. Perhaps the
threads in the head were not clean or who knows.</DIV>
<DIV> </DIV>
<DIV>By the way I was not having trouble along the way in keeping it tight. What
I did do was fly it. Then pull the header and tighten it up while the motor was
hot right after the flight. If you put a little smoke on it while hot they would
stay great. An idea came up to but put a stop screw on the bushing so it
could not back out. A few tried it and the result was the bushing would loosen
just a little then the stop screw would kick in and the thing would tear itself
apart. Again same deal the bushing was hard material and the header was
soft.</DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>Then we started to re-examine the problem with fresh eyes. The Hatori
headers and old NMP headers never came loose? Why. The copper washers inside the
head of the motor. If these would smash down too much then the header would come
loose. Light bulb went off we need a copper washer in there. But it can't go
inside the head. This would prevent the bushing nut from tightening up on the
head. So it needs to go on the bushing right inside the header right?</DIV>
<DIV> </DIV>
<DIV>In the mean time I had helped some guys with their headers and noticed that
some of the motors had a casting line that cut right through the exhaust port.
Since this surface was not flat or near flat there was no way for the header to
stay tight. In the mean time we were redesigning the body of the header to take
internal copper washers. So we decided to put a washer inside the header on the
bushing nut like an internal lock washer...and stick one between the head and
the header to seal a not so great fit sometimes at this connection point. When
the design was changed the header got slightly bigger to accommodate the
internal washer and the mounting surface was made thicker to help prevent the
tear itself up action. We also put a groove on the face to accommodate a washer
between the head and header. At this time another change was made to the bushing
nuts. We were adding 2 washers and the thread depth of the bushing nut was not
as good as we liked. SO we decided to change and make the bushing longer to
account for the washers. In doing this we found out something we learned years
ago. Not all the YS engines have the same thread depth inside the exhaust port.
Some are deeper than others Even 2 160's from the same batch would be slightly
different.. So in some case a 3rd washer was needed to keep the bushing nut from
bottoming out inside the head. Again this was not a functional change the change
was made to use a longer bolt because we were stacking washers on it.</DIV>
<DIV> </DIV>
<DIV>OK lets back was up. The design physically changed to make it more robust.
But the mechanical function has not changed at all. I had about 10 different
headers that were testing going back to the original concept about a year or
more before this final stage. The way the system works is the same its just that
we now have a soft material that will expand faster than the aluminum to keep
everything tight. On these older headers what I did do was install a single
copper washer between the head and the header. This is an easy
accommodation and requires no changes to the header or its parts just the
addition of the washer. So you get the exact same properties even though it may
not accommodate all the improved features. I am still running these old original
headers with a single washer between the head and header. This is 2-3 yrs
later.</DIV>
<DIV> </DIV>
<DIV>So you need to contact Central and get some of the copper washers. It is a
special size made just for this header. But they are cheap.</DIV>
<DIV> </DIV>
<DIV>Then look at a couple things.</DIV>
<DIV> </DIV>
<DIV>1) remove all internal copper washers that may be down inside the exhaust
port from using older headers. These will make the bushing tighten up but the
header will not be tight on the head. </DIV>
<DIV> </DIV>
<DIV>2) make sure the surface of the exhaust port flange is flat. It need not be
a machined surface just no mold flashings or bumps.</DIV>
<DIV> </DIV>
<DIV>3) Clean the bushing with acetone or the likes to remove the oil and grime
from it. Carb or Brake cleaner works well too.</DIV>
<DIV> </DIV>
<DIV>4) Install the header and stick a single or maybe even 2 washers between
the header and the head. I think you only need one but others with argue. I
helped design it and am confident one will work as good as two.</DIV>
<DIV> </DIV>
<DIV>If it ever comes loose again.....</DIV>
<DIV> </DIV>
<DIV>5) run the motor and while its hot right after shut down tighten the
bushing nut again. It won't come loose.</DIV>
<DIV> </DIV>
<DIV>There are some other guys that run the newer header brace and it works well
also. Again its probably not needed but depending on how your pipe/muffler is
supported it might be an advantage. I always mount my pipe at the front neck
where the header attaches to the pipe and then at the stinger. If you do this
then the pipe is not whipping around and putting forces on the header. Some guys
feel mounting the pipe at the CG of the pipe is the best way. Ok fine if this is
you then use the brace to keep the forces from being transferred to the header
and the bushing nut connection.</DIV>
<DIV> </DIV>
<DIV>If you continue to have any problems let me know and I can help you out
offline.</DIV>
<DIV> </DIV>
<DIV>troy_newman<A href="mailto:troy_newman@msn.com">@msn.com</A></DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>Troy</DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=THERUPMAN@aol.com
href="mailto:THERUPMAN@aol.com">THERUPMAN@aol.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, February 12, 2006 11:23
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [NSRCA-discussion] NMP
Headers</DIV>
<DIV><BR></DIV>
<DIV>Help needed,</DIV>
<DIV>If this has been covered before, just point me to it.</DIV>
<DIV>I've got a YS FZ in a QQ Yak with an early NMP hdr.</DIV>
<DIV>I'd like to say I've installed it per instructions, but sometimes I miss
something.</DIV>
<DIV>Anyway. Every flight loosens the header connection to the head. The cap
connection stays tight, but it does have the small screw to keep it from
backing out. Engine runs fine. Any help would be appreciated.</DIV>
<DIV>Bob Ruppel in Nashville</DIV>
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