[NSRCA-discussion] NMP Pattern Header

[Jim Woodward]

Guys,

 

I sold off nearly all my E stuff (only the Tanics left) and my trusty OS 140
RX setup.  Running YS now, I jumped into the new style of short Hatori pipe
/header combination from Central Hobbies (P/Ns 822,821).  This setup looks
to save about 2.0 oz over the Johnson header/Teflon coupler/Hatori pipe
combination.  The installation is super clean and the muffler comes with
“ears” and “stand-offs” for the mounting.  No more zip ties!  You just screw
the muffler flanges down to the pipe standoffs.  The muffler has an O-ring
that slip-fits onto the exit area of the header.  As there is no retention
force of this attachment method, you must use the flange mounts to prevent
the muffler from sliding aft.  

 

The header is steel and appears solid, but not overly done.  The
installation process is as follows:  pass hollow bolt through mounting
flange, position brass washer over hollow bolt, screw hollow bolt into the
motor and tighten down the flange.  Position gasket over flange, install
header onto flange using the three metric screws.    Once the header is
installed, the hollow bolt is completely concealed.  The only tip on usage I
have is that it takes a few tries to get the “tightening” procedure down.
As you tighten the hollow bolt, the flange will rotate in the last ¼ turn.
Thus, you must ensure that when the proper tightness is achieved, the flange
mounting pattern ends up in the correct position for the header to point
down the center of the pipe tunnel.  150 words to explain, 5 seconds to
understand once you have the system in hand.  

 

My only idea for improvement to the header/flange system would be to install
it first, then drill and tap an additional screw point into the system.
This extra screw should be positioned such that extended portion of the
screw fits in between the cooling fins of the motor.  After installed, cut
off the head of this new bolt.  What this would allow to happen is for the
flange to be positioned 100% correct when you re-install it, and prevent it
from rotating as the hollow-bolt is tightened. Instead of having to tighten
and reposition a few times to get it right, you would be able to tighten it
one time as there would be this new anti-rotation pin protruding from the
backside of the flange.  

 

However, GREAT system the way it is too – same one Sean was using at the
2006 nats.  Looks like header breakage is a thing of the past with this
setup.

 

Thanks,

Jim W.

 

  _____  

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Peter Pennisi
Sent: Wednesday, August 23, 2006 9:34 AM
To: 'NSRCA Mailing List'
Subject: Re: [NSRCA-discussion] NMP Pattern Header

 

Don,

 

I am having good results with mine – 200+ flights later and going strong.
You need a brace and you need at least 2 washers between engine and header +
I washer inside – Total of 3 washers to be used.

 

 

 

  _____  

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Don Filteau
Sent: Wednesday, 23 August 2006 2:23 PM
To: nsrca-discussion at lists.nsrca.org
Subject: [NSRCA-discussion] NMP Pattern Header

 

HI People

 

I just got back from the flying field.  My NMP Header blew off my 160 YS.
It pulled the threaded part that holds it to the engine through the header
part. Has anyone had this happen to them? I have only put 5 gallons through
this engine.  I am turning a 16.5x12.5 W APC at around 8500 rpms.  I am not
sure if I like this header.  What are other people using on their 160'S?  I
can take pictures to show people if they like.

 

Don

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.nsrca.org/pipermail/nsrca-discussion/attachments/20060823/0d4467aa/attachment.html