OS 140 and Greve pipe question

[wgalligan]

Lance Vanodstrand and I did some testing on his airplane with the O.S. and grieve pipe.  He had the length too long and couldnt seem to get enough power.  The pipe was way too long.  We shortend the pipe and he got much better results.  Try shortening it a little at a time till you reach a peak rpm and if the rpm drop after shortening it then back it off about 1/4-3/8".   You should be able to turn a 17x12n APC about 8400rpm on 15% fuel O.S. "F" plug.  You could have other issues but this is what we found on the tuning part. 

Wayne
    -----Original Message-----
    From: GW <gw at gwair.com>
    To: discussion at nsrca.org <discussion at nsrca.org>
    Date: Saturday, April 26, 2003 11:04 AM
    Subject: OS 140 and Greve pipe question
    
    
    Can someone let me know the proper setup lengths for this engine and pipe combo? OS 140 /Greve pipe.
     
    I have tried many different lengths on the pipe, and many different setting on the needles, and I still have a very rich midrange that the engine cannot overcome. The engine will reach max RPM if I go from idle to full throttle in a quick transition, but with a slow advance of the throttle from low to high, it stumbles,spits and sputters from mid throttle on and often just quits after a few moments of stumbling.and never reaches max rpm.
     
    I have run the pressure adjust on the pump out up to 1 1/2 turns to reduce pressure, with little or no change.
     
    I am about to install a 3M head with dual plugs to see if it will help.
     
    As a side note, I have a CD products Muffler (very restrictive but quiet) and the engine runs flawlessly on this setup, Transition is perfect, but this setup will not fit in my new CA Models Eclipse, so the Greve needs to work!
    Any advise?
    
    Thanks
    GW
    Gerald
     
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