[SPAM] Re: Webra 145 pump pressure ?

[Paul Horan]

Eric,
    The pipe I am using is the pipe is a 15 cc Macs quiet pipe, 27 " from plug to first baffle.
    Tank position is already set with back of the tank at the CG.  The tank is above the needle by a about 2.5 ".  I have tried this 
engine with and w/o the pump, the pump does make substantial difference in needle setting, so it is working.
    Regarding castor, I am using it as insurance against a lean run, particularly since I am getting brownish oil in the exhaust at 
the mid-range.  Once it is broken - in and I have consistent results in the midrange I plan to reconsider the castor.  Usually I do 
not mess with castor - too much trouble with varnish.
Thanks,
Paul

----- Original Message ----- 
From: "Grow Pattern" <pattern4u at comcast.net>
To: <discussion at nsrca.org>
Sent: Wednesday, April 06, 2005 10:53 PM
Subject: Re: Webra 145 pump pressure ?


> Paul,
>           I have been thinking about your Webra problem. Your rpm seems too low for that prop.  I was wondering which MAC pipe you 
> are running? I have found the 145 to be a bit fussy in the mid range if the pipe volume is not big enough. It also needs a good 
> taper at the front of the pipe to get a good transition. Your pipe could be partially blocked?
>
> The OS 1.40 pipe, and/or ES CF clone pipe, has proven to be a good pipe for this motor.
>
> I believe that you are right about the pump but it is also related to tank position. The pump does not deliver quite enough fuel 
> in the mid range which might be why it is getting hot on sustained 1/2 throttle. You can help your pump perform by moving the tank 
> forward a bit.  If the back of the tank is on the CG it does not seem to mess much with the flight CG as it drains fuel.
>
> Quite a few folks have richened up the pump with good results. I would try the above external changes first before you start 
> messing with it.
>
> A big "no!" to Castor content. Just fit the new BOCA stainless steel bearing. I would also soak the liner, ring and piston parts 
> in an Acetone/Lacquer-thinner mix to remove any shellac build up.
>
> Regards,
>
> Eric.
>
>
>
>    My Webra has a good top and bottom end. Only about a gallon and a half through it so far.
>  The top end is nice and smokey, idle is solid, but the mid range is very little smoke.
>  It is on a Prophecy running a 16.5 x 12 at 7300 rpm with the Macs pipe  at 27  inches.
>
>  Most of my flight is at roughly 1/2 throttle. When I land the oil  residue on the coupler and
> fuselage is medium brown - fuel is a mix of 20 % synthetic and 5 % synthetic.  Main needle is open 1.5 turns.
>  am wondering if I should increase the pump pressure to richen up  the midrange.
> Or am I just being too fussy ?
> Thanks,
> Paul Horan
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