Webra 145 pump pressure ?

[Randy]

I got more RPMS than this with a 17X12 on this motor with a greeve pipe.  I 
seem to remember around 8K.
Randy

----- Original Message ----- 
From: "Grow Pattern" <pattern4u at comcast.net>
To: <discussion at nsrca.org>
Sent: Wednesday, April 06, 2005 11:53 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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