OS 1.4 Rookie

[Jerry Budd]

>I'm the proud (?) owner of a 1.40, non EFI....what's the current 
>reliable, best working setups???  Please??  Props, pipes, tuning 
>info??
>
>Bob Pastorello, Oklahoma
>IMAC 1320, AMA 46373
><mailto:rcaerobob at cox.net>rcaerobob at cox.net
><http://www.rcaerobats.net>www.rcaerobats.net
>
>

Hi Bob,

I posted the following a while back (3/30/03), you may find it of 
some value.  After putting another 25 or so flights on the Webra the 
peak rpm climbed to just over 8600 at the Riverside contest (in mid 
April).

Thx, Jerry


>I like the Webra a bit better than the OS but they both have their 
>merits.  I'm running them interchangeably in the same airplane 
>(E=MC3) on Magnum #1, OS-F or YS plug, ES-2C140L90 pipe set at 
>23-1/4" baffle to plug, stock Mac's 2-1/4" rise header, and an APC 
>17x12 prop.  Here's the differences:
>
>Webra:  8200-8300 rpm with the Webra MC (mixture control) carb gives 
>a dead linear throttle response with NO jump onto the pipe.  Setup 
>this way the motor performs and throttles exactly the same as a DZ. 
>With the stock ProMix carb it throttles a lot like the OS (see 
>below).  This is with a relatively new, low time motor (~20 flights).
>
>OS: 8300-8400 rpm with the stock OS carb, slight burble at mid-range 
>transition, moderate jump onto the pipe around half throttle.  The 
>motor goes slightly lean momentarily during inverted pushes during 
>the second half of the 20 oz tank.  My first OS in the same airplane 
>exhibited the same characteristic.  This is a motor with around 30 
>flights on it.
>
>The OS carb has a somewhat bigger throat than the Webra carb which 
>probably explains the power difference, but may also cause the 
>throttle linearity/burble/momentary lean discrepancy.  The OS also 
>seems to have significantly more bearing problems, although that 
>seems to be corrosion related and managed by switching to stainless 
>steel bearings.
>
>I think the 3M-140 motor is comparable to an average OS in power, 
>but it throttles much better in the mid-range.  It would make an 
>excellent motor for a 9.75-10.5 lb mid-body airplace such as a 
>Focus, Temptation, HydeAway, Angel's Shadow, etc.


-- 
___________
Jerry Budd
mailto:jbudd at qnet.com
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