[Pattern] 3M-140 For Sale

[Jerry Budd]

>Hey Jerry,
>    which engine do you prefer: the OS1.40RX or the Webra 1.45? Why?
>    Thanks,
>      Will B.

Hi Will,

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.

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