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rearmounted carbs.

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Old 01-05-2012, 08:08 PM
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mmflytie
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Default rearmounted carbs.

Can someone comment onhow you mount engines with rear mounted carbs. Does going thru a hole in the firewall cause problems. seems like carb wouldn't get enough air inside nose of plane? I have a DA 85 going in an ESM Corsair.
Any help would be appreciated

Marc
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Old 01-05-2012, 08:28 PM
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Default RE: rearmounted carbs.

I have a DA85 and it runs fine. The carb goes through the firewall and the air is drawn in from around the inside of the motor box. The motor box itself has holes in the sides and top and bottom. I like the rear carb design from the standpoint that the engines can run the same right-side-up or upside-down. I have had several engines (DA100, 3W-100, DA170) that have carburetors hanging from the bottom of the crankcase and sometimes they run differently when they are upside down. This can be caused by fuel puddling. At low throttle settings there is not enough air flow to completely draw all the fuel into the combustion chamber. But upside-down, gravity assists and most of the fuel ends up going through the engine, richening it slightly as compared to when it was right-side-up.

The worst thing about the rear carb is sometimes it is more difficult to get at the needle valves because the firewall is in the way.
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Old 01-05-2012, 08:29 PM
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Default RE: rearmounted carbs.

you might have to fabricate a motor box . or use standoffs . it could envolve making the nose longer. if the carb is too far inside the fuse of the plane , tunning is too much of a problem . you want the needles , just at the back of the cowl. and in front of the firewall. if its a corsair with
a long nose , you might not have a problem
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Old 01-06-2012, 02:08 PM
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Default RE: rearmounted carbs.

It is a thing to get used to. Rear mounted carbs need a bit of rethinking the layout. That's all.
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Old 01-06-2012, 03:38 PM
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Default RE: rearmounted carbs.


ORIGINAL: mmflytie

Can someone comment onhow you mount engines with rear mounted carbs. Does going thru a hole in the firewall cause problems. seems like carb wouldn't get enough air inside nose of plane? I have a DA 85 going in an ESM Corsair.
Any help would be appreciated

Marc
its actually benefical to have a rear mounted carb, you dont have variable airflow that can affect side carbed motors, plus they produce more power due to the reed valve induction
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