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  #11  
Old 09-16-2013, 03:17 PM
penguin penguin is offline
 
Join Date: Jan 2005
Location: England
Posts: 1,087
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Hey Dave,

I did the same thing as you about 8 years ago. The engine will run happily with the old carb - but after everything is broken in it is likely that yours CHTs will be higher than you really want. I worked really hard to ensure the baffling sealed well, and ended up enlarging the main jet by 0.004" - some have enlarged by 0.007". That got the CHTs under 400F most of the time. Adding louvres in the bottom cowl (6A) dropped the CHTs by another 40F - almost too cold in the winter. If I had a grand to spare I would install a Pmag - no question.

I would fly and see where you are.

Pete
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  #12  
Old 09-16-2013, 03:35 PM
Zero4Zulu Zero4Zulu is offline
 
Join Date: Nov 2008
Location: Scio,Oregon
Posts: 261
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Quote:
Originally Posted by penguin View Post
Hey Dave,

I did the same thing as you about 8 years ago. The engine will run happily with the old carb - but after everything is broken in it is likely that yours CHTs will be higher than you really want. I worked really hard to ensure the baffling sealed well, and ended up enlarging the main jet by 0.004" - some have enlarged by 0.007". That got the CHTs under 400F most of the time. Adding louvres in the bottom cowl (6A) dropped the CHTs by another 40F - almost too cold in the winter. If I had a grand to spare I would install a Pmag - no question.

I would fly and see where you are.

Pete
I'm curious to know what the effect on fuel economy is before and after opening the jet?
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  #13  
Old 09-16-2013, 07:00 PM
Randle Randle is offline
 
Join Date: Dec 2012
Location: Atascosa, TX
Posts: 106
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Fuel econony will not be affected by opening the jet a couple of thousands. It can almost be like comparing an O-360's cruise consumption to that of a 320's. It is all dependant on the throttle operator. Many times the main reason in opening it up is to make the motor "happier", or closer to its most capable power curve, not to make more top end power.
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  #14  
Old 09-17-2013, 02:56 PM
penguin penguin is offline
 
Join Date: Jan 2005
Location: England
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Quote:
Originally Posted by Zero4Zulu View Post
I'm curious to know what the effect on fuel economy is before and after opening the jet?
I use the red knob to aggressively lean whenever I can, so the period of time spent at full throttle, full rich is not that long. Consequently I can't say I really noticed any great increase in fuel consumption. My max fuel flow is about 13gph (52 lit/hr). I typically operate around 6 to 7 gph (24 to 27 lit/hr), which is good for 135 to 140kt.

Pete

PS Link to Rotec TBI thread http://www.vansairforce.com/communit...ad.php?t=76405

Last edited by penguin : 09-17-2013 at 03:05 PM. Reason: added Rotec link
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