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brian257

Well Known Member
It has come time to address the uneven mixture in my carbureted O-360. I have one cylinder running a bit leaner than the others and one one running a bit richer and two in the middle with the expected CHT differences. Although my engine is probably pretty typical for a Lycoming with a carb I want to get the mixtures as close together as I can before I start working on the cooling system and evening out the temps.

I have heard of others doing some type of turbulators in the induction system or other tricks to even things out, but I wanted to get some tips from people that have done this before I just start experimenting. My exhaust is a 2 into 1 on each side and the way it is set up it will be a lot of work to change so hopefully I can make whatever changes I need on the induction end and not mess with the exhaust.
 
carb heat and cracked throttle

Hi Brian,

My O-320 has bad mixture distribution unless I run partial carb heat or crack the throttle a bit. A little power is lost, but I have run smoothly LOP with good results like this for over 1500 hours. It fact you can "steer" the mixture with varying amounts of carb heat and watch CHTs change.

No extra parts needed. Just a thought if you have not tried it.
 
Yup, I'm with Pete on this one. Backing the throttle off just a little tips the butterfly in the airflow and seems to help with mixture distribution. Adding carb heat does likewise. While I can't say I have direct RV experience, I've seen this in action in the certificated aircraft I fly. It has a click detent type of mixture control where about 8 clicks is normal leaning for a typical flight at 4500 feet. Pull a bit of carb heat and you can get another 4 clicks of leaning before any roughness is noted (a drop in power is perceived at about 10 clicks total). Up higher at WOT, throttling back about 3/8" of throttle travel is good for another couple of clicks of leaning.
 
Both of these do work some, but I already cruise at 65% power or less and I am trying to get the mixtures as even as possible at all throttle settings.
 
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