REFLECTOR: Running LOP

[Dave Philipsen]

Andy,

Even though your question was directed to Steve, I thought I might jump 
in and give you some information I have learned.  I've communicated via 
email with a guy who owns a Cessna Cardinal which has a Lyc. IO-360 
engine.  He claims that he has tuned his injectors by finding the first 
cylinder to peak (when leaning) and then removing the injector and 
"worrying" the orifice open just a little bit with a miniature drill 
bit.  He also mentioned that he has tweaked his injectors to the point 
where he has a maximum of 0.3 gph difference between the richest and the 
leanest and thinks if he tried he could get it down to 0.2 gph or less. 
I think the orifice size would put you in the range of a #69, 70, or 71 
drill and you apparently have to be very careful that you don't ream out 
too much.  He said he went overboard on one of the injectors and had to 
end up buying a brand new one from Lycoming and starting over.

I've had my injectors out and I experimented with some miniature drill 
bits just to see how they fit without actually drilling the orifice.  In 
doing so, I did find out that some of the injectors fit the drill bit 
snugly as I slid it in and others had notably more "play" indicating 
that they weren't all *exactly* the same size.  I would imagine the 
difference was less than .001 inch though.

I'm in the middle of an engine annual right now and also fitting a Dynon 
EFIS to my Velocity.  But as soon as I get the Dynon wired to the CHTs 
and EGTs I plan on doing the same thing and tuning the injectors to 
attempt to get them all to peak at very near the same time.  This should 
allow the engine to run smoothly on the lean side of peak.  Right now, I 
can run LOP with just a little roughness that is tolerable.




Andrew Ellzey wrote:
> Steve,
>
> Can you elaborate on how you are tuning your injectors?
>
> Andy Ellzey
>   

-- 
Dave Philipsen
Velocity STD-FG
N83DP