Anderson Ed wrote:

Hi Folks

Had my 13B powered RV-6A aircraft out for a flight Sunday 21 Feb.  OAT
was 29F.  When I started the engine, it ran very rough until it warmed
up. It may have been overly rich as there was no backfiring or
poping.However, I tried adjusting the cold start mixture as it was
coughing and chugging but it did not appear to make any improvement.
After approx 5 min warm up it ran fine.

After an 1 1/2 hours of flying I decided it was just to D___ cold and
decided to let down from 8500 ft and retarted the engine rpm to 4300
where the engine began to run rough again (although not nearly as bad as
on start up).  I headed back to the airfield and was concerned about it
continuing to operate at lower rpm.  I got the airspeed down below 100
MPH and then set full flaps, so I could then keep the rpm in the mid to
high 4000 range where it appeared to operate smoothly as long as under
load.

Tracy, I remember you mentioning that you had some rough running due to
spark plug deteriotation, did not recall that until after I left the
airport for home.  I did discover a couple of flights ago that I was
running way too rich >6000 rpm and had reduced the injector timing until
reducing the mixture control knob to lean would cause the engine to
change sound and EGT to go up.  I am now wondering if my leaning the
engine would have considerably shortened the life of the plugs.  I am
using single electrode plugs rather than the stock.

Any thoughts - I will pull the plugs this coming weekend, but thought I
would inquire as to anyother possible causes before I tear into the
problem.

Ed Anderson
RV-6A N494BW

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