Steve Dold (by way of Mi Vida Loca ) wrote:
>
> Bill, just send the answer to [EMAIL PROTECTED]
>
>
> We have a problem with the Continental 90 in the M-10, and I wanted to
> see if any of you have seen this before. The symptoms are:
>
> * Excessive RPM drop on only one mag (either one). About 200 RPM,
> with occasional backfiring in 1600-2000 RPM range.
>
> * Mag drops at 1500 RPM or below are only 25-50 RPM.
>
> * Engine has trouble taking power above 1500 RPM, but above 2000 or so,
> it seems to have no problem.
>
> * In this "bad" rpm range from about 1600-2000, leaning does not
> cause a rise, but a drop as the control reaches about halfway out.
>
> * Engine reaches full-power, with full RPM, and the mag drop there is
only
> 50 RPM or so.
>
> >From all of this I'm assuming that (probably) the carb is running lean
> in this range. Here are the "knowns":
>
> * It has always had this symptom to some extent, but was usually
attributed
> to fouled plugs and what-not. Lately it has gradually become more
> pronounced.
>
> * The carb was just overhauled by yours truly, with the supervision of
an
> IA.
> No obvious problems were found. Float levels are correct, and fuel
flow
> and pressure to the carb is fine. We did it by the book.
>
> * The carb is an MA-3 with the single-piece venturi added per AD, before
> we got the plane. It has no "economizer" jet.
>
> * All cylinders are new Milleniums. They don't have any obvious
problems,
> except that they all have oil in them. The AI attributes this to the
> fact that the rings haven't fully seated yet. They have about 3 hours
on
> them. This rough-running condition existed before the cylinders were
> replaced, but not to this extent.
>
> * The engine has new Slick mags, and the timing has been checked and
> rechecked.
> Again, this problem was there before the mag change. New harness and
plugs
> too.
>
> Those are the facts. Anybody have any experiences like this? I don't
think
> it's a fuel-flow problem, because full power seems OK. The AI says he
thinks
> he remembers something about the one-piece venturi causing mixture
problems
> in some cases. Anybody heard this one?
Steve,
When the single venturi is in stalled, there is a port in the carb
wall under the venturi that may be partialy blocked. This is a air bleed
to the carb float reservior which lowers the pressure in it to allow the
fuel flow to adjust to the throttle demand. Check this and any blockage
to the air vent circuit to the reservior. Also check for the free kit
from Precision Carb to eliminate these problems as mentioned in the AD
and service note. There have been rough running engine problems with
this mod. I did the mod on my Cessna and put the kit in when I replaced
the venturi and have had no problems. The kit has a feed pipe with more
holes than the original that it replaces. It is in the reservior area.
Let me know what you find.
Bill L<<attachment: winmail.dat>>
