O-320 way rich after Major + 160HP conversion + Powerflow

No, that will be next. I think there are actually 2 STCs, one for the
exhaust (Powerflow) and one for the 160 HP conversion (Superior Air Parts, I
think). I wonder if the problem is in combining these 2 STCs?

"Ron Rosenfeld" wrote in message
...
On Thu, 1 Apr 2004 18:42:17 -0500, "Dave Gribble"
wrote:

This is the exact procedure we've used to set the mixture. The idle is
650
rpm and the increase when you move to cut-off is only about 25 rpm.

The problem is that it still seems too rich, especially in the pattern
with
carb heat on.

Then there is something else going on besides the mixture adjustment.
Have
you checked with the folk that hold the STC for the engine and exhaust
mods?


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

On Thu, 1 Apr 2004 22:15:16 -0500, "Dave Gribble"
wrote:

No, that will be next. I think there are actually 2 STCs, one for the
exhaust (Powerflow) and one for the 160 HP conversion (Superior Air Parts, I
think). I wonder if the problem is in combining these 2 STCs?

I suppose it could be. But the 160HP converted engine should be listed as
an allowable engine for the Powerflo system. Or vice versa.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

On 1-Apr-2004, Ron Rosenfeld wrote:

No experience with the O320, but with the Lycoming O360's, the procedure
to
set proper mixture should be doable on the ground.

1. Start engine and warm up until CHT's and oil temps are normal.
2. Mag check -- if normal, proceed.
3. Set throttle set screw so idle is per airframe mfg recommendation.
4. Slowly move mixture control towards idle cut-off and observe rpm. An
increase of more than 50 RPM indicates the mixture is too rich. (An
immediate decrease, if not preceded by a momentary increase, indicates the
mixture is too lean).
5. When performing step 4, don't let the engine cut out.
6. Adjust the mixture control in the proper direction; run up to 2000 RPM
to "clear" the engine, and repeat the above as necessary. If the mixture
change has changed the idling RPM, that should be re-adjusted as needed.
7. If the setting does not remain stable, check the idle linkage for
looseness.


If the goal here is to set the mixture control linkage so that "proper"
mixture occurs with the control at the full lean position, then this had
better be done at or near sea level density altitude. How is the procedure
done on the ground in Denver?

--
-Elliott Drucker

On Fri, 02 Apr 2004 01:52:36 GMT, wrote:

If the goal here is to set the mixture control linkage so that "proper"
mixture occurs with the control at the full lean position, then this had
better be done at or near sea level density altitude. How is the procedure
done on the ground in Denver?

I don't know. All the manual says is that an "allowance" should be made
for setting idle for weather conditions and field altitude. It doesn't
state how to compute that allowance.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Deakin's had an AvWeb column sometime in the last three months on
setting the proper ground mixture.

Dave Gribble wrote:

The O-320 in our C-172 was professionally recently professionally overhauled
(at 2300 hours and 32 years). This included an STC to 160 HP, new
millennium cylinders, new crank (a story, there..), new cam, new carb, a
repitched prop, and a powerflow exhaust.

We're past break-in now, and the plane flies great, climbs awesome. The
recurring problem is that the carb is set way too rich. After a few visits
to the A&P (each time involving a lot of carb twiddling), it is getting
better each time. It is rich enough that I find that carb heat in the
pattern induced pretty good roughness and often backfiring. In fact, I find
that I need to keep it leaned even on the ground or in the pattern (our
field is only 200' elevation). On the ground, the idle is at 650 with the
mixture in, put pull it out about an inch or 2 and it gets a lot smoother
and a little bit faster.

The mechanic feels that it will take us a few iterations to get it set up
right, since there is so much new stuff here. He feels that the exhaust may
be a big part of this.

One other clue, the EGT now reads a lot lower than it used too. They are
apparently going to re-calibrate the thermocouple so it will at least
register on the gage.

Anyone have any experience like this?

Thanks,

dave

Dave Gribble wrote:

This included an STC to 160 HP, new
millennium cylinders, new crank (a story, there..), new cam, new carb, a
repitched prop, and a powerflow exhaust.

I installed tuned headers on a van once. It ran rich after that, due to the reduced
back pressure. I had to rejet the carb to fix it. That leads me to suspect your new
exhaust, but you've put a new carb on there too. Can you put the old one back on for
a flight?

George Patterson
Treason is ne'er successful, Sir; what then be the reason? Why, if treason
be successful, Sir, then none dare call it treason.