Mags

: I'm running in my overhauled engine - 4 hrs - all a full rich.

: I don't understand why you would want to operate the engine without
: leaning. No recommendation I've ever read about post-overhaul break-in
: ever included anything like that.

For breakin (4 hours is a good minimum for when most of the breakin should
have occurred), you absolutely need to run at a very high power setting. High cruise
(~70%) is a minimum, but I've seen recommendations of 85% or so as well. At those
power settings, you'll need to have a very rich mixture to:
A) Prevent major damage from detonation
B) Keep the engine cool (CHT cooler than "normal" preferrably)

I've got an EGT in mine (now well broken in), and in a long climb I'll lean to
maintain EGT I get at takeoff (1400 on my plane). If you don't have that, you're
better off leaving it full rich while you fly around for a few hours at 85%. A few
hours at wicked rich isn't going to hurt/dirty anything... just reduce power (70%)
before landing and lean it until it wheezes cook out the carbon buildup.

-Cory

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

Just broke in 6 new Millenium Cylinders last July and their break-in
instructions said to run them at 100% for 2 hours at 3-4,000 feet. I did
this and the temps dropped after about 30 minutes showing the rings were
beginning to seat. They have run well since.


Trip

In article , says...

: I'm running in my overhauled engine - 4 hrs - all a full rich.

: I don't understand why you would want to operate the engine without
: leaning. No recommendation I've ever read about post-overhaul break-in
: ever included anything like that.

For breakin (4 hours is a good minimum for when most of the breakin should
have occurred), you absolutely need to run at a very high power setting. High c
ruise
(~70%) is a minimum, but I've seen recommendations of 85% or so as well. At tho
se
power settings, you'll need to have a very rich mixture to:
A) Prevent major damage from detonation
B) Keep the engine cool (CHT cooler than "normal" preferrably)

I've got an EGT in mine (now well broken in), and in a long climb I'll lean to
maintain EGT I get at takeoff (1400 on my plane). If you don't have that, you'r
e
better off leaving it full rich while you fly around for a few hours at 85%. A
few
hours at wicked rich isn't going to hurt/dirty anything... just reduce power (7
0%)
before landing and lean it until it wheezes cook out the carbon buildup.

-Cory

************************************************* ************************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************* ************************

TripFarmer wrote:
: Just broke in 6 new Millenium Cylinders last July and their break-in
: instructions said to run them at 100% for 2 hours at 3-4,000 feet. I did
: this and the temps dropped after about 30 minutes showing the rings were
: beginning to seat. They have run well since.


Exactly. "100%" at 3-4000' is probably 85-90% unless you're turbocharged.
Gotta run them hard and cool initially to seat them.

-Cory


************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

IMO, an indication of something not right in the mag. It bears watching.

Well, I would recommend PULLING, not watching. You may have a shorting
coil ot other problem. Often, there are visual indications. I would
rather find out on the bench than during takeoff. Also check the wire
going to the ignition switch. This wire grounds the mag when the switch
is in the "off" position. If it is shorting somewhere else, this can
also cause your condition.

The probability of a mag problem is pretty high. The probability of all
4 bottom plugs fouling completely at the same time is pretty low, unless
you are burning 2 quarts an hour.

Good Luck,
Mike