TESTING has been most interesting.
A week ago, after laborious ground runs, rapid throttle movements, etc, a
first flight was made with very positive results - smooth engine, good power,
and all numbers in the normal range. A mere 20 min flight checkout over
the airport.
The second flight was not as pleasant because of burbling at low rpm
and consistent misfire at cruise........ I say consistent because no temperature
indicated any troublesome cylinder. What gives?
I started out with the fancy ($10) moped plugs (triple electrode,
W27EBR-C) that I didn't like because of the inconsistent gapping (around .040)
and 24 adjustment prongs that proved difficult to adjust. The plugs
were pulled and cleaned with nothing more than a momentary improvement.
Maybe the gaps were too large?
I had a chat with Klaus and he asked if I had set the idle mixture
- "No, I had an electronic ignition (LASAR) and that is was
OK." He insisted that I check it and so that was done. The
final settings were very close to those previously set. High RPM run ups
were done with leaning trying to self-clean the plugs and a short flight was
accomplished with engine coarseness and frequent misfire at idle after
returning.
Klaus also mentioned some other items that new installers should take
note:
1. The wires exiting the sensors should be supported by something that
shakes in sync with the sensors (engine) so that the plug pin vibration is kept
to a minimum. He suggested an adel clamp to one of the screws
that fasten on the sensor back plate. There is a small problem
in that the screw cannot be too long because it would hit the case fins.
This procedure would have been easy to do if it had been done before the sensors
were installed. However, I did find nearby spots on the engine to secure
these wires rather than the 4 or 5 inch to the wire bundle that travels behind
the engine. A better design would have been to put the connectors on
a 10-12 inch pigtails coming out of the sensors. Then, the connection
could have been isolated from vibration away from the engine. I will pass
this along to Klaus as a suggestion.
2. Along with item 1, I noted to Klaus that the connector screws had
worked themselves loose. He said some users had wrapped the connector
with a tie wrap just behind the screws to keep them from backing out.
OK, I did that too. Note that the pigtail type connection solves that
problem also.
Since I still had a rough idle, I replaced the upper plugs with the cheaper
W27EMR-C and more consistent gaps. Operation on the upper ignition was
smoother so I went for another short flight. Upon return, the mis-firing
was again occurring on both. In the meantime, I had ordered a batch of
W27EMR-Cs and a set of the Iridium Denso IK7s.
With time on my hands, I wondered how plugs could be fouled so fast, even
if the idle mixture was rich (leaned during taxi) it seemed unlikely that the
plugs would become unusable in such a short time.
What could be different? I had a friend helping with the adapter/plug
install and, following LSE directions, an anti-seize was used. He had
grabbed the Permatex silvery-toothpaste stuff used with the exhaust slip
crossover connections. I looked at the back where it listed plugs as
one of the applications and so it was used. But now, in light of the
fouling problems, there was some concern because this stuff doesn't go away
(rated to 1600F) and becomes quite liquid at high temp, leaving behind a
silver-like residue - no wonder it works so well on the exhaust system.
Could this residue be migrating to the plug ends and contributing their becoming
fouled? I have always used the black Champion plug anti-seize before
this and never had a problem. The friend has the Electroair system and had
switched to aviation plugs because of fouling - he even fouled fine-wire plugs
and always uses the Permatex. Hmmmmmm......
Yesterday, I removed the adapters and plugs, cleaned the adapters and the
engine helicoils as best I could with acetone and installed them along with the
new IK7s using the Champion anti-seize. Run ups went well and the
forty minute flight was a smooth as the first. Post flight taxi and idle
remained smooth. Of course, at least another flight will be necessary to
see if the Permatex was at fault and I hope there is no Permatex residue hanging
around.
BTW, I like the IK7 plugs because the gap is consistently between .030 and
something less than .035.
For those still interested, here are some flight details.
I took off and climbed directly to 7500 MSL at 135 KIAS - my usual.
What was different is the trimmed attitude didn't require any adjustment all the
way up - a first.
7500 MSL, 30.03 Baro, 17C, WOT, 24" MAP, 2510 RPM, 172 IAS, 195 KTAS, 25.9L
and 25.1R timing.
Lean operation: #1 peaked at 1390, 8.7 GPH, then enriched 100F, 9.8
GPH:
CYL CHT EGT
1 370 1290
2 380 1310
3 370 1290
4 390 1310
For Speed Demon, Hurry Up Larry, et al,
I descended to 2000 MSL and stabilized level with WOT, 29.6" MAP, 2700 RPM,
Cyl #1 CHT 350, about 13.5 or so GPH, 20 degrees BTDC
204 KIAS, 211 KTAS
That's the fastest I can remember! Hmmmmm... I might have to
re-adjust the nose-down trim spring or the flap reflex...... I would have liked
to provide more data, but flying was more important than writing.
One last "gripe". The dual LSE units are interconnected so that if a
timing sensor fails, the other can take over (and the timing curve is altered, I
believe). It is very difficult to exactly align the sensors and 1 degree
of arc is only 67 microseconds at 2500 rpm - about .02" of piston movement
- but, timing is important! So, I will ask Klaus the effect of switching
off one sensor so that both ignitions use the same timing or why a switch can't
be provided that would have both ignitions use the same sensor (ergo exactly the
same timing) but switch to the other if there is a failure. Hmmmm,
maybe I will have to hook up the timing pots.
I will report more data as testing continues.