I am noticing some problems using 100LL,
I for one will be really happy when that stuff
goes away. It doesn't even have to go away,
just wish more places had 80 or mogas.
--
Perry Mick
Perry, just out of curiosity what problems are you encountring using
100LL.
I have approx 160 hours using the stuff and have not noticed any
problems
(yet).
Ed Anderson
It is similar to the effect of your plugs starting to go bad. Basically
it's the same thing, fouled plugs.
I never burn 100LL when I'm just flying around the home base, so
never see the problem then. I noticed it on my return flight from
Kansas last July, and again on my return flight from Phoenix on
Sunday.
When the engine is cold, first flight of the day, don't notice a
problem. The problem seems to show when I'm taking off with
a warm engine, after a fuel stop. During the climbout the engine
will loose power, which gets my attention. RPM drops about 200
RPM, no big deal, still able to climb. So I stay close to the airport
while climbing out. My theory is it's running only on the trailing
plugs and the leadings are fouled. Oil and water temps quickly
rise 20 degrees higher than normal, probably due to the delayed
timing on the trailing plugs. I throttle back slightly to around 4500
for about 30 seconds, then slowly put the throttle back to full.
Then it recovers, and the temps return to normal amazingly fast.
That is it, everything is normal for the rest of the flight.
A neighbor flying a Midget Mustang with an antique engine, mixes
autogas with his 100LL to reduce spark plug fouling, on the advise
of other antique engine fliers. He says antique engine guys have to
lean way back to avoid spark plug fouling. So you and Tracy
probably have no problems because you can lean your engines.
I'm just going to try harder in the future to make fuel stops at
places that have Mogas or 80.
--
Perry Mick
Duckt N7XR
Ok, thanks, Perry. Yes, my plugs tend to start showing the effects of lead
fouling (from examining the plugs that is what it appears to be) after about
25 hours of 100LL. This causes the SAG (Sparkplug Attention Getter) that I,
Tracy and now you have experienced. Same conditions, high power setting
after takeoff (when you really want all the power you can get) and the
engine drops 150-200 rpm AGgg! So far I 've just stuck in new plugs, but I
may try cleaning some of the plugs using local airport aircraft sparkplug
cleaner just to see if it helps.
Ed Anderson
I know Tracy is against this but he is a bit closed minded sometimes :-)
IMHO you guys ought to try multiple spark capacitor discharge ignition systems.
MSD for short. It is well proven to punch through spark plug deposits
for years. I built my first CD system back in the 60's using vacuum tubes
and mechanical vibrators for voltage conversion. Worked great
then as it will work great now.
You can use the tach pulse from the inductive pickup to fire
the CD multiple times. You can use Tracy ignition pulse for
the Chevy coils with an AND gate to fire the CD multiple times.
If you want to build your own I have several schematics.
Paul Lamar
Not sure which part of this Tracy is against, but if you look at the chart closly you will see
that the spark duration on the CD is short. The longer the duration of the spark the more fuel is
heated in a given period of time and the more complete combustion for the cycle. This produces
more power, reduces emissions, and gives better fuel consumption.
Royce
The facts are the dyno runs disprove this theory. You get more power
and less fuel burn with CD's. Even with the short single spark let alone
the multiple sparks. The big negative issue for cars is higher cost.
Almost nobody goes racing now adays with out CD's.
Paul Lamar
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