The Cessna 120-140 Association Forum

Does anyone run ethanol free gas (87 octane)? If so, do you like it? Any pireps? Good / bad?

4390 wrote: ↑Sat Jun 08, 2019 10:48 am Does anyone run ethanol free gas (87 octane)? If so, do you like it? Any pireps? Good / bad?

Yes, and have since the EAA STC was issued "many" years ago. I do use 100LL probably every other fill-up & often end up with a blend. With pure auto fuel I notice a difference in idle (...believe the STC mentions this) as well as on start-up in cold weather...plus the auto fuel stinks . I've never realized any issues with abnormal wear of any kind. My home field has no fuel so it's a nice "convenience" to be able add "car gas" when I need to. I use ethanol-free fuel exclusively in my lawn mowers, too, incidentally. I never fuel the plane in the hangar and do my best to use a non-conductive funnel and to minimize the risk of static spark. Mac

I run it frequently. 100LL has more lead in it than Continental recommends. I probably average 75% mogas 25% 100LL. No issues to report. I have a
neoprene needle valve in my Stromberg carb and am aware of possible issues ( viewtopic.php?f=10&t=100 ) but have not experienced any problems, yet. I check my gas for ethanol, each time I buy it.

Only, about, 6000 hours on auto gas so far.

6298 wrote: ↑Sat Jun 08, 2019 7:10 pm Only, about, 6000 hours on auto gas so far.

Let us know how it works out after you get some more experience under your belt...

Well, I tried some Ethanol free gas and it seems to run just fine at full and cruise power but stumbles quite a bit from idles speeds to power, even quit a few times. Like the idle mixture is too lean now. Do I have to adjust the carb to run this gas?

4390 wrote: ↑Sun Jun 23, 2019 2:33 pm Well, I tried some Ethanol free gas and it seems to run just fine at full and cruise power but stumbles quite a bit from idles speeds to power, even quit a few times. Like the idle mixture is too lean now. Do I have to adjust the carb to run this gas?

I've so carefully filed my (EAA) STC that I can't put my hands on it right now...but, as I recall, there's mention that the "conversion" to using auto fuel may prompt need for idle mixture adjustment. Mac

2066 wrote: ↑Sun Jun 23, 2019 6:09 pm

4390 wrote: ↑Sun Jun 23, 2019 2:33 pm Well, I tried some Ethanol free gas and it seems to run just fine at full and cruise power but stumbles quite a bit from idles speeds to power, even quit a few times. Like the idle mixture is too lean now. Do I have to adjust the carb to run this gas?

I've so carefully filed my (EAA) STC that I can't put my hands on it right now...but, as I recall, there's mention that the "conversion" to using auto fuel may prompt need for idle mixture adjustment. Mac

...found it (The EAA STC "Flight Manual Supplement" in the 140 right where it's supposed to be ): "...If the engine tends to stop while gliding with a closed throttle, the idling mixture should be readjusted. If the engine stops when the throttle is opened suddenly, return the throttle to the closed position and open slowly or operate the primer for one or two strokes." I don't recall ever having any of those issues, even with 100% auto fuel but, again, I normally fly with a 100LL/ethanol-free auto fuel "mix"...been utilizing the STC since 1985. Mac