Auto fuel

[albalone]

I'd like to hear about experiences with auto fuel in carbureted RVs. I'm in California and our auto fuel typically has 3 to 6% alcohol. I've been flying an O-200 powered Midget Mustang I built for 20 years. It's not an RV but it is metal and I hope you'll share your experience with me. I stuck a valve in my O-200 after a steady diet of 100LL, ran auto for years, then quit when the gasohol showed up. An RV friend said you guys have tons of experience with auto and to post here. What have you found out?

[turbo]

do a search for auto fuel and read away. lots of stored info. i burn quite a bit myself. i saved a lot for my engine replacement funds.

[todehnal]

I have two airplanes with the same engine parts as your 0-200. I have a Cub with a C-90 and a C-170 with a C-145, both are run exclusively on auto gas. I do add 2 ounces of pure synthetic 2 cycle oil to each 5 gal as a top cyl lube and have been doing so for over 6 years and almost 800 hr. I test every load for alcohol. Why?

The rest of the story: I, accidentally picked up a batch of E10 and was running it in both engines. The 170 did fine. The Cub developed a habit that it would quit as I got up to about 200 feet off the runway. Not Fun! It took three times before I figured out the problem. After dismantling the carb. I found the the neoprene tipped needle valve had swollen slightly and was limiting the fuel flow to the bowl and could not support full power fuel requirements. A rebuild with a stainless steel needle valve solved the problem, but I still insist on no alcohol in my fuel.

Hope this helps
Tom

[frankh]

200 hours on straight mogas and about 100 or so on Ethanol.

Fule injected with wingroot pumps and no mechanical pump.

So far no issues although E10 won't lean out quite as far running lean of peak as 100LL or straight mogas will.

Frank

[AZtailwind]

FWIW: One 182 up here has more than 6,000 hours of Mogas. (That is 3 0470 overhauls of two engines) I have 500 hours of Mogas in our 182 without problems. Many of our groups 182 have truck tanks and have run into few problems. We have been seeing ethanol creep into many stations up in N. AZ. latley though
But we still have one station that is ethanol free....our carberated RV6A has about 90 hours of Mogas but we run 1/2 Mogas 91 oct, 1/2 100LL, I have noted that hot starts with mogas is slightly harder with the Mogas/avgas combo. But after the cooler gas flows through the engine driven fuel pump- engine idle does return to normal

[guccidude1]

Here in Washoe County (Reno) NV, 10% ethanol is added during the winter months for air quality. I use 91 RON in my 0-360 RV-9A year around and have not seen any adversed effects in 265 hours, 19 months. Prior to that, I used CA 87 RON gas with MTBE, then ethanol oxigenatiors for 10 years then four years here in Reno in my 1976 C-182P with 40 gallon bladder tanks. No difficulties noted on either aircraft, summer or winter with summer DAs at 7500 to 8000" and winter temperatures at 20F. Dan.

[mannanj]

Originally Posted by todehnal

The rest of the story: I, accidentally picked up a batch of E10 and was running it in both engines. The 170 did fine. The Cub developed a habit that it would quit as I got up to about 200 feet off the runway. Not Fun! It took three times before I figured out the problem. After dismantling the carb. I found the the neoprene tipped needle valve had swollen slightly and was limiting the fuel flow to the bowl and could not support full power fuel requirements. A rebuild with a stainless steel needle valve solved the problem, but I still insist on no alcohol in my fuel.

Hope this helps
Tom

Any one with a small Continental using the NAS-3A Stromberg carb (or any carburator) with a neoprene tipped needle valve should change it to an all metal one if you are going to use auto fuel.

This happened to me in the 80's when a friend did me a "favor" and bought premium auto fuel for my Champ with a 65hp engine. The oxygenator in the premium fuel did a number on the neoprene tip just like the above post, only my engine quit about 50 ft above the runway. Using my usual 3 brain cells, I thougt I would try it again. Same thing.

What happens is that the swelled needle tip pushes the needle away from the seat, which causes the float to drop, which causes the level of fuel in the float chamber to drop below where the main jet can get sufficient fuel in a climb attitude. This causes the engine to sputter and die, which causes extreme consternation to the pilot, leading to profuse sweating, (sometimes, wetting of the pants), and other problems.

This isn't a problem with other carburators not using the neoprene tipped needle/seat combination.

[pierre smith]

....but is there any way to know whether you have a teflon-tipped needle or not? We had our MA-4 rebuilt by Precision in 2005, the year we first flew. Although I use some mogas without alky, I'd like to know. I assume that I'd have to drop the float bowl to be sure.

Thanks

[mannanj]

Pierre:

AFAIK, the Stromberg NAS-3A1 was the only one that used the neoprene tip.

Hopefully someone here will know for sure.