• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

O-360 Marvin-Schebler Autofuel.

jokerswe2008

Registered User
Hello,
I am planning to use auto fuel in my O-360 PA18. Does anyone have experience with that? I have the required hoses.. and above 500 ft I get vertigo so vapour locks should not be an issue...Does anyone have experience with the auto fuel?
 
Hello,
I am planning to use auto fuel in my O-360 PA18. Does anyone have experience with that? I have the required hoses.. and above 500 ft I get vertigo so vapour locks should not be an issue...Does anyone have experience with the auto fuel?

Not an o360 but I have burned over 20,000 gls of efree in little Continentals

Glenn
 
the O-360 is approved for autofuel- so I’m most concerned about the carburetor. Does the continentals also use Marvin Scheblers?!


Nearby flight instructor has run two Cessna 150s for years and hundreds and hundreds of hours on auto gas. The O200-A engines use M-S carburetors. Has not been a problem for him.
 
Ran 92UL in an O-360 PA-12 when needed in summer. Did ok but preferred 20-25% 100LL if I could get it mixed. I think auto fuel contains more water and had some issues with ice crystals so ran 100LL in winter if available.

Gary
 
I ran super un- leaded in a 0-360A1A in a Starduster Too without any problems in the 200+ hours we had it
 
You will be all right. I have an O-320 with MS carb no problem after couple thousand hours. I run mostly ethanol laced 89 straight from the pump. Just watch your engine temperatures and don't expect 100LL performance. If you are not flying often keep a bit of avgas in second tank (if you have one) and before engine shutdown "fill the fuel system" with avgas.
 
I believe on the o-360 you must use premium, however these days it is about the only ethanol free fuel you can get in the states.
 
From the Peterson Auto Fuel STC website:

"Approved Engines & Airframes
Auto Fuel STCs are approved on 48 different engine types and 100+ airframes including nearly all 80/87 octane engines and the majority of airplanes in which these engines were installed. Several high compression engines are also approved for the use of 91AKI auto fuel including the 180 horsepower 0- 360 and the 115hp (or less) 0-235-L2C. "
 
The carburetor float level should be set for the specific gravity of the auto gas, as it's different than the specific gravity of av gas. The carburetor manual will tell you the specifics.
John
 
The carburetor float level should be set for the specific gravity of the auto gas, as it's different than the specific gravity of av gas. The carburetor manual will tell you the specifics.
John

I have switched back and forth on 5 different aircraft and never notice any difference in performance.

Glenn
 
I believe on the o-360 you must use premium, however these days it is about the only ethanol free fuel you can get in the states.

I've used 87 octane unleaded e-zero mogas in my airplanes for years,
from the local Cenex aka Co-op farm stores.
I've burned over 3000 hours worth of that fuel in O200's, O300's, O320's, and O470's--
mainly mixed with 20-25% 100LL.
No problems with MS carb, or anything else.
 
If your fuel tank has any sloshing compound or other seam sealer, you want to be careful. I have been running 3/4 auto for maybe 40 years, but won't put it in my wing tank for that reason.

It could be better now; stuff like MTBE is no longer allowed in auto gas.

A lot of folks tell me modern auto gas is bad for Cubs, and even old cars, but I don't seem to have any problem going well beyond TBO.
 
Back and forth between Avgas and 90 octane Mogas in my 160 HP doesn't seem to make any difference in performance. Digital tach, with 10 RPM resolution.

Didn't change anything with the carb when converting from 150 HP. Best power (sea level) is with the mixture pulled out about an inch.
 
Last edited:
I burn almost all e-free mo gas but don't let is sit. Mo gas goes bad long before 100LL and mucks things up.
 
Does autogas help with lead-fouling? I get some fouling on the bottom plus, even though I lean on the ground.

Yes being there is no lead in the fuel. My experience is that it is rare to have valves sticking in the guides as well.
In general any of the lower compression engines that were not originally rated for 100Oct fuel is better off on autogas.
Obviously opinions vary.
 
Yes being there is no lead in the fuel. My experience is that it is rare to have valves sticking in the guides as well.
In general any of the lower compression engines that were not originally rated for 100Oct fuel is better off on autogas.
Obviously opinions vary.
When we where "fish spotting" back in the 90's, our boats brought us "car gas" to burn in our Cubs.
Most of us found that a steady diet of straight "unleaded" regular auto fuel in
0320 engines will most certainly result
in valves starting to "drag" in the guides. If you persisted the valve timing would get so far off the ignition timing they would start to sound like a
"Patridge drumming up on the ridge"[emoji15]
All that was easily cured by adding 1 quart of Marvel Mystery Oil to 55gals of auto fuel. Never experenced ANY problems with auto fuel as long as it had the MMO as an additive!
Pretty common to go through 30/40 drums of fuel every season .
The MMO most certainly effects the valve stems relationship to the guides.
Of course blending in a small amount of lead via AV gas is also an excellent
choice, and we found that as little as 10% was sufficient for valve lubrication! Your mileage will likely vary.............[emoji6]

Sent from my LM-X210 using SuperCub.Org mobile app
 
Sjohnson,
I am guessing a good way to answer that question is NO a little bit of auto
fuel will not cure your leading problems in your lower plugs........
Straight auto fuel will cure that problem. But with out MMO it can cause other
problems, a lot of guys think that 100LL is actually low in lead; however that
may be true compared to 130, but I think it's way more than the original 80/87
these old engines were designed for.
Possibly Pete can comment on this to clear it up even better?
What say you Sky8A???
E
 
Sjohnson,
I am guessing a good way to answer that question is NO a little bit of auto
fuel will not cure your leading problems in your lower plugs........
Straight auto fuel will cure that problem. But with out MMO it can cause other
problems, a lot of guys think that 100LL is actually low in lead; however that
may be true compared to 130, but I think it's way more than the original 80/87
these old engines were designed for.
Possibly Pete can comment on this to clear it up even better?
What say you Sky8A???
E

100LL has 5 times the lead that 80 had

Glenn
 
They call it 100LL since there previously had been a higher lead content in 100 oct fuels not to mention the even higher octane fuels developed in the '30s & 40s.
Today's unleaded fuels are pretty good as long as the ethanol is kept in a separate glass.
And yes Marval Mystery oil is good stuff, less needed in little Continentals than Lycomings.
Lycoming engines do better with more oil flow to the valve cover especially the exhaust valve.
 
Tnx Glenn, could not remember how much more lead was in 100, but knew it was huge!
So that should clear up any concerns on plug fouling, your running "5 times" what the engine
was designed to deal with when you run straight 100LL. So if the math is correct, running 50%
auto fuel/ 50% 100LL Av gas. Your still 2.5 times what 80 had in it ???
 
I'll try. The following contains a table of aviation fuel grades: https://en.wikipedia.org/wiki/Avgas
Notice that 80/87 oct contains 0.14 g/l of lead. 100LL contains 0.56 g/l of lead. and 100/130 contains 1.12 g/l of lead which was double that of the current 100LL. AND the current 100LL contains 4 times the amount of lead as the old 80/87 oct.

sjohnson, Since you are fouling just your bottom plugs it appears that you should increase the heat range of your bottom plugs. Search on line for a spark plug chart for the information for your brand of plug.
This has some information which you may find informative. http://www.imps4ever.info/tech/engine/sparking-plugs-spark-plugs/spark-plugs.html " A hot running plug has a much slower rate of heat transfer and is used to avoid fouling where combustion chamber or cylinder head temperatures are relatively low."
 
Over 500 hours on my O-360-A1A with probably 90% mogas 91E0. No issues ever. Clean plugs. I only run avgas on cross country when no other choice.
 
Back
Top