It is now official. I am now the proud owner of my first aircraft, a beautiful 1954 C-170B, N2734C All the rudder cable and pulley work is finished and I will be picking it up from Headland Alabama and making for Northern VA via a side trip to visit Dad in Memphis.
Since the aircraft has an STC for autogas, and price of 100LL is $2.60 at Front Royal VA I am going the autogas route. Question is what brand of autogas to use. I know not to use fuel with alchohol (sp)?, but the STC does not say how to test for the presence of alchohol. What major brands of 87 octance autogas do not have alchohol
If auto gas contains alcohol or not depends more on the area of the country or state rather than the brand of the gas. In states that do have alcohol in the gas I think they are required to post it on the pump. Here in Georga there is no alcohol in the gas. However in the Atlanta area they do have the reformulated gas which I have been told is not as good as the gas sold in other areas of the state. I use some auto gas and some 100 ll av gas locally and av gas when fueling away from home and occassionally 80 octane av gas whenever I can find it (Moontown is the only place I know of in Alabama with 80 octane)..Just my two cents worth.
I wish I had kept an article I read a couple years ago on how to test for alcohol, but here's the gist of it:
Select a sample of fuel in a clean container (sounds like a Mason-jar to me), but first place a known quantity of water in it (mark the level of water before adding the fuel), close it up and shake it vigorously. Without opening it, let it settle completely. If the water level appears to rise, then the fuel has alcohol in it. (Alcohol and water have a strong affinity for each other and the water draws the alcohol out of the fuel, thereby raising the apparent level.)
You can buy a fuel tester from Sporty's, Spruce, Wagaero, etc. It can be used for fuel drain plug sampling too, comes with screw driver; I'm sure you've seen them.
They are inexpensive and this is the procedure:
1- Add water precisely to the zero level line on the % of alcohol scale
2- Add fuel to be tested up to the gas level line
3- Cap with thumb, shake vigorously to thoroughly mix
4- Let stand 5-10 minutes, read the % Alcohol-in-fuel on scale of 0-30% at line seperating gasoline and water.
Voilà !!
JD
Start quote
I wish I had kept an article I read a couple years ago on how to test for alcohol, but here's the gist of it:
Select a sample of fuel in a clean container (sounds like a Mason-jar to me), but first place a known quantity of water in it (mark the level of water before adding the fuel), close it up and shake it vigorously. Without opening it, let it settle completely. If the water level appears to rise, then the fuel has alcohol in it. (Alcohol and water have a strong affinity for each other and the water draws the alcohol out of the fuel, thereby raising the apparent level.
End Quote
If the auto fuel is an alcohol blended fuel and there is no water in the fuel your method will work.
BUT
When alcohol is present with water, the added water will return because the alcohol may be already saturated, and will not accept any more.
Now what could you really have? It could be up to 10% alcohol and not marked on the pump, and 10% water in solution. (Equil to the alcohol content) How much horse power do you think you can make with 20% of the fuel not being gas?
The thing to remember when using auto fuel is that for every 10% alcohol you lose 20% of the horse power. Want to try that on a hot day?
Think about it at full throttle in a 170 you may be making 145 horses. (maybe not) but lose 20% and you got a 116 horse 170.
You can buy a test strip at the local drug store, get them and use them, they are the only safe way to test for alcohol.
I do not believe the auto fuel with alcohol will harm your engine. The Combustion process is not the problem, the problem is all the other rubber parts in your fuel system that is effected by the BENZENE and TOLULENE in todays fuel. It attacks the resins in the rubber and hardens it until it cracks and causes leaks, "O"ring damage, ect.
Tom D. A&P-IA
John,
Congratulations on your new airplane. I've burned about 2000 gal of cargas, and this is what I've gleaned from the experience:
1. Cargas can get old and/or contaminated. To avoid this I try to buy from a newer station, brand name, that sells lots of gas. A newer station thinking that the newer storage tanks will be less vulnerable to contamination, brandname because the owners will hopefully be more quality conscience, and lots of fuel turnover means the gas is fairly fresh.
2. I do alcohol tests by using an old 16 or 20 oz plastic pop bottle. Most have a seam about 1/2 inch from the bottle. I put water in it up to the seam, then put about 3/4 full of gas. If the water/fuel interface stays at about the seam I call it good. If it moves either way substancially, it must have alcohol in it. I turn it upside-down, drain out the water and dump in the car tank.
3. I now have a card account with a station. This gives me a nice monthly report that I can use to get the state highway tax reimbursement. This was over $100 last year.
I had a long talk with a man in AL that had used autogas almost exclusively in a Cont.0300 for the life of the engine. He said he never had a problem but the problems he had heard about had to do with letting it sit for long periods with autogas in it. He also said he used only the highest octane ratings such as the 93 octane at Amoco, now BP Stations
Where I come from all autogas have at least 20% alcohol in it. I know for a fact tha apart from eating the ruber the alcohol will corode the tank, carburator, and all parts where the fuel go through. The cars have carburators and tanks coated with bras or another metal to prevent corosion.
I would love to find a way to efectively separate the alcohol from the gas, and know what would the consequences of separating be.
I checked both the EAA and the Petersen websites for the list of eligible engine for a MOGAS stc and I only see the O-300 series listed and not the earlier C-145 models. Does that make sense? If so why is the C-145 not on that list? Something different about it?!?
Hi Bruno...for all intents and purposes, the C-145 and the O-300 are the same engine. Continental changed the designation in 1955 from a number reflecting horsepower to cubic inches. Oh, early C-145s had non-dampened crankshafts, but I think around 1949 or 50 that was changed. One minor difference is the magnetos do not interchange (as I found out when my mechanic ordered O-300 mags for my C-145!) George Horn can go into more detail, if we can coax him out of his shell <grin>. Incidently, the C-145/O-300 engine holds the last four endurance flight records, the most recent being 64 days aloft (set in 1959), using inflight re-fueling. That should ease your mind at ease about reliability! It is one of the most dependable general aviation engines ever built. ..Russ Farris
IF I REMEMBER CORRECTLY, MOST OF THE STCs DESIGNATED MANUFACTURERS WHO'SE FUEL WAS ACCEPTABLE TO USE. ALL OF THEM WERE NON ALCHOLIC GAS AT THAT TIME. WHEN THE STCs WERE BEING RESEARCHED ADDITIVES WERE NOT THE NORM BUT THINGS HAVE CHANGED A LOT SINCE THEN. TOM YOU ARE GENEROUS IN THE ASSUMPTION OF HORSE POWER ON THESE OLD CONNIES, BUT SPOT ON IN ALERTING OPERATORS TO EXPECT LESS PERFORMANCE FROM MO-GAS UNDER CERTAIN CONDITIONS. OF COURSE THEY SHOULD EXPECT LESS THAN BOOK ANYWAY!
THE DAMAGE TO RUBBER PARTS IN THE FUEL SYSTEM IS A MAJOR CONCERN IN THESE OLD FUEL SYSTEMS. ANOTHER IS DE-STABILIZATION OF THE FUEL ITSELF IF STORED MORE THAN A MONTH.
Last edited by flyguy on Thu Jan 23, 2003 10:59 am, edited 1 time in total.
All the rudder cable and pulley work is finished and I will be picking it up from Headland Alabama and making for Northern VA via a side trip to visit Dad in Memphis.
I am going the autogas route. Question is what brand of autogas to use. I know not to use fuel with alchohol (sp)?, but the STC does not say how to test for the presence of alchohol. What major brands of 87 octance autogas do not have alchohol 
Thanks for checking for me..