Auto fuel & valve seats etc

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JackC

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I have been running a mix of non ethanol 92oct auto fuel and also 100ll based on where I land and need fuel, back at base it’s often auto fuel and going other places it’s often 100ll based on availability

Question, have A65s had issue only running auto fuel with the valves or anything?
 
Great question. I also run 91 non oxygenated fuel in my A65. Im also interested with this question. I've always thought that 100LL caused more issues but maybe someone can educate me.
 
I have had great luck with auto regular, giving the engine a shot of 100LL maybe every fifth or sixth tank full. But that is on C-85s.

The engines were designed for 73 octane. The lead in 100LL is about four times that of old 80/87.

I fly these engines about 150 hours/year - daily flights - so suspect that is part of the equation. I would never admit to using a little MMO, since it is not approved for aircraft.
 
I wouldn't have any concerns about running clean gas in an A65 especially if you're using 100LL occasionally. They're "officially" an 80oct engine but were designed to run on 73oct as were the Continental W670 and some of the other WWII trainer engines. ("Jeep Gas")

I used 87 clean gas in my O-320 for 10+ years. The only difference noticeable was that the spark plugs, piston tops, and valves were perfectly clean at annuals. The engine made 2400 hours before the cam failed but the valves looked fine upon disassembly for overhaul. I would switch back to it immediately if it was available in this state. (Locally, car gas with ethanol is $3.65 vs $6.95 for 100LL.)

Mike Busch reported in an article that his company was monitoring several C182s running on clean fuel and they were aware of no problems as a result of that.
 
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I am also running my Lycoming O-235-C1 on 87, non-alcohol, auto fuel. There just happens to be a gas station right by the airport with ethanol free gasoline (approximately $2.90 per gallon). My annual is next month so I'm wondering how things will look as I've not used any 100LL since last annual. I have read that 100LL is the cause of sticking valves and fouled plugs. Then again, I had read that some Continentals had experienced accelerated valve seat wear. I guess I'll learn more once the aircraft is into the annual.
 
if you have a old Stromberg carb, you might want to stick with 100LL or at least check to see what the tip of the needle is Made of. If it’s delrin, car gas might be an issue. I had a partial power failure that we traced to fuel flow. Called the shop that overhauled the carb and he (old guy- older than me even- always listen to the old guy)immediately asked what I was using for fuel. I said 93 ethanol free. After he got done reaming me out and telling me to go back to 100LL he said there is an additive in car gas that will swell that tip And if I switch back to 100LL it will fix itself. He was right.

Food for thought,

Pete
 
That happened to me many years ago with my A65-powered Chief. One cold winter, I stupidly put a can of gasoline deicer ("Heet") in the tank due to concern about water freezing in the fuel system.

Run-up was normal but the engine was cutting out on takeoff so it was an abort. Checking the carburetor found the rubber tip on the float needle swelled up to the size of a pea. It turned out that Heet is mostly alcohol. The new float needle had a plastic tip.

It was just another case of surviving a screw-up and learning something from it.
 
Concerning auto fuel, it's important to test each batch.

I found 5% alcohol at the pump once before filling my portable tank. Had to do the test again for the station manager as he initially didn't believe me.

It's easy to drain a bit out of the hose for the test without starting the pump. EAA sells a simple test kit for a few bucks.
 
My mechanic went nuts on me for running alcohol free gas.Told me the new gases start going bad in 30 days,told me to stick with 100LL,I'm running A65 in my Champ
 
If you hold the STC, you can do what you want. It is true that car gas deteriorates quicker than avgas - you can see it is a really serious problem by observing all those cars abandoned on the side of the road.

My 1965 Mustang Convertible developed an intermittent problem - it was the fuel pump, but it took me four years to diagnose it. Once I fixed the pump, it ran ok on four year old auto gas. I threw a couple gallons of 100LL in the tank after I got it running just to make sure.

All that aside, if you only fly once a month, definitely stick to avgas. Your mechanic is giving you good advice.
 
I heard the big issue was the valve seat wear

interesting about the carb…

as far as time goes if I have auto fuel it’s getting burned off pretty quick, for winter storage 100ll seems a wise idea
 
Bob Turner said:
If you hold the STC, you can do what you want. It is true that car gas deteriorates quicker than avgas - you can see it is a really serious problem by observing all those cars abandoned on the side of the road.

My 1965 Mustang Convertible developed an intermittent problem - it was the fuel pump, but it took me four years to diagnose it. Once I fixed the pump, it ran ok on four year old auto gas. I threw a couple gallons of 100LL in the tank after I got it running just to make sure.

All that aside, if you only fly once a month, definitely stick to avgas. Your mechanic is giving you good advice.
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I have the STC but the problem was like you mentioned I wasn't able to fly enough,so I drained all the auto gas (alcohol free) took it home for the lawn mowers and dumped 10 gals of 100LL in the Champ.PS:I had the same problem with my 1960 Corvette,fuel pump,pinhole in the diapharm
 
Yeah. We used to be able to buy kits and rebuild them - no more. You buy a sealed unit. Boo.

That much lead does not seem to be all that good for low compression engines, but we are burning it exclusively in the 220 Stearman with no problems at all. I would never, of course, recommend anything like MMO or a lead scavenging additive. Not approved.
 
100LL plus TCP seems to work pretty well in an A65 that is flown frequently. If I had better access to ethanol free 93, I would probably mix it 50:50 with 100LL.
 
Pburns said:
if you have a old Stromberg carb, you might want to stick with 100LL or at least check to see what the tip of the needle is Made of. If it’s delrin, car gas might be an issue. I had a partial power failure that we traced to fuel flow. Called the shop that overhauled the carb and he (old guy- older than me even- always listen to the old guy)immediately asked what I was using for fuel. I said 93 ethanol free. After he got done reaming me out and telling me to go back to 100LL he said there is an additive in car gas that will swell that tip And if I switch back to 100LL it will fix itself. He was right.

Food for thought,

Pete
Click to expand...
Pete and the collective bunch, Can you elaborate on this at all? I recently switched from 100LL to a 50/50 blend with 89 ethanol free... I notice that cold start is so much better with the blended fuel, but... i'm getting more fuel seepage in the Stromberg than I was before... like a streak of green on the lower cowling. I cant help but think this is related to what you were saying about the tip of the needle swelling up.
 
That's pretty much all I got from him. I have no idea what he thought the additive was, but when I switched back to 100LL problem solved. It makes sense from a mechanical point of view based on symptoms and cure. Swelled tip, less fuel, partial power loss. I was on climb out about 1/2 mile from the strip when I lost almost 200rpm. Duplicated it on the ground so it wasn't carb ice. That was almost 300 hours ago with no issues since.
Might seem far fetched, but I have a friend with a Cub that swears the different specific gravity between mogas and avgas messes up his carb due to the difference in float height. Possibly something to consider when peering into a rabbit hole...

Pete
 
Pburns said:
That's pretty much all I got from him. I have no idea what he thought the additive was, but when I switched back to 100LL problem solved. It makes sense from a mechanical point of view based on symptoms and cure. Swelled tip, less fuel, partial power loss. I was on climb out about 1/2 mile from the strip when I lost almost 200rpm. Duplicated it on the ground so it wasn't carb ice. That was almost 300 hours ago with no issues since.
Might seem far fetched, but I have a friend with a Cub that swears the different specific gravity between mogas and avgas messes up his carb due to the difference in float height. Possibly something to consider when peering into a rabbit hole...

Pete
Click to expand...

200rpm loss would have be replacing stuff, just going to mogas should not do that in a healthy engine
 
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