auto gas / A-65

[robbie]

Any one out there having this problem with auto gas.
Cold weather (below 50) the engine loads up when idleing.
When I do a run up, it stumples and blow black smoke until the RMP's get up to 1200 or so then it fine.
After the engine is warmed, no problems.
In the summer it's ok.

[Goneflyin]

Robbie, just the opposite of mine. In cold weather mine goes lean, I usually have to use the primer as a accelerator pump to get it off idle. How's it with 100LL in the cold? Does it clean up after it warms up?

Bill

[crispy critter]

Auto Gas and weather change.

Guys,it sounds to me like you have the old stromburg carb(with no accelorator pump).They are very tempermental to tempature/weather change.It really doesn't have much to do with your gas(these old engines were made to run on 70-80 oct and no more).The reason you guys are having the same trouble during opposite seasons is because of the way(or season)your carb was last tuned too.If you could add a mixture control or upgrade to a M&S carb I would almost bet the farm that by doing the switch would solve all your troubles.

However if this is the first time it has acted up on you I would first try cleaning or replacing the spark plugs,but if it is something that's reoccuring then the difference in season is causing a mixture change.

Hope this helps.

[robbie]

Bill ,
I need to give her a few shots of primer if its really cold to keep it running also, it loads up when the rpm's get above the idle speed section of the carb and into the fix jetting of the carb like 1000-1200 RPM's
Kevin,
You might be on to something, on 100LL (can't get 80 here)
It really doesn't load up or very little. Like it barks and it right up to 1500 rpms for the mags check.

[alwaysoar]

Just to echo what Robbie said, I had the exact problem. It was especially bad when I had the cowl off in cold weather to do a test run after installing a new exhaust. When I put the cowl back on and gave it a chance to warm up, it ran great.

The question I have now has to do with auto gas. I've been using Mobile 93 hoping that would eliminate carbon build up (I'm now starting to use MMM). What auto fuel is best?

Ed@BTV VT
TF 527

[crispy critter]

Auto Gas

We always use BP 87 oct. which is owned or distributed by Ashland Oil here in east Ky.
I have the same problem with my Smith Mini.It is flown very little in cool weather because it is open cockpit but I do fly it once in a while throught the winter just loosen it up.My Smith has the C-65 that came off Crispy Critter.I tuned it up in warm weather and it runs fine in warm weather but has the same problems in cool weather as you guys do.
I also had a T-craft with a 65 that was the same way.I would re-tune it in the spring and fall and it always ran fine.The gas had nothing to do with it.I tried 100LL a time or two when cool weather started and it helped a little bit but still hesitated when cold and fine when warm.
If you don't have the accelerator pump in your carb then you will have this problem when the seasons change.
If your hesitation happens every year when the seasons change then that is the problem but it you have never had it then you might want to check your plugs or lead wires.

How about that Dale Jr. today in the Daytona 500,I'm so proud

[d.a.]

I don't know about the Auto Gas in other states, but here in California the Auto Gas is significantly different than Aviation fuel. I used to run Auto Gas in my 600 horse Ag Cat to save money. It immediately ran poorly when cold. It was very hard to keep running and I usually had to taxi out to the run up area with the primer out to keep it running. As soon I would go back to Avgas, it immediately ran great when cold, quick throttle response, ran smooth, etc.. Also, Auto gas vaporizes differently than Avgas. Take a closed can of Avgas a shake it and nothing will happen. Shake that same can with Auto gas and it will pressurize the can. Many people have had vapor lock problems with their aircraft when they use Auto gas at high altitudes. Plus, there's something in Auto gas that will attack resins and plastics when Avgas won't. A friend of mine had his carb gum up. He finally figured out that the Auto gas desolved the schelac off of his gas gauge cork. Pour Avgas into a styrofoam cup, nothing happens. Pour Auto gas into that same cup and the bottom will desolve before you get the cup filled. Don't get me wrong, even with all this personal experience, I'll still run Auto gas, but believe me---it's not the same as Avgas.
Dave

[Goneflyin]

Robbie, the richness your experincing may be from it be over primed when it's cold. I do the same thing sometimes, the engine can be a bugger to keep running even after preheating. I've started mine brought it up to a 1000 rpm to warm up and I see black exhaust coming out against the snow and kinda 8 stroking. Once it warms up a little and blow it out it cleans up a little. If thats similar to yours I'm not sure what the fix is, I've tried adjusting the idle, starting with carb heat on and a few other tricks I can't think of now. There have been lots of discussions on atomization characteristics of auto and av gas, I've been adding a gallon or 2 of av gas to a tank of auto fuel (87) and it seems to help and I've also had less valve problems. Also try not to load it up to much as that extra gas washes the oil off the cylinder wall on those cold mornings.

Bill

[Pearson]

Auto Gas

Concerning the use of auto gas in the A-65 Continental engine, I have used it for the last three years with only minor problems. One of the problems I had was running rich and fouling the plugs. This would occur during the cold season only. First I checked the float level and readjusted accordingly, using the washers under the needle and seat assembly. That helped with the fuel dripping when I turned the prop through to prime it (I don't have the plunger type primer). But the thing that eventually cured my problem was to just readjust the mixture every spring and fall. With spring rapidly approaching, I will just reach in and turn the little thumb screw out about 1/4 to 3/8 of a turn when the weather starts warming up. I have done this for the last two years and it works on my airplane.

[crispy critter]

Auto Gas

Richard,
I do the same thing and it works like a charm...every season.

[jrzangger]

I've had my carb apart three times since it was overhauled and no significant change. It drips if I don't shut the gas off and runs very rich until warmed up. A little prime of course when cold. As soon as it gets up on the main jet it smooths right out and usually doesn't offer any more problems. Is worse in colder weather like yours. I've just learned to live with the Bendix Stomberg's peculularities! If you can add a little rpm every thirty seconds or so after start up it seems you can by pass the loading up.

Tell me why, in over 850 hours, I've never had carburater ice with this engine. I've checked a number of times and have not had it yet. Other 65's seemed prone to it, but whatever it is, this engine doesn't let it form.