Are there any changes to the floats or anything on a J1A5D that might be required before running mogas? I recall some floats being made from materials that mogas deteriorated and the stc for other lycomings calling for changes. Something about what the float was made out of. I'm sending my carb in for a new accelerator pump diaphragm and a inspection/cleaning and thought might as well have it updated if there was any possible upgrades.

I thought it was the compression Ratio that prevented the auto gas option not the carburetor.

J series 8.5:1 while B series which has an autogas STC 7.2:1.

I am curious on this. I know the B series are certified for 80/87 while J series is 100LL only. If there is a work around would love to hear it.

TD

There is no workaround for the certified world without paying big brother his millions.
I thought the 260hp fuel injected V4A5 model had a 91 autogas stc and was 8.5:1 pistons. I was reading about it in another post about the 91 octane V4A5 IO540. I would never run 88 octane, probably just 91 with a little avgas mixed in for good measure and pay close attention to the top of the pistons for detonation.

You are right.

The Lycoming book does show the injected V series (260 hp @2700 rpm) approved for 91/96 octane w/ a 8.5:1 compression ratio.

No difference in the floats, but several differences such as different elect boost pump, etc.. Have you checked with Maule on the STC? When running straight mogas, there is no legal mogas in the state of Alaska that I know of without alcohol in it... (with the exception of maybe some of the marina's down SE way) Also the mogas tends to eat up avgas certified packings such as on gascolator, sump drains, etc and can create quite a mess... Personally I wouldn't run the stuff as it can and does create problems. If you want to stretch your dollars some, I know of people running 50/50 mix and that seems to work pretty good under most circumstances. With all the remote country up here, I'm hesitant to run anything that could cause vapor lock, or detonation leading to engine shut down... As well as the legalities!! There's just not that much difference in price to justify being a test pilot, even though most of our engines would probably run just fine on the mogas.. I have a neighbor who blew a cylinder right off of engine with a piece of crankcase still attached caused by detonation which is hard to hear in aircraft... A lot of things besides compression enter equation on certification such as combustion chamber shape, squish band shape, valve faces, etc, etc...

My freinds old supercub fuel hoses were so swelled up and plugged with black stuff from running mogas that they don't even know how it would run. It did though.
My private pilot CFI had been a missionarry pilot in New Gini many years ago. His wife's, first husband was also, He died because the plane he was flying was running auto fuel and vapor locked.
Nowdays with the alcohol it would even be worse for both swelling or deteriorating seals and hoses, plus alcohol vapor locks worse.
Moral to the story is "Just say no to MO"

Not only that, but the Mogas goes bad MUCH quicker then Avgas, which causes airplane to stink!! Smell of bad, old gas!!! I can literally smell a mogas aircraft when brought into hangar for maintenance. Once on long cross country in Auto Fuel C172 years ago, called ahead trying to find FBO that sold Mogas.... Crusty oldtimer in high desert of California told me that if I wanted auto fuel, "Go land at a gas station"....

I wanted to make sure my plane had a STC available before I bought it so that when Avgas goes TU I'd be able to fly.

I think Mogas has some advantages over Avgas. No lead fouling and reduction in sticking valves come to mind. Cleaner combustion chambers and plugs and oil result.

I think much of the misery to the rubber and seals in the system comes from alcohol contamination, and not the Mogas itself.

I concur it does not have the stability of Avgas and degrades faster. Plus it does not smell as nice.

It's a tough call.

IF the STC was just a few decals I'd run it. But with the airframe there are several costly mods that have to be made. I did the math and the cost recovery for me would have been 7-10 years if I got the conversion, so I just continue to run Avgas.

I was unaware that mogas had ethanol or alcohol in it here in Alaska. That changes things. I thought that was just a lower 48 tree hugger thing! How can a guy tell what's in his fuel?

Inexpensive alcohol testers are available from the STC provider. I bet you can get one at the autoparts store as well.

There is a way to check dropping some in a test tube with water and measuring the change in meniscus but I don't remember the trick.

Got it. ethanol pulls water into the fuel. If you have more gas than you started with after adding water, you have ethanol present. Pretty sure I could perform this test with just a fuel drainer. I bet their just adding a surfactant like soap to help the water absorb into the alcohol. Wonder what the chemical is. I'll have to try this little experiment.

Has anyone around these parts tested our local fuels lately? If so what was the content and where did the fuel come from? I have some buddies that operate at Tesoro Refinery i'll ask around.

According to pure-gas.org Alaska is an Ethanol Free State. Where are we seeing ethanol or alcohol in our fuels in alaska?

http://pure-gas.org/

I thought that was just a lower 48 tree hugger thing!

Yeah, but a dumb ass tree hugger thing. The ETOH in our fuel has a lot more to do with the mid-West farm (read that Archer Daniel Midlands) lobby than clean air.

When all the environmental issues are taken into account (fertilizer, fuel to grow and harvest, etc. ) not to mention the increased food costs; ETOH in our fuel is not a great deal environmentally or financially, unless you are ADM or Cargille, etc..

Unfortunately the oil companies' alternate solution was an unmitigated disaster what with contaminating the drinking water.

As long as ADM and their cohorts control Congress, we are going to be stuck w/ Ethanol in our gas.

Stepping off soap box now.

TD

Once again the best government money can buy.