Aviation gas in Model A

[Ca. Kid]

Yesterday when I was at the county airport a club member called me and said he was out of gas in his Model A near the airport. I explained to him we didn't have auto gas, only avgas 100LL, which is 100 octane with no alcohol and a small percentage of lead. I have burned 100LL in everything from an antique Curtis 0X-5 to chainsaws with no problem. He agreed that it should be ok as he only had 5 miles to get home. We put in 2 gallons and off he went.
Later that evening he called and told me what happened. After about 3 miles the engine stared heating up and missing, by the time he got home it was running on 2 cylinders with a blown head gasket. He was pulling the head last night so I hope that was the only damage.
My question is do any of you petro chemical engineers have any ideas as to why 100LL would cause this or was it just a coincidence?

[Jason in TX]

Well, with that high of octane, he should be able to run extreme advance. As far as the heat, he may have been running the engine too retarded.

Also, the lead can foul the plugs. He may just want to pull the plugs and see if they are really dirty.

I would think you could run a model A on moonshine though without harming it.

[CarlG]

Model As ran on leaded gas for years before the advent of "unleaded"

When I worked for an aricraft repair facility, we used avgas (100LL) in all our off road equipment -- forklifts, tugs, weed eaters, lawnmowers, etc. This was usually gas we had drained out of aircraft tanks and could no longer be used. It was easier to use it that way than find a way to dispose of it.

[Purdy Swoft]

I ran 100 octane leaded gas as long as I could get it in all of my cars, lawn mower and chain saw with no problems. I wish I still had a soarce. Leaded fuel will cause carbon deposits but thatr was never really a problem for me. I would MUCH!!! MUCH!!! rather have 100 octane leaded gas than unleaded ethanol adultrated gas any day. If something isn't done about the ethanol adultrated fuel,It will be the death of the old car hobby.

[Pete]

I would say your friend's problem was not related to the av gas.

[real550A]

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Purdy, I agree....years ago, we had "Clark Super 100" stations all over Minnesota. All they sold was 100 octane leaded gasoline. I could tell the difference right away when I put it in a Cushman Eagle, or mini-bike. It also made the old 4 cyl. Porsche bathtubs go fast! Looking forward to the end of the ethanol nonsense.

[Purdy Swoft]

I wish I had kept the Cushman eagle . I agree, The leaded 100 octane gas made a huge difference in power and reduction of timing knock.

[H. L. Chauvin]

If one visits coastal areas, one finds complaints that ethanol gas dissolves marine rubber gas lines & certain synthetic marine gas tanks -- many 4 cycle engine boat owners have already switched to aviation gas with absolutely no problems.

[Louis]

Back in the late 70's when we defuel'd acft. for maint. a lot of the purple 115/145 ended in the gas tank of my old chevy. along with some of the other maint. guys vech. no one had any problems from using it, I coulden't tell any real diff. in it except for the price of course .
I don't think high oct. has to do with power as much it does with anti. knock in hi comp. eng's run at hi power, The 4360's of the day would pull 62.5 in of manifold press at max power. I never ran my old chevy. that hard to really tell the diff. in power then the reg. auto. gas.
I doubt if the avgas had anything to do with "A" model eng's problem's.
Sounds like an operator problem to me .....JMHO.

[John Butts in CT]

At the risk of igniting a firestorm of criticism, here goes:

Leaded gas was NOT universally available '28-'31.

STOCK "A's" didn't need it then, nor do they need it now.

With that off my chest, here's my personal fuel formula from a very old post (and you can now add another year to the dates in the post, and all's still well with E-10.... still good.)... (as for octane.... mix and match until your car's happy... c'mon guys/gals... it's only a few cents difference per tank):

Here's a repeat of a post of mine from an old "Do A's tolerate Ethanol..." thread. I still swear by it. MMO and Star Tron are two of my six steps to coping with ethanol:

"In prior threads here and on the old Barn I shared my experiences with creeping neoprene goo after E-5 appeared in New England. I'm not going to cover old ground; we've all heard about how the fuel separates, evaporates, turns to corn syrup, dissolves neoprene, etc., etc.

Cutting to the chase, the following formula has given me four (SIX as of 2011!)consecutive years of driving without a single fuel-related problem... E-5, E-10, 87, 89, 91 Octane, whatever:

1) HARD Neoprene gauge float, NOT CORK.
2) CORK gauge gaskets, NOT NEOPRENE.
3) MMO added to gas, per manufacturer's instructions.
4) Star Brite "Star Tron" (the blue stuff) added to gas, also per
manufacturer's instructions.
5) Run carb dry at the end of each day.
6) The on-board computer (driver) needs to adjust the spark and
GAV "to taste." (The car's taste, that is.)

There, I said it; take it or leave it, it works for me.

Whether it's a day, a week, or a month between starts, the "A" starts first time, every time. (As do my lawn mowers and snow blower, on the same fuel diet, no matter how long the fuel sits.)"

[MrTube]

I find it interesting so many complain about modern day gasoline. I don't know about when the "A" came out, but the mid 1920s WhirlWind airplane engine I mentioned in another thread called for 50 octane fuel. I'm willing to bet the same was available in the model A years.

Yea, we have crap fuel these days, whatever you say.

[700rpm]

"3) MMO added to gas, per manufacturer's instructions.
4) Star Brite "Star Tron" (the blue stuff) added to gas, also per
manufacturer's instructions."

Do you find these better, worse, or no different from adding Sta-bil to the tank when putting the car away for a few months?

[John Butts in CT]

Originally Posted by 700rpm

"3) MMO added to gas, per manufacturer's instructions.
4) Star Brite "Star Tron" (the blue stuff) added to gas, also per
manufacturer's instructions."

Do you find these better, worse, or no different from adding Sta-bil to the tank when putting the car away for a few months?

Hey, Ray:

Call me "old fashioned," but I add them BOTH.

No worries.

JWB

[John Butts in CT]

IMHO, custom-mixed fuel for a Model "A" is like home cooking... better than the "fast food" stuff.

My formula may not be the BEST for everyone, but it works for me. Give it a try.

All the best.

JWB

[Patrick L.]

The only gasoline available at airports in this area is 100LL [ well, a few carry mo-gas]..It hasn't hurt any of the airport equipment we've been running it in over the years.. I use it in a lot of my stuff that sits around a lot as it doesn't break down and varnish..
I believe it should not hurt a Model A at all..
Back in the day when Continentals called for 80 octane no lead and it became unavailable the only thing left was 100 octane low lead.. All the local 'experts' said it would ruin the Continentals and cause guide problems,, I didn't by it.. Now, 15 years later, I can't think of a single problem it caused..

[Bruce Adams]

Originally Posted by 700rpm

"3) MMO added to gas, per manufacturer's instructions.
4) Star Brite "Star Tron" (the blue stuff) added to gas, also per
manufacturer's instructions."

Do you find these better, worse, or no different from adding Sta-bil to the tank when putting the car away for a few months?

Sta Bil now makes a "Marine Formula" for the E-10 which is equivalant to Star Brite's "Star-Tron" which came out a couple of years before Sta-Bil's product.

MMO is totally different and is an upper cylinder lube. I use MMO faithfully in the Model A, and my seasonal engines get either the Star Brite of Sta Bil product in ADDITION to running them dry at end of season. This has helped in all cases save for deteriorated vinyl fuel connections.

[V4F]

without reading all the replies , back when i was racing dirt cars we tried it . the problem we found was 1) to much lead 2) altitude additives & so on . turned out not to be our answer ...............

[MALAK]

Originally Posted by Ca. Kid

Yesterday when I was at the county airport a club member called me and said he was out of gas in his Model A near the airport. I explained to him we didn't have auto gas, only avgas 100LL, which is 100 octane with no alcohol and a small percentage of lead. I have burned 100LL in everything from an antique Curtis 0X-5 to chainsaws with no problem. He agreed that it should be ok as he only had 5 miles to get home. We put in 2 gallons and off he went.
Later that evening he called and told me what happened. After about 3 miles the engine stared heating up and missing, by the time he got home it was running on 2 cylinders with a blown head gasket. He was pulling the head last night so I hope that was the only damage.
My question is do any of you petro chemical engineers have any ideas as to why 100LL would cause this or was it just a coincidence?

It is a common misconception that high octane gasoline burns hotter and will provide a performance increase over lower octane fuels. This is bunk. Sure if any given engine is running too low an octane and as a result has preignition/detonation then running a higher octane will provide a performance increase by minimizing/eliminating those conditions. However the additives required to raise the octane rating also lower the BTU/unit. http://www.appropedia.org/Energy_content_of_fuels
The BTU difference between Avgas and 87 Octane is only 3.8%.

Jason in TX Re: Aviation gas in Model A
Well, with that high of octane, he should be able to run extreme advance. As far as the heat, he may have been running the engine to retarded.

Also, the lead can foul the plugs. He may just want to pull the plugs and see if they are really dirty.

I would think you could run a model A on moonshine though without harming it.

So I'm with Jason on this one. He may have been running it a little on the retarded side but unless he drove it up a 10% grade for 20 miles I doubt it made any significant difference. Sounds more coincidental to me.

[Aerocraft]

I would agree with those that believe the problem is not related to av-gas. I burn 100LL in the Model A engines in our Pietenpol Aircamper. Years ago, I used 80 octane av-gas until it was no longer available and then switched to 100LL for our first Pietenpol. I would much rather use av-gas than ethanol laced auto gas. Gar Williams

[Paul from Maine]

About 20 years ago, I drained about ten or fifteen gallons of 100LL out of a Cessna 182 straight into the '73 Galaxie I was driving at the time. No performance difference. Been runnin' 100LL in my low compression O-200 Continental for over twenty years. Besides fouling the plugs once in a while, no performance difference from the old 80 octane or car gas we used to use (had an STC for AutoGas). Can't believe that 100LL ruined an A engine. The O-360 in the Cherokee loves 100LL. Hasn't blown that up yet, either!