1931 Fuel octane levels

[mistyreiny1]

I have a 1931 ford model aa but i no idea what octane the gas should be and i cant find what level the model t is supposed to be. if i knew what the model t was i could guess. And i know about the lead substitute in it.

[bart78]

I thought they had unleaded gas then. I did not think it was till the mid thirties they came out with leaded gas.

[jrapose]

Good question, my car likes the lowest garbage I can find .....never premimum...
I once tried keroscene and it would run on it...would not start using it but once is was running and warmed up it ran, but smoked .... I wanted to de-carbon it and kerosene sure did it...

I have several roadsters....one with a C motor (yes I know they never built a C" and one that is diesel powered.

Joel

[jrapose]

The black car in the picture actually is diesel powered.. (Opel diesel) 65hp and sounds almost stock....lots of fun when you are in the gas station and someone runs over to tell you that you will ruin your engine using diesel.....
I always say "Model A's will run on anything" never admit that it is a diesel.
I get over 40mpg and the power curve is close enough to the Model A stock motor that it performs well..

It also has front disk brakes I made...
This is my "driver" that I use almost every day.

Joel

[28ACoupe]

If you run kerosene in these cars, does it produce Prius repellant?

[Skrain]

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I'd actually be more concerned about finding a source of Non-Ethanol Gas if you can.
There are several websites with lists of stations nationwide that sell real gas, no corn...

[Skrain]

Originally Posted by jrapose

The black car in the picture actually is diesel powered.. (Opel diesel) 65hp and sounds almost stock....lots of fun when you are in the gas station and someone runs over to tell you that you will ruin your engine using diesel.....
I always say "Model A's will run on anything" never admit that it is a diesel.
I get over 40mpg and the power curve is close enough to the Model A stock motor that it performs well..

It also has front disk brakes I made...
This is my "driver" that I use almost every day.

Joel

I'd LOVE to see some pictures of the conversion!

[Sparky]

The lowest octane gas available today is much higher than what was available back in 1930. As was noted above, lead additive wasn't used then either so unleaded gas is fine.

[MikeK]

Average octane in 1930 was 60 RON. Tetra-ethyl lead, developed in the early 20's by Dupont and controlled by GM wasn't popular or readily available nationwide for another 10 years. 'Ole Henry never made any engines that needed a fuel additive made and promoted by rivals.

[mistyreiny1]

Bart78, lead was introduced in the 30's then removed not because it was toxic, but damaging to all parts

[bart78]

I think it was 1936 that lead was being used in most gas.

[TerryH]

There are many states that only allow ethanol gas to be sold for general use, California being one of them. I have been using it for at least 6 years, and although I am not a big fan of it, I have had absolutely no issues with it as far as my Model A is concerned....my car runs just fine, but probably does not get as good as gas mileage as with non-ethanol gas.

[Patrick L.]

During the T and A years the octane rating was about 40 for cars/equipment and 75 for aviation. Thru the 30s it kept creeping higher with addition of lead and better refining.

[Skrain]

The biggest problems with corn gas is the fact that it will break down the cork float on the fuel gauge over time, and slowly dissolve, or at least soften some of the seals on the gauge as well, causing some leakage.
Also, it seems to be a bit more susceptible to vapor lock, since the ethanol lowers the flash point of the fuel.

[Bob from Northport]

On Dec. 9, 1921 a chemist named Charles Kettering and a group of men discovered that adding lead to fuel stopped the engine knocks that were causing lots of problems in engines. In 1922, oil companies started adding lead for engine knocking and octane levels. By 1925 a number of oil company employees had died from lead poising. It was a serious problem till 1974, when the EPA mandated the removal of lead.
I'm not sure about Octane level rating then. Regular has been 87 for years. Our Model A's seem to run best on 89. No premium.

Bob

[KGBnut]

Just remember, higher octane is needed to avoid pre-ignition in high-compression engines. Octane is essentially a measure of difficulty to ignite...the higher the octane rating the harder it is to make it go bang.

Model As (and by their nature nearly all flatheads) have low compression ratios.

In fact, one of the biggest reasons for the switch to overhead valves was the ability to get higher compression ratios, but this necessitated the higher octane fuels.

[Aerocraft]

In the late fifties, when my Coupe and I were stationed at Otis AFB, I would occasionally add a bucket of JP-4 (jet fuel) to the gas tank rather than dumping the fuel after cleaning the belly on my F-101. It started hard when cold, smelled funny, but ran OK.

Gar Williams

[KGBnut]

Hey, I was stationed at Otis...but more recently. I was there 1988-1992...long before I got my Model A.

[BlueSunoco]

I have a gasoline globe around somewhere that had a rating of '68' Octane if I recall. Globe was from about 1934.

That was hot stuff in it's day. So 87 Octane today would be more than enough for a Model A Ford.

[Skrain]

Here you go, guys. I know it's a long article, but it will explain a lot of things.

Spark ignition engines are designed to burn gasoline in a controlled process called deflagration. In some cases, however, the unburned mixture can autoignite (detonate from pressure and heat alone, rather than ignite from the spark plug at exactly the right time), which causes rapid pressure rise which can damage the engine. This phenomenon is often referred to as engine knocking or end-gas knock. One way to reduce knock in spark ignition engines is to increase the gasoline's resistance to autoignition, which is expressed by its octane rating.
Octane rating is measured relative to a mixture of 2,2,4-trimethylpentane (an isomer of octane) and n-heptane. There are different conventions for expressing octane ratings, so a fuel may have several different octane ratings based on the measure used. Research octane number (RON) for commercially-available gasoline varies by country. In Finland, Sweden, and Norway, 95 RON is the standard for regular unleaded gasoline and 98 RON is also available as a more expensive option. In the UK, ordinary regular unleaded gasoline is 91 RON (not commonly available), premium unleaded gasoline is always 95 RON, and super unleaded is usually 97-98 RON. However, both Shell and BP produce fuel at 102 RON for cars with high-performance engines, and the supermarket chain Tesco began in 2006 to sell super unleaded gasoline rated at 99 RON. In the US, octane ratings in unleaded fuels can vary between 86 and 87 AKI (91-92 RON) for regular, through 89-90 AKI (94-95 RON) for mid-grade (European premium), up to 90-94 AKI (95-99 RON) for premium (European super).
The octane rating became important as the military sought higher output for aircraft engines in the late 1930s and the 1940s. A higher octane rating allows a higher compression ratio or supercharger boost, and thus higher temperatures and pressures, which translate to higher power output. Some scientists even predicted that a nation with a good supply of high octane gasoline would have the advantage in air power. In 1943, the Rolls Royce Merlin aero engine produced 1,320 horsepower (984 kW) using 100 RON fuel from a modest 27 liter displacement. Towards the end of the second world war, experiments were conducted using 150 RON fuel (100/150 avgas), obtained by adding 2,5% aniline to 100 octane avgas.[3]

[mistyreiny1]

I don't think my engine is supposed to have lead in the gas, it's a 1931, I know lead was introduced in the 1930s but I don't have a specific year. I figure adding lead to the gas won't matter, there's no catalytic converter to damage, but I wanted to ask for other opinions before I test it.

[Brother Hesekiel]

A Ford Model A engine does not need any lead in the fuel, neither does it need anything else than the cheapest gas available and the cheapest motor oil available, all of which still would be light years ahead of the highest quality gasoline and motor oil available 82 years ago.

Nothing can be gained by adding fuel substitutes, fueling with rocket fuel, or operating the engine on Ferrari Formula 1 motor oil.

[just plain bill]

I was in the service in 1955 and 1956 and was what was called a "wheeled vehicle mechanic" and at that time the US gov purchased 72 octane gasoline. I believe most regular gas was around 72 octane, I know the stuff they put in our 500 gallon farm pump was.

[Growley bear]

Dec 9, 1921:
GM engineers discover that leaded gas reduces "knock" in auto engines

Previous Day December 9 Calendar Next Day

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On this day, a young engineer at General Motors named Thomas Midgeley Jr. discovers that when he adds a compound called tetraethyl lead (TEL) to gasoline, he eliminates the unpleasant noises (known as "knock" or "pinging") that internal-combustion engines make when they run. Midgeley could scarcely have imagined the consequences of his discovery: For more than five decades, oil companies would saturate the gasoline they sold with lead--a deadly poison.
In 1911, a scientist named Charles Kettering, Midgeley's boss at GM, invented an electric ignition system for internal-combustion cars that made their old-fashioned hand-cranked starters obsolete. Now, driving a gas-fueled auto was no trouble at all. Unfortunately, as more and more people bought GM cars, more and more people noticed a problem: When they heated up, their engines made an alarming racket, banging and clattering as though their metal parts were loose under the hood.
The problem, Kettering and Midgeley eventually figured out, was that ordinary gasoline was much too explosive for spark-ignited car engines: that is, what we now call its octane (a measure of its resistance to detonation) was too low. To raise the fuel's octane level and make it less prone to detonation and knocking, Midgeley wrote later, he mixed it with almost anything he could think of, from "melted butter and camphor to ethyl acetate and aluminum chloride...[but] most of these had no more effect than spitting in the Great Lakes."
He found a couple of additives that did work, however, and lead was just one of them. Iodine worked, but producing it was much too complicated. Ethyl alcohol also worked, and it was cheap--however, anyone with an ordinary still could make it, which meant that GM could not patent it or profit from it. Thus, from a corporate point of view, lead was the best anti-knock additive there was.
In February 1923, a Dayton filling station sold the first tankful of leaded gasoline. A few GM engineers witnessed this big moment, but Midgeley did not, because he was in bed with severe lead poisoning. He recovered; however, in April 1924, lead poisoning killed two of his unluckier colleagues, and in October, five workers at a Standard Oil lead plant died too, after what one reporter called "wrenching fits of violent insanity." (Almost 40 of the plant's workers suffered severe neurological symptoms like hallucinations and seizures.)
Still, for decades auto and oil companies denied that lead posed any health risks. Finally, in the 1970s, the Environmental Protection Agency required that carmakers phase out lead-compatible engines in the cars they sold in the United States. Today, leaded gasoline is still in use in some parts of Eastern Europe, South America and the Middle East.

[modelAtony]

Originally Posted by mistyreiny1

I have a 1931 ford model aa but i no idea what octane the gas should be and i cant find what level the model t is supposed to be. if i knew what the model t was i could guess. And i know about the lead substitute in it.

Model a era pictures of gas station will sometimes show octane sign at 68.

[ped58]

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Does anyone remember Speedway 79 gas station's....guess what the octane was.