You could weld a full fuel tank without blowing your self to the moon by inserting a thick hose from the tail muffler pipe into the inlet of the tank giving enough time for all the vapor comes out then with the engine running you can start welding with out problem!!!
According to a linguist I know the barrier between middle English and modern English is Shakespeare.
So, late 1500s/early 1600s. I was close. 
You’re going to be valuable, but they’re going to wonder why your stuff don’t burn so good. It’s more like 1:3:16! 
I worked at Blockbuster from 2000 to 2013. They never seemed to have any significant updates to their computer system. So I could go back as far as 1985 and work for them.
Actually I wouldn’t mind that all that much. I loved working for Blockbuster.
Fun to know, but prior to the 19th century it would simply be assumed you were insane.
“You must be insane.” And anyway, the practicalities are a bit more complex than just jamming moldy bread into someone. Most bread m old is not penicillum.
“You must be insane.”
“You must be insane.”
Prior to Copernicus et al: “You must be insane.”
I’m not trying to be a jerk here, it’s just that knowing scientific tidbits doesn’t make you any money, doesn’t make you useful, and will not be accepted if it’s too far ahead of accepted science. Mountains being caused by continental drift is neat-o and all but was not accepted science until just forty or fifty years ago or so, and how it would be of use to anyone, really, I don’t understand.
One of my favourite history of science stories is the fact that for quite a long time science could not figure out how old the Earth was because they could not understand how the Sun kept on going. Long after the science of geography was coming up with mo9unds of evidence the Earth was billions of years old, the idea was considered kind of crazy for the simple reason that no one could come up with any plausible explanation as to how the Sun could be that old - because they thought the sun was a burning object, and there was no way you could finagle an explanation for the sun burning for billion of years. People were famously sensitive about talking about it around Lord Kelvin.
It was only when the science of nuclear fission and fusion was figured out that scientists could realize that the Sun was not burning at all, and suddenly the math worked. If you tried to explain this stuff to people in 1750 - uranium, hell, in 1750 they had not discovered frickin’ OXYGEN - they would think you were insane, and you don’t have the tools or knowledge to conduct the experiments to prove them wrong.
So could you identify sulfur and saltpeter to make it into gun powder? Could you make penicillin without modern lab equipment without killing anyone? Earth goes around the sun? Prove it. What use will the age of the earth or the minerals on top of Everest be? Where’d you get that prism? What year will the mongols invade? How do you stop the mongols?
I make stone tools as well as primitive bows, arrows, atlatls etc. My skills would be useful all the way back to the beginning.
Build a microscope. Observe animalcules. Assert animalcules are the cause of some diseases. Observe that heat, acids, alcohol, bleach, etc will kill animalcules.
People didn’t just dismiss theories with a “He’s INSANE!!!”. They just didn’t think about it. People get sick. Why? Beats me. God’s will?
There were all sorts of theories about diseases. Bad air, evil spirits, curses, witches, God’s wrath, moral decay. And one of those theories was dirt and filth cause illness. Which was correct, although they didn’t know the causal mechanism, which was the animalcules living in the filth. People didn’t understand how diseases spread from person to person, just that if you were near a sick person you might somehow get sick from them.
I don’t think there would be any such “Ah! Insane! He challenges our sacred traditions!” The problem would be convincing people to actually take action based on your recommendations. People can believe in germs, but still not actually do the things you need to do to prevent the transmission of germs. Or they might think you could be right, you could be wrong, but there’s no particular reason to believe you. Sometimes rocks fall out of the sky? Sure, maybe they do, but it doesn’t seem likely, and why should we believe this one guy who says one time he saw a rock fall out of the sky? It seems unbelievable, so there’s no reason to believe it, even if we can’t explain the origin of this particular odd iron-rich rock.
Or to put it another way, today we have no idea what “dark matter” is. Someone from 100 years in the future arrives, and says, “Oh yeah, dark matter is actually a flavor of neutrino with mass called the lemurino, and I forget much else about it, but that’s the answer.” Would we believe such a person? Maybe, if we had good reason to suspect that they really did have all kinds of esoteric but random knowledge.
I’m equally useless in the past and future as I am in the present.
Good points. Keep in mind that basic literacy (reading and writing simple sentences) wasn’t much of a given even one hundred years ago. A modern high school graduate’s level of reading, writing, and math could get you an office clerk or retail management job in the 1700’s. You’d need to be able to read labels, track inventory, and write letters to suppliers asking for more wheat or whatever. Most people in those days couldn’t do it. A basic clerk’s job certainly wouldn’t make you rich in those days, but it would keep you from starving and you could go almost anywhere and find jobs available.
If you are reasonably young (under 35-ish), male, and in halfway decent health, the Army would certainly take you as an infantryman. With basic literacy and math skills, you might have a decent chance of qualifying for officer training, especially in the USA where the slots weren’t already all earmarked for nobility.
On the other hand, it just occurred to me that I’m heavily reliant on several medications that didn’t exist back in 1985. So there’s that.
Welcome. I think I can safely say on behalf of most of the upstanding members of this community, “Dafuq?” 
Does anyone else see a connection to this topic?
Reporting as… something.
Maybe back in the beginning but what about since the iron age?
I suspect you’d have a hard time making a pencil let alone a microscope. Seriously, look up Milton Friedman talking about how to make a pencil.
It’s not my professional skills that would let me travel back far in time (programmer). Really, it’s my ability to adapt combined with my vast knowledge of seemingly useless trivia. I’d still rather take a book or two full of patents with me, but sparing that, I’d probably rise “out of the ashes” and into the riches pretty quick just based on random knowledge giving me an edge. From a moderately deep knowledge of history, and a well rounded education and hobby learning of math and science, I think I’d do pretty good. At least until I got speared for being “uppity.” (I know martial arts too, but I figure compared to their hands on skills and knowledge in that field, my 5 years of a rather unimpressive martial arts branch and minimal SCA involvement, would be more of a hinderance than a help)
How about going into the future? In a couple of hundred years or so I will be a font of information for historians of the future.
I am a lawyer in the common law tradition, so I think my relevant period of time would be lives in being plus 21 years.
As a strong chess player and coach, I should do well.
The current laws of chess were established around 1500, so that’s as far back as my knowledge would be useful.
I could:
- find a wealthy patron who would back me to become World Champion (e.g. I’d know the ideas of Philidor, Steinitz, Tarrasch etc. hundreds of years before anyone else)
- get a carpenter to make me a Chess Automaton
- write chess books (excuse me Mr. Gutenberg - I’m an author!)