I watched a couple of "kids" try to change a flat tire on a international pick up they had bought at a auction. After seeing them snap off 2 lug nuts by jumping on the four bar they were using I asked. "You do know that those are left hand threads?" Always take a second to look at something closely before you try to he-man your way through a project.
Stop welding and grinding in the shop at least a half hour before you decide to call it a day, or leave for a bite.
I agree with the post on double checking your fluids on a fresh motor. One of the first motors I ever built was a aluminum headed 4 cylinder race motor. I was excited to get it fired and started it with no water in it. Result - warped head and started scuffing the cylinders. Also, make sure your oil plug is in and tight after an oil change, happend twice to my friends race car. That's what happens when several people work on a car.
Thats a big one, especailly when you have a shop it's easy to forget the fluids. I keep dipsticks either in the cab or on the wall of any car that does not have fluid in it, then I tape over the dipstick holes. This gives me a double reminder that there are no fluids.
Be wary of advice from a doctor...remember, they get to bury their mistakes, while yours live on and can kill you!
Instead of wasting time cleaning plugs, checking timing, electrical trying to get the thing started make sure that the plugs are actually tightened.
I cooked the cam bearing (which was basically the head casting "plain" bearing) on an old motorcycle because I forgot to check the crankcase for oil before taking it for a test ride. It was a garage-sale find with an ignition problem. I changed the points, cleaned the carbs and it fired right up. Never even thought about the oil. Now I know why aircraft mechanics operate "by the book" every time. We may think it's anal, but it serves a purpose.
Ha!.... one of my dumbass A&P instructors when I was in school admitted that he dumped 5 quarts of oil in a continental recip before he noticed the puddle on the ground.
Anytime running the thing would be destructive...remove the keys from your pocket or the switch and put them in the engine compartment so you cannot just start the thing without thinking about it.
I got ambitious last spring when it got warm and decided to fire up the race engine and put a little heat in it. I ran around and connected the oil pump primer, added the oil to the oil tank and built pressure. had some C16 set away and filled the cell and a carb, put a fesh battery in it, turned the air on for the ignition (timing is air controlled). Then i stopped, i went thru the checklist...did i forget anything? nope, all bases covered. I hit the remote start and the engine lit right off but sounded a little flat. The other carb filled and now all the idle ckts were working but it still didn't sound right. I shut it off and heard some valve noise, i pulled a rocker box and i had forgot that i had backed the valves off for the winter! The pushrods had gone up against the rockers and just beat themselves to death, i had to replace all 16 jesel adjusters at $20each and a set of chromemoly pushrods for another $100 - $350 all told. Just because i didn't write a note to myself - 'no oil'! or 'adjust rockers' or something like that, just a note on the steering wheel to remind yourself. When we were serious racing and changed the nitrous tuneup John and i would check each others' pills and confirm before they went in. There is just no excuse some times, just no room for the dumb mistake.
Attention to detail! If you don't fully understand something, figure it out before you proceed. First week on the job at a Volvo dealer and was told to put a new ignition switch in a car. When I pulled the old one out, the connector came apart. I thought to myself luckily the wires had a little memory worn into them, so I put it back where it looked like it went. Wrapped it all up and put the key in ignition. Car starts and drags me between the lift and car all the while pushing my toolbox through the wall into the service lane. Luckily no one was hurt. Coulda been real ugly.
That is a good rule. To keep from forgetting lug nuts and oil and loose bolts and stuff, I put up a dry erase board in the garage. I make sure it's clean when I start, and I write down the things I need to double check at the end of the project. If something weird comes up that isn't in the original plan, I write it on the board. When I am finishing up, I erase the items on the board as I check them. When the board is clean, I am ready to fire it up.
We had a shop kid that did some odd jobs for us & was wanting to learn the trade. He worked with me doing a complete brake job on a daily driver,disc/drum deal,,stocker. Machined drums & rotors,cleaned up all hardware etc. I had him put the wheels back on & showed him impact gun basics,not to overtighten,cross tightening etc. I just happend to look over when he was putting the hub caps on & noticed the stock tapered lugnuts were on backwards. I explained *that* to him & his comment was,,"I just thought they looked better with the pointy side facing out"....
after a year of haggling with the wife and finally getting the approval (don't act like I didn't need it either, you all know where i'm coming from)...and then the doctor my wife works for giving me a 1951 dodge d100, I was well on my way. Got it home and full of pee and pepper, I decided to try and start it up. Poured gas down the carb, put a jumper on it and voom...there she goes, running like a charm. THEN....BANG BOOM GRIND....the motor locked up quicker then my daddy when I asked for money as a kid. Didn't check the water or the oil. #2.....same truck, pulled into barn to start working on and decided that i would work on something I knew how to work on. So, I thought. I needed to work on the brakes and change the wheels. Welp...after many hours of trying to get the lug nuts off and breaking 3 studs...I got out the grinder and cut them off. Only to later be told, "you do know those are reveresed threads don't you (by my daddy of course)? Nope, sure didn't. So, now that i'm over the "who the heck are your to tell me stage"...things run much much better. Now, I've just got to get something back here to work on. Life throws curves at you, but God gives you batting instructions.
Don't pick up something you just welded with your bare hands to look at how pretty your bead is. Wish I'd learn from my own mistake, because I've done it more than once, twice, even three times. One of these days, I'm going to learn that fire can make metal really f***ing hot, and that I shouldn't touch it immediately afterwards.
If you have an engine on an engine stand, make sure it's the kind of stand that is stable enough before you try to spin the engine to get a better angle to work on it. Gravity is a bitch!