Thanks pishta, and I've posted this before
COMPRESSION. I don't know what the minimum is, for a worn engine, I'd guess much less than 80 PSI, it hain't gonna run or not very well. Maybe we can start a contest, LOL, to see who's got the "worst" engine that still starts and runs........without pushing it at 40 mph
FUEL. Good clean fuel, not contaminated, and MUST actually be GASOLINE, IE not JP-4, kerosene, etc. Don't laugh.......it happens
SPARK. Good hot spark at the right TIME
"Back in the day," early '70's I used to have a Chubby friend, put a 396 into a 57 Chev. I had a part time job at the NAS Miramar hobby shop, and one Sat, he was trying to get it to fire. I'd helped him install the cam and do a prelim valve adjust, so I KNEW that was OK.
He bothered me several times during the morning, asking for advice, a spare coil, this and that. I was busy otherwise.
Finally he came in, "HELP" I canNOT get this to fire. So I go out there. Here's the "admiring crowd," none of them helpful, of course. Everybody was drinking sodas. He hands me a soda can. "We are priming it from this," he says, "it doesn't have fuel from the pump yet."
I smelled the can to make sure it wasn't SODA.
"Take this can and go get me some GAS I said."
I don't know where they got it, but they managed to get jet fuel in that soda can. NO!!! It would not FIRE!!! on JP-? LOL
An unrelated side note: This "friend" turned out to be a real traiter. One weekend I caught him with several of MY wrenches in HIS toolbox. That was the END of that friendship.