I thought you said the guy did a good job and you trusted his rebuild?
I'm not the all knowing on motors but from my understanding high rpms will spin bearings. But I'm sure you knew that allready? I sure hope you weren't beating on a motor with a fresh rebuild.
Ring-seating procedure calls for high cylinder pressure. Nissan motors call for runs up to 6500 RPM under load, then coasting back to 2500. Repeat for at least 5 runs. Once the rings seat and the smoke stops, don't run the motor hard again for at least 200 miles. If you do run the motor hard after that, it'll still work, it just won't have the same kind of longevity. If it was assembled properly, a bearing would not have spun.
That's advice given to me by a man who's been building Nissans since they carried Datsun badges. I trust him because I've seen his work firsthand. Man has 11 Datsun 510s, among a collection of 38 cars at the moment.
I trusted the PO's rebuild until it spun a bearing. Then I realized he cut corners and used procedures specific to Chevies when putting this DOHC Nissan motor back together.
My guess is that Texas Mexicans are probably poor, and therefore buy cars that already have problems, and dont have a lot of money to fix them when they break down further. Just a guess. Then again maybe you are right and your sweeping generalization about Mexican-ness equaling ****ty car maintenance is correct.
Texan Mexicans don't have pride in their work is the problem. The difference in cost between a bad fix and a good one isn't that much, but if you have any pride you'll do it well regardless. "Almost good enough" is a philosophy you see often around here.
For that matter, Mexicans aren't the only ones steeped in poverty, but not everyone that poor does as bad a fix to their car. Just comes down to pride in your work. Call it a cultural thing I guess.
Anyway, I'm not really concerned by the bad build. These motors are cheap, the head is remanufactured by Cylinder Head Exchange, and the clearance to get it in and out is plentiful. I'll just put the reman head on a slightly newer motor and drop it in. Plus I'm familiar with Nissans and I've pulled these motors from these cars. All in all if I end up with a different motor in there for $500, that puts me at $1700 for a stock 240SX which is still half the going rate these days.
Eat me and don't call it a Nissan thing. That's like saying snapped front axle shafts are a Jeep thing.