92 series Detroit Diesels

If it puts out a bit of black smoke on acceleration and runs out clean, it may just be the throttle delay.
A crude device that some times works . Or just ease up the pins slowly.

If you have black smoke while running, I would recommend old DDC tech to get involved .

I removed them from my 12V71TIs. When cold, the throttle delay kept the racks stiff and the engine would hunt for idle.
I have the newer control tubes also, with springs keeping a locked-up injector from binding the rod.
The throttle delay on the 71s is still the original design. There is no safety springs on the rod arm.

I can punch my 71 and make black smoke, but normal operation, I slowly advance the throttles and no problems. This is the only reason for them; reduce acceleration smoke.

I have never heard of one locking up the control rod but it is easily possible when you look at it..
It's something else to fail and disable your engine.

The throttle delay will not have any smoking effect on a good running engine. When climbing swells I have no smoke. Others trash their transom and blame the throttle delay in-correctly. Their just not running rite.

I have never witnessed a failure.
I heard of one. That may have been an installation issue.

I would not go after them just to do so, but the next time the covers are off you may consider it then.
Scribe the angle position and take some pictures, if you want to put them back on later.
Un-fasten the arm from the control rod and pull the piston from the cup. Don't drop the U bolt nuts into the head. That's it.
There is a tiny square head screw next to the cup that you are leaving on the head (valve cover bolt screws into the assembly). This is the factory set oil flow adjustment to the cup. Your not going to loos any oil pressure, I don't remember any spec or adjustment also. I left mine alone since so little oil flows into the cup.

It's not a big woo and if your running good,, remember one thing,, never kick a sleeping dawg.

71's rule.

Lots of 92's out there (although not nearly as many as the 71's given length of time they were produced). I got nearly 4,000 hours and over 20 years out of my 92's before they needed MOH. I think the 92's are like anything else, it depends on how you treat them and maintain them. Also really depends on what your priorities are. I'm guessing the hulls with 71's are older vs. the one's with 92's. Is speed a factor for you? What are the different fuel burn rates vs. speed? Have either of the boats you are looking at had MOH's?

In all of my experience, I've found that once the 92's got a few hundred hours on them, they'd lose 10-20% of their HP somewhere (not make top rpm was a common problem with them.) After that, they seemed to be hardly any faster than the 71's in the same boat. I mean like 1 knot faster, maybe 2 knots...... but nothing worth the fuel burn and hassles and much shorter lifespan. That being said, when buying a used boat, they have what they have.

I can only speak to the experience with the 92's in my boat. I've never had a problem reaching 2,350 RPM. Even right before time to MOH I would still get to full rpm if desired or needed and that was with nearly 4k hours on it. Perhaps folks are propping to close to max when boats are new to squeeze every knot out of them and as they grow weight, bottom fouls, etc RPM's are lost??

Definately. Most builders do that. But also most owners add thousands of pounds of crap to the boat, the bottom gets heavier with 20 coats of bottom paint over the years, and on and on.