Been three days since the original post. He must not have liked the answers provided.
As our old friend, OK4450 used to say, “You won’t notice anything unusual until a millisecond AFTER the belt snaps, with no warning whatsoever”.
Yup, I noticed no difference until I pulled out of my driveway then engine just quit. Non-interference so no drama. Early
Pinto, replacement took about 20 minutes. But I learned from that, any car I had with a timing belt got belt replaced earlier than recommended interval.
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Just to be fair, there are technical advantages for why the manufacturer’s switched from chains to timing belts. First, a belt has much less mass than a chain, and less mass makes the car lighter, and less rotational inertia makes the engine more responsive. Also there’s no need to lube a belt, which significantly simplifies the engine design, in addition to eliminating important oil-leak sources. The downside is the belt has to be replaced once in a while. Were I to lodge a complaint about timing belts, it would focus on the time it takes mechanics to do this job, not that it had to be done. A manufacturer’s modification to the engine and engine compartment design is how to solve the timing belt problem imho.
Seems unlikely the chains stretch in the sense that the metal components stretch. It’s probably like bicycle chain-stretch, the holes in the chain’s side-plate/rivet interface wears, grit caused metal erosion results in an elongated hole. The larger the hole in each link, the longer the chain. This is one reason why oil and filter changes should never be deferred. If only for the timing chain, common sense says to error on the side of freshening the oil and filter too frequently than too infrequently.
Whatever wears - you probably are correct, and it’s the pin holes that wear - but those mid-cam detroit engines’ chains wore out faster than rubber timing belts. I’ve seen them wearing through the timing cover. One of the reason - other than crappy quality - was tendency to accumulate carbon behind the timing cover even with regular maintenance. And carbon, as you know, is ultimately a [cheap] diamond thus very hard and abrasive.
I have never seen a worn Toyota chain. At one point, their 22R/22RE had double chains but Toyota decided it was an overkill and switched to single row. The only thing that eventually required replacement on those engines was tensioner. If I was on the market for a used truck, I would go with Toyota with 22RE 2.7 reincarnation. Have to admit that 3.0V6 was garbage. By Toyota’s standards, not ford’s. It - just like the next [MUCH better] generation 3.4 had belt. Starting in 2004, I think all but 4.7 Toyota engines had chains, and my 2004 4Runner with 280,000+ miles is as quiet as the day I drove it from the showroom.