Here are pros and cons about belts and chains, as I posted about a year ago when I changed my belt:
Belt
Pro
It is inexpensive.
It is outside the engine, such that the debris caused by wear is not deposited in the engine oil, where it can cause further wear.
It is outside the engine and is light weight, such that the damage it may cause during failure (in a non-interference engine) is minimized, and often is zero. Been there, seen that, in a friend's 1986 Camry 4-cylinder.
It is light weight, such that the engine is more efficient, in that accelerating to a higher RPM requires investing less kinetic energy in the belt than it would in a chain. This helps fuel economy, making it less difficult, other things being equal, to satisfy CAFE standards.
It is quiet and, assuming it doesn't fail, reliable.
It typically doesn't stretch noticeably over its useful life.
Its replacement part cost is low, much lower than a chain.
Its replacement labor cost, due to the time required, can be low, depending on the engine design, for example the 4 cylinder Camry or the 4 cylinder Volvo, both of the 1980's.
Con
It requires periodic replacement, and the replacement period is relatively short, typically 40K to 90K miles.
Its replacement labor cost, due to the time required, can be high, depending on the engine design, for example the 4.7L I-Force V8.
Chain
Pro
It is long-lived.
It is usually quiet and, assuming it doesn't fail, reliable.
Con
It is expensive, at least more expensive than a belt.
It is inside the engine, such that the debris caused by wear is deposited in the engine oil, where it can cause further wear. Considering that it is composed of hundreds of tiny pieces which move against each other with every crankshaft revolution, the potential for shedding wear particles, especially during a break-in period, is relatively high.
It is inside the engine and is heavy weight, such that the damage it may cause during failure (even in a non-interference engine) is maximized, and often is catastrophic. The kinetic energy of the moving chain is high, as is its mass, and so stopping the moving chain when it fails can actually break the engine block. Been there, seen that.
It is heavy weight, such that the engine is less efficient, in that accelerating to a higher RPM requires investing more kinetic energy in the chain than it would in a belt. This hurts fuel economy, making it more difficult, other things being equal, to satisfy CAFE standards.
It requires periodic replacement, even though the replacement period is relatively long, often 200K miles or more. Chains wear and don't last forever.
It typically stretches noticeably over its useful life, thereby affecting valve timing toward the end of its life.
Its replacement part cost is high, much higher than a belt.
Its replacement labor cost, due to the time required, can be high, depending on the engine design, for example the 5.7L I-Force V8.
So:
Pick one.
I prefer a belt.
I have changed belts in both my Tundra (once) and my wife's previous car (twice), a 1986 Camry. The Tundra took me 10 hours, and the Camry took about 1 1/2 hours the first time, about one hour the second.
What I prefer about it is two things: 1) I very much like the fact that it is not an internal engine part, meaning nothing it does can put contaminants into the oil. A chain, with its hundreds of moving parts in rubbing contact with each other, is just the opposite; and, 2) I very much like that it makes the engine more efficient, as there is simply less mass for the engine to speed up and slow down as it runs.
My bottom line is, it works well, it has advantages, and I accept the maintenance penalty involved.
Your mileage my vary.
Addendum added today:
Don't discount the fact that the belt is external to the engine block, so it doesn't deposit wear particles in the engine oil, as chains do. The 4.7L V8 apparently is a very long-lived engine, and likely this is a big reason why. The most important item in a recipe for long-lived engines is keep the oil clean, and not putting crud in the oil is a big help.
I stated above that it took me 10 hours to change the belt in my Tundra. Kindly don't jump to the conclusion that it is a horrible, time-consuming job. It isn't.
My brother's employer owns and runs a magnificent auto service shop. He changed the belt in his Tundra (borrowing my crankshaft pulley SST to do so) and it took him only four hours. The differences are: 1) he makes a living at such things, so for him, time is money; 2) I am retired, so I take frequent naps and such, as how long it takes isn't important; and, 3) I typically do slow, meticulous work, so it often takes me a long time.
Seriously, this is an easy job. Just like eating an elephant, do it one easy bite at a time.
