Timing chain pondering
 

Hi guys, I am in the middle of replacing my head gaskets on my disco (it's at 170K, it was bound to happen), and The engine is currently down to short block assembly. I was wondering while I have it this far apart, should I go ahead and replace the timing chain (or is it a belt? I know so little about thes Buick engines rover uses)? The carfax show it has never been replaced, and the disco has 172k on it. What is the lifespan of a timing chain/belt on this?

I think the lifespan of the timing chain is 200k.

If it had a timing belt it would nedd to be replaced every 60,000 miles, but it does not have a timing belt, it has a timing chain.
The timing chain should last the life of the engine.
There is alot more work in replacing the timing chain that you think.
I would leave it alone if it were me.

My old work van (a E-250) still has its original timing chain and it has almost 270k on it and its still going strong.
A friend of mine at work him van has almost 350k with the original chain.
So my point is, save your money.

Alrighty, I'll leave mine alone then, it felt like there was some slack between the crank and the cam when I turned the crank by hand. I have to replace the timing chain on my 1977 dodge pickup at 155k so that it wouldn't snap ( my father had one snap it it ruined the engine). But if it is meant to last the life of these engines, then I'll leave it alone.

Timing chains are always meant to last the life of the engine, if Dodge only wants their engines to last 150k thats their problem.
The timing set is cheap so if it makes you feel better it wont hurt.
If you already have the front cover off (I dont know why if all you are doing is head gaskets) then go for it.
Each to their own, if you want to set your truck on fire and roll it down a hill go for it man.
My engine is all original and I ain't touching anything if it ain't broke.

And the life of the engine is dependant on the timing chain not failing, so yes, replace it and consider pulling the oil pump and replacing it also, they wear and more so, they tend to break the outer ring.

Thanks again guys, I will change it given the information provided and just for peace of mind :). I hope my engine will last me while after this so I don't have to drop an old porshe 944 engine sitting around in it

At your mileage, you might also want to consider checking/replacing the oil pump gears, that do wear out and or break.