HT4100 Timing Chain Replacement

Hi, how often do i need to change /replace the  timing chain on my 4.1 deville?
I have 175000 miles on it. Do i need to worry about it?
How do i find out if i need to replace the timing chain?

Thanks

An GM Drive Train Engineer told me once:  "the timing chain doesnt owe you anything after 100,000 miles"
Being that he was one of "the men" in the development of all three Allante engines, I do listen to his advice.

I'm running around 140,000+ on it and I pray at it - a lot.  Engine still pushed that Allante to 110mph just three months ago and held up well.

A full time mechanic told me that an erratic idle where one can show erratic timing is a definite change the chain yesterday.  In my cars, I can pull the D.I.C.  and check the timing while traveling at any speed, so far, she is looking good.

Thanks for the info, i appreciate it. So i guess i should then change it asap, running that high of a mileage.
Is it a big job, to change one of those for this engine?

A timing chain is a big job regardless of engine. The 4100 has some differences in thermostat housing ( depending on car its in) and bolts used to attach the water pump to the timing cover. Do you have a factory service manual? Are you doing this yourself? Do you rank yourself a better than average shade tree? Factory service manual is a MUST if you do this yourself.

Big job? little bit. Year and model?