I used to do mine every 40,000 kms, and since I got the car in 93, and from 93 til 99 was my only car (99 to 2012 it shared daily duties with Dolomite Sprint), I did a lot of mileage. Since 2012, I have a "newish" car as daily driver, but Stag gets used regularly when the sun is out. I bought mine with supposedly 90,000 kms on the clock, and have added 330,000 kms to that. So I have done it a fair few times. Every time I changed them, I checked the travel on the tensioners, and was consistent, that is, they had travelled half the distance from the "set them up" posn, to the "keepers" (the tab that catches them if they stretch too far/stops them falling out the end). I always used AE chains as while they stretched (elongated/wore, what ever people want to say, you get what I mean), they were consistent. Once my supplier had none, so supplied me with Rolon chains, and I had to take off the timing cover for something else, and luckily I did, as they had stretched like licorice, almost on the keepers after not very long. Bad batch or "copies??" as Rolon were supposed to be good. Last time I used IWIS chains. Lots of hype and false claims about them. I didn't trust any of them, so I just emailed IWIS in Germany, and they gave me the name of their rep here - in Qld. But before he did, he answered ALL my questions. I called them (QLD guys) and they were good to deal with, and he said they use single row IWIS chains in race engines and they never fail. So I will condition assess mine/use bore scope to check tensioner posn, but I don't drive mine interstate anymore, so don't do the miles I used to, so they should last forever. Each to their own, but that solution works for me.
That's the biggest problem I had! What chains do I replace them with. I read a fair bit of info on forums and Facebook pages about dodgy chains, but I ended up calling James paddock in the UK who were very helpful. I'm just finishing the editing on the next chapter of my stag and the chains, I could of left the job for another year, but didn't want to take the risk of it turning into something bigger! Another shocker is how well behaved the cooling system is on my car. Hasn't drifted into the red on the temp gauge all sumer, but I am changing the coolant from green to red for the higher mix of ethylene glycol, the car came with an additional electric fan and I haven't heard it engage once, as you say in 40 degrees plus the car behaved itself,cheers.
