Cam chain wear

I'm adjusting my cam/timing chain. MKIII has 29,000 miles on it. At it's tightest point on the top of the chain there is no slack but there is still slack on the bottom. At it's loosest on top the chain has a good 1/4" slack. I'm guessing the chain should be replaced.
Opinions please.

You have to watch out for the valves and the springs as they will act to transfer the slack from the top to the bottom of the chain depending on whether they are opening or closing.

Pete,
While you have got the chain almost off you could change it, but you could adjust it especially if the slack is the same all round. The chain tightens at the top because the valve springs are now trying to push the cam and turn the crank.
There are numerous ways to adjust the chain. For me I find the easiest; Set the chain with the tight spot at the top, slacken the adjuster and put a finger on the top chain run and thumb under the adjuster and gently squeeze them together. Tighten the adjuster. Turn the motor until the chain slack is at the top and check it has 3/16" total free play. For me it usually has but you may need to readjust.

Dave

3/16" at tightest spot. Rotate the engine in several positions to check for tight spots. Can be a little tighter if you are using a rubber footed cam chain adjuster. I think Mrk.III came standard with these. It also should be adjusted with a cut away timing cover or INTERMEDIATE SHAFT SUPPORT PLATE TOOL (AKA pre-Mrk III) so it will get the proper tension of the chain when it is all buttoned up. You might be able to do it with the mark III cover on but I am unfamiliar with Mrk III's so L.A.B. will probably correct me. again Like cash said at 29,000 you should probably change it. I like the Iwis chains from the chain man. https://the-chain-man.co.uk/
Seeing that you are in the USA you can ask comnoz as I know he carries them.
Cheers,
Thomas

I think judging from the slack on the bottom the chain is shot. Seeing as i just rebuilt the head I may as well.

Pete,
This is from the workshop manual.
+1 Thomas, you need to use the support tool to get a good measurement.
Pete