The only thing I can think of is that you have slack in the chain after tightenING the cam bolts. Are you applying slight pressure on the cams to the opposite direction of tightening. This will take the slack out of the chain.
Follow procedure in "Engine repair course code 168". You can it at jagrepair.com

 

After going to jag repair.com and investigating tool rentals there was a short summary addressing my concerns on procedure. Namely that if the locking tools were in place and slack removed from drive side of chain, upon removal of the cam locking tool bank A or passenger side would slacken and result in the cams no longer in exact alignment with each other, but to no detriment.
Does anyone have a timing chain tensioning tool for lend or sale. The one that came with the kit I purchased on eBay, failed out of the box. One of the 2 pins fell out.

 

This is what I would do if I were in you situation. I don't know which tool you lost the pin in, VVT or exhaust cam. If you don't have the one for THE VVT intake cam take a strap from a ratchet tie down and wrap it around the VVT a couple of times. Have somebody else put tension in a counterclockwise direction on the cam while you tighten the bolt. You might be able to do it by yourself. You don't need a ton of force, just enough to keep the sprocket going clockwise wile your tightenING the bolt. Check the chain when your done to make sure it's tight. It's possible that the right size oil filter wrench might work.

If you don't have the tool for the exhaust cam you need to use a little enginuity. I would first try to put bolts in two of the holes on the sprocket and use a screwdriver to put counterclockwise tension on the sprocket while you tighten the nut.

If my ideas are a not very smart I hope somebody will correct me or maybe they might have better solutions.

If all else fails I can loan you my set.

In the photo the VVT is still on. I didn't feel like taking it off but this gives you the idea.

 

Today I got the Jag back together, off the jack stands and save for the bonnet still off looking like her old self. Then I tried to start her. Seemed like little or no compression. So I pulled the spark plugs and used a teaspoon of oil in each cylinder to combat bore wash and was hopeful when I got a positive response. Close but no bananas. I repeated this process one more time before calling it a day. Time to think and time to fully charge the battery. The second time was much like the first. Sounded like compression was back up and almost wanted to start. I remain hopeful but if anyone would like to chime in, I would welcome your imput

 

did you pull the fuel injector fuse before cranking? Also, if the engine sat for awhile it may take some cranking to get er oiled up.

Check your compression to see if it is up to par before getting too bummed.

 

So in an attempt to reassemble the timing chains and tensioners on my 2000 xj8 I have broken the VVT cam sprocket bolt twice now. Its the one on the intake cams with the passage clear through for oil passage. My workshop manual states 112 to 125 nm for all four cam sprocket bolts, even though the ones in the end of the exhaust cams are not hollow.
I have yet another new one ready to go but I just wanted to check to see if I am missing something. Its broken twice right around 80nm.