Crank won't give a full revolution........
 

Please help!
Just put a new alternator damper in and am now re-installing cam chain tensioner. When I turn the crankshaft anticlockwise to align the timing marks, it locks. If I turn it clockwise from this locked position, I can turn it about 315 degrees and it locks again. 315 degrees in either direction and it locks. The cam chain isn't getting caught anywhere. Have I done something wrong when fitting the alternator damper?
Thanks all.

I'd say you've got the timing wrong somehow - it sounds like you're hitting a valve against a piston, especially if it happens in exactly the same place every time.
Look up the excellent "how to" in the relevant section. There are timing marks on the cams which must line up EXACTLY with the marks on the cylinder head.

Good luck with it !

But I haven't got round to setting the timing and the cam chain isn't connected to the cam sprockets while I'm turning the crank.

"the cam chain isn't connected to the cam sprockets"

unless you remove the cams (even if the cam chain is disconnected) given valves will
be down/open in one of the chambers at least

One of the pistons is hitting a valve - don't bend it

Or attach the chain & set the timing

I have removed the inlet cam and am turning the crank with the cam chain NOT connected to the ex cam, so there's no cam rotation.
I don't seem to be able to see the inner timing marks within the 315 degree range of movement I am getting so how do I start timing?
Should I remove the ex cam too?
Thanks again!

Can't remember exactly off hand, but I would start at the beginning.

Remove both camshafts and set the engine to TDC. Read the how to, or the Haynes manual and follow the procedure and pictures to re-fit the camshafts and timing chain.

Start at the beginning and follow each stage, then you can't go wrong, jumping in half-way will only cause problems.

If I can do it, so can you :)

Do not under any circumstances turn the crank until you have removed both cams!! It is ridiculously easy to bend valves. You may ask how I know, and how much 16 valves cost.

As said above when your cams and rocker arms are installed one or more valves will be open. Turning the crank without turning the cams will result in pistons hitting valves. Further advice - before installing your rocker arms make sure the crank and cams are correctly aligned. Then, before installing the rockers turn the adjusting screws out until they are flush with the rocker arm. Don't assume they are set correctly. Now you can install the rockers and set your valves. I assumed and paid.

Thanks guys.
Will remove the second cam and start again!

Thanks DRam.
I've re-fitted the cams and was able to fit the CCT and set the timing.
But...
Let's assume I have already bent a valve or two (or three or four...); how will I know when I try to start her up?

If the valve cover is still off, you can check valve lash/gap. If you find that one has openened up or changed it may be bent and unable to seat. If it does start with bent valves, idle will be rough as hell and it won't rev up very well. One or multiple cylinders with no/low compression will make itself known.