Evening all....I've had a good search but not found the answer, so here goes: on my 3.9i (out of a Disco 1 originally, it's now in my 90 with the auto box behind it) the only timing mark, on the balancer rather than the pulley itself, is a groove/channel about 5mm wide. There's a pointer mounted on the engine case. If I stick a timing light on it, it shows the groove when the light is on cylinder 1 so it's the right sort of area - but not very precise!

I can adjust it by ear, I know, but would be good to know what the pointer/groove is telling me. For example, is one side 0 degrees and the other side 5 degrees? (as per the manual; I can see that a lot of people run more advance and I'll play with that).

Just working through the basics currently, it seems to lack a bit of power on the motorway, ie, it'll cruise at 70 OK but on a decent long uphill it slows down unless I drop a gear, and sometimes it feels like it just loses some (not all) power and will then pick up again. So we're starting with ignition - new cap, arm, leads and plugs to go on.

Thanks.

That's no gonna work! The timing marks and the slot in the balancer are two different things. You need to properly clean (scrub) the bottom pulley, I would suggest a good degreaser and a small brush - like a nail brush and you should uncover the timing marks. They are not very deep and are easily obscured by a long term build up of dirt. Once cleaned and visible, you can improve the timing marks by painting over them with white or silver paint and while the paint is still wet, wipe over with a cloth so the marks hold the paint but the surrounding part of the pulley is clean. HTH

^^^^^ This.
To avoid all doubt remove No 1 plug & the nearside rocker cover.
Using a long rod in No 1 plug hole turn the engine in its normal running direction until No 1 is on the compression stroke (both valves closed).
The rod will enable you to determine when the piston is at the top of its stroke. If you go past turn the engine back until the piston is well down the bore then bring it back up again - taking it well down will allow for any slop.
Once you've got it check the timing marks on the pulley against the pointer.

Thanks both. I wrote this before the other posts about the starting problems, my intention was to change the cap and arm and check the timing (as I've never done so, just thought it would be prudent to!). I'll do this once I get the damn thing running reliably again. I've done the white paint trick in the past on other cars, helps a lot!

Rather than a rod, use a DTi with extended fixed rod for accurate tdc positioning. The RV8 can be difficult to set up without the proper equipment including a strobe that measures dwell angle, this is very important. I can recommend reading Des Hamill's superb book, How to Power Tune Rover V8 Engines

www.amazon.co.uk/Power-Rover-Engines-Track-SpeedPro/dp/1903706173

There's no need to adopt of the rebuild tuning options, but the ignition timing section makes very clear how to set up an RV8 properly + many replace the near non-marked crank damper with a marked viscous harmonic balancer which enables clearer crank timing. Google RV8 harmonic balancer