You'll probably want to do this the first time you change your plugs and leads, there's significant HP recovery that can occur if your old parts are worn out. Also, it seems it might be worth the effort of changing to a fresh coil at the same time
(thanks Reaper)
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Thanks to whiteknightVR94, here`s some tech info for the 5.0L.
Firing order: 1-2-7-8-4-5-6-3
Spark plug gap: VR/VS, 0.8mm - 0.9mm. VN,VP,VQ 0.95mm - 1.05mm
Spark plug type: AC R42LTS (geuine holden) although they use Nipon for all EFI commodores now
Ignition timing: 10 degrees B.T.D.C
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I had a much more detailed write-up but the bloody thing crashed on me right as I was about to submit it .. **rage** I very nearly didn't bother doing another one, but since I'm a nice person, here we go!
You'll need:
- new dizzy cap
- new rotor
- screwdriver
- sandpaper
- hammer and a foot or so bit of wood to tap something with (I used 2 hammers
)
- whiteout or black marker - depending what colour your leads are
1. Number all your leads. Write each number twice in case one rubs off. It doesn't matter how you number them as long as you can remember. Take a photo if you have to, you don't want to put your leads back the wrong way around. Remove your numbered leads and stash them off to the sides out of the way.
2. Undo the 2 clips (same as the ones on your factory airbox) holding the distributor cap on. One of mine was stuck, hence the screwdriver
3. Remove the dizzy cap - you'll need to pull the hoses out of the way, it's tricky to get out.
4. Pull the rotor button off, if it's tight just pull harder and wiggle it around if you have to.
5. Sand back the opposite side of the shaft to the cutout, this is where the metal contact will be. Only really necessary if it's rusty, like mine was, you could probably get away without doing it at all, really. I just did it because it seemed..... better.
6. Instal your new rotor button, taking care to line up the cutout in the metal shaft. Use your hammer and bit of wood to give it a gentle tap once you're sure it's lined up OK. Don't have to tap it if you don't want to, I just wanted to make sure it seated right.
7. Instal your new distributor cap. The metal clip locations will give you the 2 ways this could go on, only one way actually works. Try each of the 2, twisting it around to see if it locks in.
8. Clip the cap into place. If the clips don't engage, your cap isn't located properly - try step 7 again. If that doesn't work, try taking the rotor off and doing that step again.
9. Replace all your numbered leads, ensuring they go on the same way as they came off, or your engine will hurt badly when you start it up.
10. Have a look at the poor condition of the old parts and be happy that you've done this job.
11. Fire up the motor, listen to the smoothness. Enjoy knowing that you've restored a few lost HP, or that your efficiency will now be that tiny bit better, whichever you prefer.
I noticed the difference immediately, the straight-cut timing gears on my 5L made it very obvious when the idle RPM fluctuated.... not any more
It runs much smoother now.
Hope this helped some people
Sam
5L EFI - changing the distributor cap and rotor
Now on Gas and costing 11c a Kay!
Always glad to help and B helped 
but no, I had the flathead sitting there, ready to go!