Ignition timing for 3.9

Hi all,
Just fiddled with the timing on my 3.9 (don't ask me why, it was running nicely!) I set it with a light to 5deg BTDC as suggested in Haynes for a 3.9 high comp with cats, It then seemed a little down on power on both petrol and gas, I now have it set at about 8deg BTDC, seems back to normal, What do you other v8 boys set yours at?

The workshop manual states 6deg BTDC as a base line to start the engine, then with the warm engine at idle speed check with the strobe much the same no doubt as the Haynes book..

Set up as per the book and then keep advancing it until it pinks under load and back off 1 degree.

MGBGTV8 said:

Set up as per the book and then keep advancing it until it pinks under load and back off 1 degree.

Click to expand...

Aye, that's what I used to do with the old 3.5 carb rangey, never had any probs, just wasn't quite so sure if it was ok to do that with cats and lambdas and how much it would upset the ecu, also I found pinking a lot easier to detect on the 3.5, the 3.9 its hard to hear it!