Yep, I'm sure you're all bored of 20XE rebuilds by now, but mine should be taking a while, as I'm going to replace the cams + things, and have decided to drop the block out, so the shell can go to the sprayers whilst I'm doing it.
As soon as I've got my digi cam working again, I'll post some piccies up, but:
I've removed the spark plugs, and they look terrible. Kind of like a brown speccly furr all over the electrodes. The white ceramic bodies have brown discolouration on, as though to suggest they have got seriously hot.
I noticed, as soon as I put the engine in, that it runs about 1/2 on the temp scale, but did not worry too much, as it doesn't have the oil cooler fitted, and it's only got a small rad.
The electrodes on the plugs say to me that it's been detonating at some point, and on all four cylinders, as they're all the same.
I'm was thinking towards a lean fuel mixture, and when I eventually got my inlet manifold off (It's a tight fit in the nova!) I noticed that the vacuum pipe to the fuel pressure regulator had a rather large hole in it, by the manifold. Would the regulator not having a vacuum cause this much trouble?
I'll get some piccies up as soon as I can fix the digi cam. Seems like a sensible diagnosis, but I'm a bit unsure...