The compression is pretty much spot on, so Ive ruled out the head gasket. Ive put the standard header tank back on, re bled the system, and its still the same. Ive recently read that the stat housing is self bleeding, and may take several days to sort itself?
Ive also learned that the different coloured temp senders have different resistance, are were matched to the clocks back in the day.
If thats the case, I need a beige/creamy coloured one instead of the new red one ive just put in.