Right ive got a xr3i(mfi) and its blowing blue smoke out the back. Ive changed the valve stem seals twice and also done a compression test which came back as
Cyl 1 - 149
cyl 2 - 149
cyl 3 - 148
cyl 4- 150

so there all way within tollerances(they were done when the engine was warm btw)

Any other ideas?

 

have you checked the engine breather isn't blocked?

compression may well be within a good tolerance but the oil scrapper rings last one on the pistons could be worn which is allowing oil to pass by!

 

Yup checked all the breathers out.
Some more background:

This all started after i changed the headgasket(tho ive done this a million times). However on this build i replaced ALL the valves, as i had one slightly bent and thought i may as well do the lot for peace of mind. However i never replaced any of the guides. Would this be cause for concern? I dont know how much CVH guides wear? There is minute play in each valve guide...

 

As said, just because compression rings are good(?) it does not ALWAYS mean the oil control ones are.
I would also as said check the breather system.
tabetha

 

I dont think those compressions are that good actually!! My turbo lump has higher compression than that (turbos being low compression in comparison to a N/A)

As for the comments on pistons rings..........a lot of people dont realise the second compression actually serves more as oil control than compression, and is usually an L shape to act as a scraper