hi,should there be a o ring seal on the spray bar pick up between head and bar where it pushes into head? cheers.

Short answer. No.

yes

I just replaced mine and the old spray bar didnt have one and the new one didn't come with one. Not to that it should have one. Car been running now and no dramas

Lachie

OK, 2 no and 1 yes!!!!!!!!!!!!!!!!!!!!!!!!!!!!

That equals a maybe... yeah?

Yes

yes

the yeses have it......

Yes - it will help seal the oilway and maybe (ever so slightly) improve oil pressure...
Had an engine in the motorkhana car about 10 years ago with the spray bay come loose (the bolt just below cam loose) and the oil pressure was very bad at idle, as the pressure was escaping at this point..... Did the bolt up and hey presto - oil pressure restored...
 
They may or may not seal well without one, but will definately seal better with one...