I have a set of 1971 4 bolt carbs and it seems that my oil level in both never stay full. drive for several hundred miles and check the level and both are all ways just a little below the low mark on the damper plunger. like just above the round brass part on the plunger, is this normal for them to be at that level . thanks 

 My 4 screws always stayed at the mark on the stem. Interesting, I'm going to do a little research. 

 After you've filled the carbs with oil, how much resistance do you feel when you put the caps back on. On mine, I had to push them down with my thumb before the threads would engage. There was quite a bit of resistance. It took a couple of seconds to push each one down. Doesn't seem like much time but it's a short distance.

hi mark ,I have resistance yes but not as much as you have .I fill them just above the inside tube where the dip stick pushes in . [ looking down in]

 The oil level mark is on the black stem between the cap and the brass "jiggly bit" on the other end. Where does the oil level end up filling them using your method?

 Any idea where the oil is going? Is there any oil on the outside or inside of the suction chamber, the piston or the venturi? 

I did not take the carbs apart yet! I fill the oil between the 2 marks on the dip stick so it is between the  low and the high mark. I did not want to take them apart yet as I was checking with other members here to see what there results were. I know if they are over filled the motor will burn off the excess oil and this seems to be where my oil level wants to stay all the time low .the oil I have came from motorsport auto years ago so maybe it might be a little thin? so any way I ordered a few days ago the 20w 3-1 oil  will see if that will make a difference ? probably not!!!!

 It would be a good idea to pull the domes and pistons. Clean them with lacquer thinner and a clean rag. DON'T swap parts from one carb to the other and DON'T bend the needles. Let us know what they look like inside. Pics are better.

yes I will give it a good cleaning and will let you know how I make out  kind regards

Here's a previous thread where we discussed damper oil disappearing:
https://www.classiczcars.com/forums/topic/44049-su-oil-consumption/

Doesn't appear that it was ever completely resolved, but interesting reading anyway.

thanks captain obvious for the follow-up on the old thread . from reading it I will leave my carbs alone as the brass plunger is submerged in the oil and that is where it all ways stays . Bruce made a good point there .