Depending where the pcv is connected (i.e. center carb base plate for me) it is a vacuum leak changing the a/f ratio, potentially affecting smooth idle and part throttle (wot not so much since pcv closed).
For the 348/440, an old style (ribbed), tall, non-bypass SystemOne, with the thinking that filter valve failure or erratic pressure differential of a bypass filter could cause way more damage to the engine than a non-bypass setup.
I have used SystemOne oil filters for a long time on many 'precious' engines, but recommend that one checks the bottom plate element, some SystemOne filters ship with bypass plate others with non-bypass plate.
Sorry for no searching around. It looks like it could work (re. sbc/bbc oil primer tool AND distributor adapter sleeve) according to 4speedman (www.348-409.com/forum/threads/prime-oil-pump-problems.45452/#post-519887). I just wanted to assess if new tools are needed when and if the time comes.
Welcome. On a limited budget I used the Eaton Posi (GM 55P 8.2 Dropout) with the addition of a 4th arm (1959) and Tom Parsons' "Converting non-posi rearend to posi for ‘55-‘64 Chevrolet passenger car"article. All in all a sub $1k mod if you can do most of it yourself.
(@16:58) Isn't that "Positraction" dash trim 1958 only? I remember seeing a picture of 1959-60 "Positraction" dash trim in lieu of the "Chevrolet" or "Impala" trim on the passenger side.
... or thecarburetorshopdotcom or carburetor-partsdotcom or speedwaydotcom.
causes for rough idle and too rich condition could be anything. for air mixture screw ~1.5 turn is baseline.
the photo shows a small rochester baseplate with extended shaft.
Not sure of the color codes but the (Ermine?) white body color with the (Horizon?) blue body stripe complements the chrome/stainless/wheels and the EZI (green) glass so well... a gorgeous car and a beautiful stance, well done.