I have been testing various carbs and air filters on my 235 this spring. One thing I have learned the hard way is these 235s require more air than the tiny universal chrome cleaner/filters that you can buy for 1 bbl carbs.
There is a calculator here...
https://www.onallcylinders.com/2013/11/27/match-air-filter-size-engine/Basically if you run a 6-1/2" air cleaner you would need a 2.5" high filter. *BUT* K&N company testing has revealed that you want to maintain a 1/4 to 1/5 ratio of diameter to height for best results. So a 9"x2" or 10"x2" would be best.
Prior to running these calculations..... Due to hood height issues on my 56 210 sedan I tried a 6-1/2 x 1-1/2 filter. The engine was not happy and stumbled at high RPM. I took the lid off the air cleaner and it straightened out immediately.
