The Stovebolt Site Forums The Shop Area Engine Shop Air Cleaner and Filter Size Calculations

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.

It's not the size, it's the cfm rating you want to look at. https://www.wixfilters.com/lookup/FilterBySize.aspx Look up the size you want, them look at the cfm rating of the filter. Most all those little filters you see are for lawn mowers. K&N is not where I would be looking. Back when I was drag racing, a friend of ours bought a big K&N for his pickup he was towing his car with. While at the track, he pulled it off his truck and put it on his race car, both 454 Chevys. The race car slowed down about 1/2 second and 4 mph. He reinstalled his Wix filter, made a second run and picked up the HP he lost with the K&N. The K&N went in the trash right then and there!

Reasons #1-10 for disappointing K&N performance
1. too much oil
.
.
.
.10. too much oil

If too much oil, how do you put just enough oil? or is there "just enough".