I have been watching some tv and seen some of the mud runner trucks that are carburated and they have a foam filter that goes around the regular air filter. I tried looking on the internet and couldnt find anything i was wondering if anyone knew what they are called or where you can buy them. My truck is a 78 with a 400.

 

Summitracing has them. K&N sells them also. I used to run some of that eggcrate foam during the dusty season and it worked well. Cheap and easy to get.

 

K&N makes two kinds of pre-filters. Airforce 1 which is a red open cell foam similar to what Truflow uses as a primary filter and then they have a pre-screen which is pretty much pantyhose that you slip of the filter.

 

I looked at summit and i was looking at the k&n foam filter and that pantyhose slip on thing. I was thinking since i have a 4 inch paper filter right now i was going to get the summit 6 inch cotton filter which looks like a k&n just cheaper then get the foam and pantyhose filter things and put both on and the extra 2 inches would make up for restriction even though the foam filter and pantyhose thing only restrict airflow about 2% each, and so when i go mudding i wont have to really worry about getting water or mud clogging up the filter.

 

The pantyhose is more for dusty conditions and does it's best work while touching the cotton gauze filters because of the tiny amount of oil it steals. The oil on the pantyhose acts like the filter. The open cell foam is more for the mud environment, it catches and slows larger particles. If you want to try both, I wouldn't stop you, but the open cell is more for your application.