Are the tri-power foam air cleaners not considered very efficient?
 

I've been reading up on air filters. We currently have reproduction foam air cleaners on the tri-power. These foam air cleaners don't get a very high rating for stopping dirt. I re-oil them every Spring. We've only put about 500 miles on the car in the past 4-5 years so they aren't getting dirty. But, if the foams aren't all that efficient, I could get paper filters and save the foams for car shows or whatnot.

My 64 GTO came with foams.
I tested foams vs paper filters (street driving and at the track) and foams did nothing for the performance. Think the foam support rings were actually blocking airflow to the carbs.

From that point on, I bought the NAPA paper filters. The K&N filters are supposed to be better vs the foams.

Tom V.

The issue with the foam filters isn't performance, it's maintenance. I found them to be a big pain.

1st, design no lip & glued seam or 2nd. design with the top & bottom lip & heat sealed seam ?

Ours have lips at the top and bottom, I've seen no issues with the seam splitting. We got them from Ames if I remember correctly. These are the ones with the part number embossed into the foam but not with the AC. Reoiling them once a year doesn't seem to be too much maintenance and they seem to be holding up well. In this conversation I'm only concerned with how well they do or don't filter out dirt. As an example, I've removed K&N filters from my other cars (Chevelle, Chevelle wagon, truck) since it turns out they let through too much dirt. And funny thing, my L79 actually runs better (better vacuum secondary function) with a quality paper filter than it ever did with the K&N. Unfortunately I still have a K&N filter in the aftermarket intake on my 2006 GTO as it is kind of a custom fit and an equal paper filter won't fit in the intake. I've been looking at Green Filters (work like a K&N, an oiled filter) but I assume they are no better at filtering out dirt than K&N is. The daily has a dry washable filter that appears to do a fantastic job of filtering and lowering restriction but that company doesn't make a filter that would fit in the DuSpeed intake on the modern GTO.

On the old GTO I'm not really worried about squeezing the last iota of performance out of the tripower, I've mostly concerned about having it run well for the long term and by ingesting dirt it's life would be shortened.

After dealing with restricted paper filters on my daily driver '65 for a couple of years, I switched to K&N about 1984. Same set has been on the car ever since. Driving the car a lot with the paper filters, the center carb filter would get restricted very quickly due to its small size. Today, on a car driven less than 5,000 miles a year, this would probably not be an issue.