The Stovebolt Site Forums The Shop Area Engine Shop Oil bath air filter to paper conversion

I know there a tech tip or two on the “how” to do this. I’d just like to hear from some folks who actually ran the original oil bath and later modded it to accept a modern paper element....

Would you do it again? Worth the trouble?

Any difference in how the vehicle ran? (More or less restricted)

Anything you’d do differently?

I've gone to paper twice. First, it was the Carter W-1 carb with a 235. I used the base from the oil bath setup, found a Fram that fit and topped it off with a cake pan. That's the kind of thing the rancher in eastern Montana would do in the old days. Not everyone would want to emulate him (or me). Picture 1.

When I went to a 261 with a Rochester Monojet carb, I got an air filter from the junk yard which would fit the larger throat of the Monojet. I then got a Mr. Gasket air cleaner that was the same overall diameter as the bottom and used just the chromed top. Picture 2.

(Some are shaking their heads at the messy look of my engine compartment.)

Resourceful!

Wally's 261 air filter looks to me to be plenty of air filter surface area for easy breathing.
As far as the the 235 filter, if the element is twice as thick as the air filter on the larger diameter one on his 261, I'd say that would be good to go too.

The Series 6000 2-pound oil-bath air cleaner has a replaceable element.
Replace it with a modern filter with diameter and height approximate to the original element.
Choose a filter with a CFM rating higher that what is needed by the carburetor.
No modifications required.
Fits on carburetors that do not have the center stud style (1960+).
It may look big and bulky but it is practical.
No noticeable affect on engine performance.

Paper filter: WAY better flow. WAY better filtering. Worth the trouble of not having to dump out the old oil, clean out the element with kerosene and refill. May run a little better and have a h-air more power.

nice one

I did the same conversion as buoymaker after noticing my idle drop by ~20rpm while installing the original oil bath. (it was probably dirty)
Paper filter doesn't drop any RPM. I'd be interested if anyone else noticed this.

jw51 I just make a whole air cleaner out of 1/8 aluminum plate easy,tight,safe. Buff it you got it. Also will work good on dual carbs.

That looks WAY easier than trying to hack up the smaller one. I shall be looking for that model filter housing.

I replaced the entire element with a Fram CA148. Fit great and was simple to do. This is on my 49 3100 w/216

I did the paper mod on one of the pancake filters. I cut off the original bolt and then used a longer bolt of the same diameter. I added a nylon insert lock nut to keep the new bolt in place. The longer bolt is required because the filters that were available online were taller than the original wire mesh. I added an appropriate size wing nut on top. Pic attached.

I can't tell you if it affected performance, as I've never used it. The carb on the later 235 I'm going to use has the center stud, so I went with a later style filter. Sacrilege, I'm sure, but I always liked a snorkel style filter.

If you could find a paper filter at least twice the height of what is on that pancake filter, it would likely breathe the same volume of air as the original mesh filter.
The current short paper filter may well breathe fine as is, but it won't take much dirt to reduce the airflow below what is acceptable.

As the author of the mentioned tech tip, I can report that a couple years and hundreds of miles down the road, it still works exceptionally well, even with the small "tractor" filter I used. I have driven the truck "open air" and have not noted any differences.

I use the original base and cap on this 1950 3100. It is a NAPA Gold 2375 air filter (6"x2"). NAPA 2373 also fits perfectly.

As 52Carl suggested. During my conversion, I started out with a K&N filter of about 2" in height. I then found another K&N filter 1" taller. Rpm at idle went down a little.
Runs great.

If one can get cool outside air rather than hot air preheated by the radiator, engine will be more efficient and less chance of pinging when under load. It will not look exactly original, so if that is ones goal, keep it original.

Ed

A Fram CA-148 paper filter fits the stock oil bath air filter element.

I scavenged one off of a slant 6 some time ago...paid $5 for it, and it has worked great. Filter elements are $5 or $6 depending on where you buy them.

Jon, will that fit a carb with a clamp-on style air horn?

Wally Montana Don't worry about messy engine compartment,if it works your doing good. You ought to see my mine,9000 miles since 2018.

Otto You hit a nerve then,found that exact filter in the barn-gonna get a NAPA element (or two and fix-up one of those filters). Don't quite trust the oily aluminum foil element !!

That's funny.

The truck breathes great with this filter and no loss of RPM as others have asked about.