( Early Type ) V6 Oil Bath To Paper Element Air Cleaner Conversion

Discussion in 'Early CJ-5 and CJ-6 Tech' started by maurywhurt, May 19, 2017.

  1. May 19, 2017

    maurywhurt Member

    Western North...
    Dec 12, 2009
    This post is a follow-up to Tim E's recent post describing his conversion of the later-type (late 1967-'69) oil bath air cleaner to accept a paper filter element (see V6 Oil Bath To Paper Element Conversion)

    Below is a description of my conversion of an early-type (1966-early '67) oil bath air cleaner to a paper element. I actually completed this project awhile back using a slightly different approach than Tim did, but am just now getting around to writing up this post.

    I've had the original oil bath air cleaner on my early '67 CJ5 since I bought it in 2009, and until recently, I had no plans to change that. Oil bath air cleaners do a fine job of removing dust from the incoming air, and especially considering that it is original to the jeep, I saw no reason to do anything different.


    Then, about a year ago, the engine was rebuilt and completely repainted. At some point following the engine rebuild, when taking the oil bath off or putting it back on, I apparently accidentally tipped it just enough to drip a little oil onto the top of the intake manifold. After the oil sat there for awhile, it had the effect of peeling off some of my brand new engine paint. To prevent this from happening again, I decided to give this mod a try.

    After looking at the air cleaner closely and searching around online for different paper filter options, I was fairly sure I'd figured out a way to make this modification work without altering its original external appearance. However, since I wasn't 100% sure it would work, rather than modifying my original oil bath air cleaner's housing, I looked around for awhile to locate a matching '66-'67 air cleaner. I eventually found one via the classifieds forum on this site (thanks again, honeywells41!) Having both a modified and an intact original oil bath air cleaner is what I'd actually prefer anyway, just in case I or someone else in the future ever decides to change it back to the original oil bath type for some reason.

    The first task was to use a jigsaw / sabre saw to cut the bottom out of the upper portion of the air cleaner housing. Measuring from the top flange of the housing, I left about 1-1/4" of the metal cylinder in place below it. This metal is fairly thin, so it only took a couple of minutes to make this cut. Once the bottom was cut off, there was a metal screen that was easily removed by hand. The cut-off metal edge was smoothed using a hand file.



    The old paint was removed from the lower housing by using various wire wheels on a drill, rather than by blasting. I didn't want to blast it because I was concerned that some of the grit might get caught in between the joints in the metal, get into the cavity, and later find its way into the engine.


    With the upper housing cut open, it was possible to fairly accurately measure the inside surfaces and pick out some different paper filter elements that might work.

    On the Wix Filters website, there's an option to sort through all the air filters they make by their outside dimensions. After carefully measuring and then actually experimenting with a few different filters, I finally settled on the Wix 42011. This filter is rated for 90 CFM, and is very common, as it was used for many years in various Chrysler-Dodge-Plymouth vehicles with the slant 225 straight 6 engine, as well as in some V8 applications.

    Continuing with the modifications on the upper housing, an angle grinder was used to grind the bottom of the PCV tube more or less flush with inside surface of the housing. This grinding no doubt weakened that joint, so after blasting, I used some JB Weld steel reinforced epoxy to strengthen it.



    I wanted to make sure the PCV system would continue to function normally after the original housing was modified. The way the PCV system on the Dauntless works, in a nutshell, is that filtered air is drawn out from the air cleaner through this tube, down through the crankcase of the engine, then out through the PCV valve and is pulled by vacuum into the intake manifold, where the crankcase fumes are burned off.

    One difference between the early type and the later type oil bath air cleaner is that the early type had a cone-shaped bottom flange (see photo of screen removal above), rather than the flat flange the later type had. The solution I ultimately came up with was accordingly a bit different than Tim's.

    Rather than mounting a flat circular flange at the bottom of the shortened upper housing as Tim did, I used a stainless steel ring attached inside the upper housing to provide a level surface for the top of the paper filter element to seat against. This ring also keeps the PCV tube's opening from getting blocked by the top of the paper filter element. Because the ring is mounted up near the top of the inside of the upper housing, the paper filter element used is quite a bit taller in this version.

    The ring is 14-gauge stainless steel with a 8-3/4" outside diameter and a 6-1/2" inside diameter (total shipped cost was about $18 through eBay seller Lumberjack1983). When mounted, there is sufficient clearance between the PCV tube's inner opening and the ring for air to pass through the tube. A small notch was also ground into the inside edge of the ring at the tube to ease the flow of air through it. I used Loctite RTV to seal the outside edge of the ring to the upper housing, then used JB Weld epoxy to make "spot welds" around its perimeter to permanently secure it in place. (After the epoxy cured, I filled the areas in between these "spot welds" around the outside of the ring with RTV.)




    To help ensure a good seal between the filter against the cone-shaped surface inside the lower housing, as well as to get the necessary height differential between the lower and upper housings when installed, I picked up a 5" silicone pipe flange seal on Amazon (Silicone Flange Gasket, Ring, Red, Fits Class 150 Flange: Industrial Gaskets: Amazon.com: Industrial & Scientific). I "glued" this silicone ring to the inside surface of the lower housing using the process described here (which seems to have worked well):
    What glue do you use to glue silicone rubber to steel




    The exterior of the air cleaner housing was painted with VHT gloss black epoxy spray paint. I've used this particular paint in the past and have consistently had excellent luck with it. It requires no primer, and has a sheen that's very similar to the original air cleaner's black paint. (Note, however, that if using this paint and you decide to apply additional coats after the first hour, you'll probably need to wait quite a bit longer than the 7 days indicated on the can for the epoxy to cure completely first....based on experience, I'd recommend waiting at least 2 or 3 weeks.)

    Last, I applied a new air cleaner sticker to match the original, available on eBay from seller jfranzl48, though I believe he sells them through this site as well (PM johns1967cj5).


    The installed modified air cleaner looks identical to the original, and the engine (still) runs just fine with this paper filter setup. I haven't found a need yet to adjust the carb for any differential in air flow there may be between the oil bath and the paper filter element.

    And best of all....No More Drips! :)
    Last edited: May 20, 2017
    ojgrsoi, Hellion and Bowbender like this.
  2. May 19, 2017

    Bowbender I'm workin' on it! Sponsor

    Northern Minn.
    Nov 14, 2014
    I see another project in my future....:cool:
  3. May 19, 2017
    TIm E

    TIm E New Member

    NW Arkansas
    Mar 2, 2017
    Brilliant...very nicely executed sir. I like the silicone ring idea...and that you too kept your original oil bath just in case.
  4. May 19, 2017

    honeywells41 Member

    Auburn, Washington
    Aug 29, 2009
    Way to go Maury. Looks great. I'm happy to be a part of that.
  5. May 20, 2017

    Twin2 wasn't me Sponsor

    Virginia Beach, VA
    Apr 28, 2011
    nice work . still looks stock (y)

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