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Marvel vs Ampco Intake Oilers

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  • Marvel vs Ampco Intake Oilers

    There is a HUGE DIFFERENCE in operation between the Original patented Marvel INVERSE oilers and the Ampco and other simple knockoffs that feed oil DIRECTLY proportional to engine vacuum. People often confuse the two as similar in function.

    An inverse oiler (Only Marvel oilers) feed less oil when the manifold vacuum is high (cruising, idling) and more when the vacuum is less (accelerating, going uphill, etc.)

    Ampco and the other knockoff wannabies are simple suction devices. At high engine load (low vacc) they feed nothing. At high vacc idle and cruising they feed the maximum.

    I have several Marvel oilers (I collect them) and would only run an inverse oiler, never a direct proportional one like the Ampco. If you are using it on an industrial engine with constant speed and load or if you drive that way you may want the Ampco, but those must be mounted lower than the engine vacc connection or with a manual shutoff valve or they may siphon the entire jar into the engine while parked overnight. The Marvel inverse oilers, can be mounted high and do not siphon.

    Marvels were required original equipment with Judson supercharger kits in the 70's or Judson would not warranty the rotor and housing. They were also popular on gasoline engine trucks. Ampcos were often added to industrial stationary engines.

    The Original Inverse Oiler Patent.

    Notice it was issued to Paxton, not "Marvel"

    Now, this just begs the question: Why bother? Just mix the stuff in your gas!
    That all comes down to droplet size and what happens to the stuff. In either case some of it will be burned as vaporized fuel and some deposited on valve stems and cylinder walls. Atomizing it through a carb will create extremely small droplets as the fuel vaporizes and leaves the MMO behind. When mixed in the gas you will get more burn and less product delivery to metal surfaces than with the coarser spattering that a direct droplet feed will provide.

    40 years ago I built and ran quite a few SBC race engines, both strip and circle for myself and others. They all had the metal can (unbreakable) MMO inverse feeders. Never seized an exhaust stem or ripped up a cylinder. More than I could say for the competition. Since it was mostly low vac. & W.O.T. the inverse oiler worked best. An Ampco would not. However, for lots of idling and easy high-vac street driving with little or no W.O.T. the Ampco (which I do NOT collect) would probably deliver a better feed rate profile. So I guess you could say I like the overall concept of both of them.

    Yes, the directions for the Marvel oilers, both initial setup and rebuilding, are online if you search. You can also find pictures of the different styles, both glass and metal can.
    Last edited by MikeK; 12-09-2017, 06:17 PM. Reason: Flunked spellink ang grammah

  • #2
    wow this is really interesting, have never heard of either


    • #3
      Originally posted by tbirdtbird View Post
      wow this is really interesting, have never heard of either




      • #4
        Mike K. I just bought one of these, no idea what is was but it looked neat! Now I want to restore it, any place to pick up a decal? I have the metal one but with a very different filler port, mine has a knob you have to push down and twist to remove. I fond a guy to sell me a new sight glass and some of the gaskets.


        • #5
          Welcome mdoyle7532 to the VFF!!

          3 ~ Tudor's
          Henry Ford said
          "It's all nuts and bolts"

          Mitch's Auto Service ctr


          • #6
            Hey mdoyle7532, WELCOME to the VFF!!
            You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!


            • #7
              Originally posted by mdoyle7532 View Post
              any place to pick up a decal?
              Welcome to the forum!

              Marvels were very popular with VWs and Karmann Ghias. Last I heard there was a guy in Argentina with hundreds of the decals, but that was a dozen years ago and Argentina was, well, a different politic than the present can-o-worms it now is. I'm not so sure I'd send any money there now.

              The decals often show up on "" (a VW site) in their classifieds. Lots of info if you search their posts, too.

              If all else fails, just find an image (try google images) and make your own. I won't tell. . .


              • #8

                Here are the images originally in my starting post for this thread. They were lost to the evil greed of Photobucket. Due to the time lapse I could not re-edit them into the original post.

                For you nubees remote hosting became an early problem for VFF, and Mitch FIXED IT by enabling direct download of images to his site. Thanks Mitch!

                Emerol-Marvel Literature and one model:
                Marvel Emerol.jpg
                Marvel / Paxton Patent:
                Marvel Paxton Patent.jpg
                Attached Files


                • #9
                  Wished I had one of those, would sure fix the problem of always needing to refill my 4oz jar and carry it in the car.

                  That is one thing I will be keeping an eye out for at the June Model T swapmeet.
                  You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!


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