Fuel and Differential Vent Install

Fuel and differential Vent sit nicely on top of the DSE Quadralink crossmember.

Modern muscle cars like the new Camaro have performance and drivability that could scarcely be imagined in 1969, but as technology has found its way into the aftermarket our older muscle cars are accelerating, braking, and cornering so well that fuel slosh, spillage, starvation, and odor have become a bigger problem than ever. A common problem is that under acceleration fuel will leak from the vented gas cap found on many older cars. Switching to a sealed cap eliminates the leak but now a properly designed vent system is needed.

Fuel tank venting is a deceptively complex problem and when improperly executed can result in spillage, fuel pump overheating, tank deformation, “burping” during fill ups, and strong fuel odors. Many resort to running a half tank of fuel and hoping for the best. To ensure we have a steady supply of fuel at all times we equipped our Camaro project with a Rick’s Tank and Vaporworx fuel pump system. Rick’s Tank and the Vaporworx system do not address tank venting, and both Rick’s and Vaporworx recommend our Fuel and Differential vent for this. We’ll be running our vents side by side — one for the DSE built 9 inch and the other to the Rick’s Tank

We’ve already upgraded the rear suspension to a DSE Quadralink, and the beefy crossmember that’s part of the kit is the ideal place to mount our vents since they need a 2.5″ hole in a flat and level space. All plumbing runs underneath the car, and the location needs to be chosen so that any collected liquid in the vent can run back to the tank or differential via gravity.

The gray nylon gasket resides in a precisely machined groove to keep it from being over-compressed, the white washer prevents scratching when tightening the main nut, the gold bit is a 40 micron sintered bronze filter, and the set screw keeps everything in place after installation.

Lots of things to see, but the vents and plumbing are visible in the right middle.

To mount the Fuel Vent we’ll need to cut a 2.5 inch diameter hole, and of all the ways to do this our favorite is the Blair Holcutter. The Holcutter’s shallow and rigid design cleanly cuts through both thin sheet metal and structural steel. As is so often the case, the Holcutter’s upfront cost is higher but it outlasts and outperforms the alternative tools.

Close shot of the Holcutter. The shallow depth, reinforced body, and thick cutting teeth lead to chatter-free use and perfecly round holes.

The Blair Holcutter uses an ordinary electric or cordless 3/8 drill.

After drilling the hole, the vent slips directly into place. The nylon gasket goes on the top, and the polyethylene washer goes on the under side to keep the main nut from scratching the finish.

The vent requires only a single connection to the tank or differential. We recommend flexible hose since strap-mounted fuel tanks can move around a little bit which could cause a hardline to eventually fail.

The fuel vent is on the left, connecting to the fuel tank in the foreground, and the differential vent is on the right with its vent hose connecting to the rear end axle tube.

We use PTFE hose for all fuel-related applications because most brand-name aftermarket AN-type hose allow gasoline permeation (smell) but worse, will get brittle and eventually fail in a year or two. We really like the PTFE/Kevlar braided hose from Pegasus Racing because it has an almost unlimited lifespan, is lightweight, flexible, emits no smell, and hose ends are easy to install. And, not that it matters, but it’s good-looking too, with a classy green-gray hose and silver and black hose ends.

The Pegasus Racing hose and hose ends are stylish and easy to fit, plus provide a nearly infinite lifespan. The 90 degree 9/16-18 to 6AN ORB fitting (upper left) is from Earl’s.

The Rick’s Tank with the VaporWorx option has just two plumbing connections: the main fuel hose and the vent. The Tank vent itself is located in the highest point of the tank, and is routed to the 1/4″ pipe fitting welded to the front face of the tank.

The Rick’s Tank comes with 1/4″ pipe fitting, making connection to our Fuel Vent a snap.

Announcing two new vent products from II Much Fabrication rounding out the II Much Vent Product Lineup. From left to right is our original bulkhead mount , the new side mount, and side mount with integral filtration.

UPDATE (23March13): Announcing two new vent products from II Much Fabrication rounding out the II Much Vent Product Lineup. From left to right is our original bulkhead mount , the new side mount, and side mount with integral filtration.


To place an order, please visit the following link. We usually ship the same day.

Fuel Vent Webstore

9 thoughts on “Fuel and Differential Vent Install

  1. Pingback: II Much Fabrication

  2. Our vent needs to be oriented as indicated in the installation article (vertical though a few degrees either way won’t hurt) and above the fuel tank. The plumbing that connects the tank to the vent needs to be routed so that it doesn’t trap fuel with a low spot.

  3. John I’m interested in purchasing your product , can you give me some details please. Will it vent a tank flowing enough fuel to support 650-700 hp. does it have rollover protection or does the tank need one, does it have carbon filtrate like oem for fuel odor elimination ,lastly does your unit separate liquid from fuel vapors.I am modifying stock nova tank with sump and weldon pump ,not sure how high i can weld vent fitting on tank having stock floor pan. Does fitting have to be above fuel level to work? Thanks for your help.

    • Michael,

      Thanks for the enquiry!

      Our vent system will flow enough air for 1500 hp. 700 hp is no problem at all. The vent does not have roll-over protection: if you require that, you’ll need to incorporate it into the plumbing between the tank and vent.

      Our vent does not have any carbon-based filtrate (aka activated charcoal). Such systems require purge plumbing and ECM support. Our proprietary design captures gasoline liquid and vapor and allows it to return to the tank, eliminating fuel odor and spillage when used with a non-vented fuel cap.

      Finally, yes, your tank vent port must be above the fuel line (ideally on the top of the tank) — otherwise you can induce a siphon effect through the vent. That’s true of any vent system, not just ours.

      John Parsons

      II Much

  4. I have a 68 Camaro and live in California where they have the vapor recovery nozzles at the gas stations. No matter how slow or what angle I try to fill my tank I always get fuel spewing out of the filler neck. I was going to weld a bung to the top of the gas tank and another to the top of the filler neck and connect with a hose to hopefully resolve my filling issues.

    I saw your fuel/diff vent and was wondering if it would resolve my filling problem.

    My other concern is fuel smell. I see that your fuel/diff vent has a 40 micron filter but was wondering how that would keep the fuel smell out of my car and garage.

    Finally in your experience with 1st gen Camaros what would be your recommendation for the location of your vent if I don’t have the DSE crossmember?

    These small but frustrating issues have been a thorn in my side so any assistance you could provide would be greatly appreciated.

    Thank you,
    James Vergopia

    • Hi James,

      We’ve not tested our vent with vapor recovery nozzles, but we tested it on several cars here in Florida. Our vent does help with those burping issues, and vehicles equipped with our vent are much better behaved during fill-ups. No burping or premature shut-off.

      I can absolutely say that our vent will help with fuel smell in your garage, though some of it may be coming from your fuel hose (especially if you use typical mail-order AN hose). If you aren’t using hard-line and and PTFE hose for your fuel system, you should be.


      You can locate our bulkhead vent in the same location of the car without the DSE crossmember. It will be a couple of inches lower, but will work fine. Just find a decently flat spot in that general area. If you’d prefer, our new side-mount vents might be a better packaging solution.

      Good luck, and don’t hesitate to give us a call: 301-814-5322.

      John Parsons

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    Rate This ThreadCurrent Rating Excellent Good Average Bad Terrible DisplayLinear ModeSwitch to Hybrid ModeSwitch to Threaded Mode03-19-2013, 03:15 PM #1 JohnUlaszek
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    Pro-Touring.com Sponsor Join Date:Aug 2004
    Posts:575 Two new Vent Products from II Much Fabrication
    Announcing two new options for venting from II Much Fabrication which round out the II Much Vent lineup. Although our bulkhead mounted vent is still the simplest option for fuel or diff venting, requiring only one hole and one hose for installation, it’s not suitable for every configuration. These new vents are priced at $199.00 for in-car mounting (using an external filter), and at $209.00 with integrated filter for under-car mounting

    Both our new vents are in stock and ready to ship.

    Please head over to http://www.iimuchfabrication.com for more info and to order.

    Left to right — our original bulkhead mount design, side mount, side mount with integral filter.


    $209.00 Last edited by parsonsj; 03-19-2013 at 03:24 PM.

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    Today, 01:07 PM #2 68 SuperRam
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    Registered User Join Date:Dec 2002
    Location:New York
    What type of filter could you use for “in-car” mouting option. Like a K&N value cover filter – running from your product monuted in the trunk with a hose to go under the trunk floor pan?

    I would consider using on my Fuel Injected Rocky Valley Tank – no vent in tank – but have a vent on the filler neck – Ridetech gas cap and filler neck. A small hose run down the filler neck below the trunk pan to vent the tank – but gas smell is very strong.

    • Hi John,

      I like the K&N 62-1320 for a filter with our “in-car” vent. You would need to connect the vent port from the filler neck to our vent, and then from our vent to the remote filter.

      Let us know if you have any other questions.

      John Parsons

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