The Smog Monster: California’s Catch 22


How to Replace Filler Pipes Before Your Next Smog Inspection

Some months ago, I purchased my first MGB. It was a case of the right car at the right price and in the right condition. (Or so I thought!) I went about replacing all the missing smog equipment and repairing the Lucas wiring (of course). The wiring was a mess, courtesy of a guy who’s idea of an electrical connection was a quick twist and, if I was lucky, some tape. (Most of those were poor connections too.) But that’s another story! Most of the smog equipment was in a box, thank goodness! (Has anyone priced that stuff lately?) Just bolt the equipment back on and replace some hoses, brackets, and lubes and be done with it, right? Wrong. Remember. Murphy’s Law applies to British cars too.

When I’d finished getting the hardware boiled back on and operating properly. I took it to the smog inspection station to have it tested so I could re-register it (required in California). I had missed one small thing and was told I couldn’t even have it tested until I fixed it. The restrictor in the fuel filler pipe was missing. (It has a smaller hole that will only accept the unleaded gas pump nozzle ) I guess a lot of people have popped this little thing out so as to run the cheaper leaded gas. (This is not recommended even without the catalytic converter, because the engine runs best on 91 or better octane and most leaded regular is only 89 octane, so the engine knocks). I searched high and low for the pipe with the restrictor in it, new or used … nothing! In speaking to Bob Cote at the Moss Motors order desk, I found that Moss has been looking for a proper replacement fill pipe of this type, without success, for some lime. Bob said he had six or so people wanting one if they were able to find it. For those restoring a car to original this isn’t the answer, but for those of us happy to get past smog inspection and onto the road it will do the trick.

There is a repair kit for filler pipes, and it exceeds EPA requirements. It is acceptable, at least in California for inspection purposes. It is a “Universal Gas Tank Restrictor” (NAPA part number 730-2323).The kit contains an insert for the fill pipe and LOC-WELD (an epoxy compound) to secure it in place. I located it through the California Bureau of Automotive Repair, the agency that runs the pollution control program. (Yes, Virginia there are helpful bureaucrats!) It does not come with full instructions for the LOC-WELD product, so I will cover that here.

To install it, remove the metal fill pipe from the rubber tube leading to the fuel tank. (A spot of silicone lube helps to get it through the rubber grommet in the body.) Cover the rubber tube with a piece of plastic and secure it with a rubber band or string, to keep small children, curious cats, and crud out of the tank and the flammable fumes in. Wire brush and clean the inside of the lube of all rust, grease, and other crud (It is very important to do this right, so the epoxy slicks and you don’t end up trying to fish it out of the tank later). Bend the tabs to fit snugly into the pipe from the tank side. Position the restrictor in the pipe, making sure that the gas cap will still go on with the restrictor in place. This is important because when cured, the epoxy forms a 3000 psi hold so it’s hard to fix mistakes later! Mark the position of the tabs with a pencil. The hinge part of the restrictor should be to the top of the fill neck (most pipes arc marked with TOP). Rough the labs and mounting places in the tube for the tabs with sandpaper for a good bond. Mix equal amounts (about 1 1/2 inches of each) of the epoxy and hardener to an even gray color. You now have 4 to 6 minutes of working time to get things positioned correctly. Using a small dowel or a small flat-bladed screw driver that has seen its better days, coat the previously marked spots with an even coat of the mixture and place the restrictor in position. Now add more epoxy to form an even coat over the labs and out onto the wall of the lube. Additional epoxy can be used on the down tube side of the restrictor, just to make sure. Clamps are not necessary if the tabs were correctly bent for a snug fit. The LOC-WELD will set in 15 minutes and cure to a 3000 psi bond in 16 hours. Let the assembled parts cure overnight to be sure maximum strength is achieved. Remember you will be poking it with a gasoline nozzle many times in the future, and you don’t want to knock it loose and into the tank!

The LOC-WELD product, when purchased separately, comes with more instructions than come in the kit. LOC-WELD is toxic if swallowed, the fumes can be hazardous, and it is somewhat flammable, so use it with proper ventilation and caution. It will stick almost anything to anything else, so don’t get it on clothes or skin (remember your first experience with super glue!) If you have not used if before, I strongly recommend that you read the full directions on the LOC-WELD package at your auto parts store before proceeding.


By Jon Sorenson

  • LOC-WELD and LOCTITE are registered Trademarks of Loctite Corporation
  • NAPA is the registered Trademark of Napa Auto Parts

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