How To Pass Emmissions Testing - 4-Wheel & Off-Road Magazine

Fred Williams Brand Manager, Petersen’s 4Wheel & Off Road

If you live where there is no smog testing, this story will either bore you or humor you with all the crap we have to deal with. If you live in a smog-check state like us, all we can say is good luck, it’s a pain if you own an old truck, maybe start looking for property in one of those less stringent states.

bluferd Blew Smoke 1979 Ford F 150 Getting Smogged Photo 39525636

The carbureted colonoscopy.

Our ’79 Ford F-150 known as BluFerd unfortunately misses the 1975 cutoff for no smog testing in California. Because we bought it out of state, many of the smog parts had been removed, but we wanted to drive it, so we decided to see just how much work is required to bring it up to spec. We admit that clean air is good, but as these vehicles age, the required smog components get harder and harder to find in working order, and few are being reproduced. We wish our state would go back to a rolling 20- to 25-year-old smog life, but that doesn’t seem likely any time soon.

PhotosView Slideshow BluFerd has a 351M motor and is a California smog-equipped vehicle, meaning it requires the most stringent of components to get past the visual check and tailpipe sniffer. There were also federally approved smog vehicles, and these often had less stringent components. Finding the small Vehicle Emissions information sticker under the hood verified that it is a California smog truck. Bummer.

BluFerd has a 351M motor and is a California smog-equipped vehicle, meaning it requires the most stringent of components to get past the visual check and tailpipe sniffer. There were also federally approved smog vehicles, and these often had less stringent components. Finding the small Vehicle Emissions information sticker under the hood verified that it is a California smog truck. Bummer.

Also under the hood is the Vacuum Hose Routing sticker. Ours is on the hood, but some are on the valve cover. This will be very important as we begin rounding up the spaghetti of vacuum hoses to make it run clean, but first we started with the tailpipe.

The exhaust system BluFerd was fitted with sounded good but was missing a few requirements, such as a catalytic converter and a muffler. We towed it (you can’t legally drive a vehicle without proper smog equipment) down to Chappelle’s Kustoms for a new smoke pipe.

A catalytic converter from Walker Exhaust had to be installed since the original had been lost over the years. The catalytic converter takes exhaust gas and reduces carbon monoxide, oxides of nitrogen, and hydrocarbons by flowing them past a catalyst and through a ceramic honeycomb. This causes a chemical reaction to that reduces the bond of the offending chemicals, creates heat, and results in less contaminates in the outgoing gases.

Behind the cat, a Dynomax muffler simmers down the exhaust tone, though it does little in the actual emissions category compared to the cat. The 6-inch-round, Ultra-Flow muffler has a straight-through design with sound-deadening fiberglass that is spec’d up to 2,000 hp. That ought to cover our tired old Ford just fine.

We headed to Ace Auto Care in Atascadero, California, for an initial smog inspection. They determined that BluFerd would require an air pump and a check valve, so we sourced them through LMC Truck.

The air pump or smog pump or secondary air injection, as it can be referred to, is a beltdriven pump that feeds additional air into the exhaust system to help the catalytic converter “burn” the unburnt exhaust gases. The 351M in BluFerd received a new LMC check valve in the intake manifold to feed the exhaust system. Some smog systems pump the air directly into the exhaust pipe. Air pumps are no long used on new vehicles and are considered horsepower draws.

After securing a new exhaust and air pump, we looked at messy stuff: all the vacuum hoses, valves, and switches. The vacuum hoses are a very primitive computer that controls your engine’s emissions. It does so by noticing the vacuum pulled as engine rpm increases and the heat of the engine, and then opens and closes valves accordingly. For example, the Exhaust Gas Recirculation (EGR) valve opens and allows exhaust gases to reenter the combustion process to reduce the compression temperatures and thus reduce nitrogen oxides. Because EGR valves cycle exhaust gases, they often become dirty and need cleaning or replacing.

Another nearly impossible part to find is the load control valve that senses vacuum load and then opens a secondary valve. If you have an old truck with all these smog parts still on it, you may just want to put them on eBay because someone in our state is probably looking for them, though technically you are not supposed to remove smog equipment of any type.

BluFerd also has a variety of shapes and sizes of vacuum reduction valves. These have varying sizes of inner orifices and must match the vacuum diagram to reduce or hinder vacuum to other valves along the system. Unfortunately these can be hard to find and had us searching the local junkyards for similar parts.

A vacuum control valve (the blue part with multiple hoses) is threaded into the cooling system. It works by opening or closing as engine coolant temperature changes. Nowadays this is all done by a computer.

Atop the engine we sourced a freshly rebuilt carburetor from LMC Truck. Again we had to sift through the LMC catalog to find the correct year, transmission application, and California or federal emissions requirements.

In addition to the vacuum lines, the truck also has a charcoal canister plumbed into the fuel tank that captures gas fumes and recycles them. To verify that there are no leaks in the system, a pressure test is run on the fuel tank.

With a variety of new and used parts, the truck now runs clean and carefree, although it is noticeably down on power compared to its uncorked days. If you live in a less stringent state, consider yourself lucky, and keep an eye out for a small cabin with a huge shop on a couple acres near some four-wheeling trails, as we’re ready to move there.

How To Pass Emmissions Testing - 4-Wheel & Off-Road Magazine

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