Air Cleaner Restoration

We've been restoring a '69 Buick GS 400 convertible piece-by-piece while we continue to drive and enjoy the car. Whether you are doing a full frame-off or attacking your resto one piece at a time, you need to have a plan to be successful and to make the best use of your time. First, assess the condition of the part or parts assembly you are about to restore. Ask yourself the following questions: Is this piece salvageable? Do I have the resources to do the restoration? Would I be better off finding a replacement or even a reproduction? If you decide to restore the piece you have, then you need to organize the process: what parts you need to order, what materials you need to purchase, and what steps are required to get from start to the finish.

Ram-Air Explained
Here, we're going to restore the GS ram-air system/cleaner. This setup is typical of the fresh-air packages found on late-'60s-to-'70s musclecars. It draws in cooler outside air through two scoops in the hood when the throttle is mashed down and max power is called for. At lower throttle settings (higher manifold vacuum), the flapper valves in the air cleaner snorkles are closed and the engine pulls preheated air from a tube attached to the exhaust manifold. This heated underhood air improves fuel vaporization for better driveability. These sophisticated air cleaners enabled muscle cars to run well in all climates, something important for a mass-produced production vehicle. Our Buick GS ram-air system was pretty much intact, but looked like it had been through a rough 33 years.

Assessment
In assessing our ram-air system's condition, it was obvious that the foam air cleaner-to-hood seals and the decals would need replacement. The metal portions of the air cleaner assembly (lid and base) were dent-free, but the chrome lid was heavily rusted and pitted, and the base had bare metal spots with slight surface rust. The fiberglass ram-air portions of the air cleaner looked very worn. When new, they were a glossy charcoal-gray gel-coat with a slight texture. Our fiberglass had been worn down to a dull, light gray, with heavy gouges and scratches showing in some areas. After a little research, we learned that not all Buick GS 400s had chrome air-cleaner lids. In fact, most of them were semi-gloss black just like the base. That simplified the process for us. We decided to sand off the chrome plating and paint the lid black. At the same time, we would sand the base and give it a new coat of paint. Before we started any of this work, we ordered the new foam seals, decals and crankcase filter from a restoration supplier so that we would have these pieces when we needed them.

Fiberglass Fix
The fiberglass parts presented a dilemma. We could try to match the gel-coat color with touchup spray paint and just spray them to match as closely as possible. The problem is that it wouldn't look factory correct, so we experimented on a little section of fiberglass on the underside of the air cleaner. We used 220-grit sandpaper, then sprayed it with clear enamel—the results were amazing. The repair looked factory fresh. After cleaning the fiberglass parts in solvent, then washing them in hot, soapy water, the scratches were sanded smooth and a few coats of clear enamel were applied. The finishing touch was to clean the attaching screws on a wire wheel, paint them with clear enamel and then apply the reproduction Buick GS 400 decal. A tip on applying the adhesive-backed foil decal is to peel off the backing paper, then float it into place with a soapy water solution. Once you have the decal where you want it, just squeegee out the liquid and air bubbles.

Metal Work
The metal portion of the air cleaner took the most work because it was the usual multi-step process of sanding, priming and painting. The air-cleaner base just required light sanding with 220 sandpaper, priming with self-etching primer, finish sanding with 400-grit sandpaper, then several light coats of semi-gloss black enamel. The heavily pitted chrome lid was first blasted in the blast cabinet with aluminum oxide abrasive. It removed the chrome and rust at a slow rate but left a rough surface, especially around the rust pits. Then we hand-sanded the lid down to the copper plating and started building up the surface with many coats of primer and more sanding. With a little patience and lots of elbow grease, the pits finally disappeared. If we had it to do over again, we would probably look for an non-pitted lid instead.