Welcome back to the third installment of our multi-part series that focuses on the teardown and rebuild of an ultra-rare and desirable 1973 Super Duty. This 455-powered Pontiac Trans Am is being restored by the folks at renowned muscle car specialist Legendary Motorcar. Last time out, we followed the disassembly process and now we’re ready for the restoration to actually get underway.
With everything in pieces and the T/A literally reduced to the shell, it’s time for the real work to begin. One of the first processes was to have the unibody and selected parts sent out for blasting, in order to remove every last trace of paint and undercoating.
By taking the car back to bare metal, not only will it help provide a proper foundation when the time comes to apply epoxy primer and then begin the process of bodywork and paint preparation, but it will also reveal any potential problems, including rust or accident damage, which otherwise would have been hidden from view. Given that this car is approaching 40 years old, there’s a good chance that all is not what it initially seems, no matter how much documentation might come with it. It’s something that Legendary’s Chris Simon, who has overseen many restoration projects, is only too aware of.
“You can have paperwork, you can have pedigree, but until you start stripping the car down and taking it back to bare metal, you just don’t know what you might find. There are cars that appear to be clean, but once they’ve been stripped and blasted signs of extensive crash repairs can be discovered, or patch panels to hide rust are found. Most muscle cars have gone through a period in their lives when they were driven very hard and put away wet, so if you’re restoring one, it’s something you need to bear in mind.”
For our Super Duty project, the Trans Am’s unibody, doors, fenders, hood, and rear decklid–plus the front subframe and radiator core support–were all sent out for blasting. They went to nearby Fishburn-Proctor, a specialist that has performed the task on a number of Legendary restoration projects. F-P Vice President John Proctor was gracious enough to let us observe a good deal of the blasting process.
“When you’re taking a vehicle back to bare metal like this, there are traditionally two methods–chemical stripping or sandblasting. Both have pros and cons. With stripping you don’t have to worry so much about denting or warping the surface you’re trying to strip, but the downside is that chemical stripping is messy and can be quite hazardous. Secondly, there’s a good chance you won’t get all the paint or undercoating removed.
With blasting, there’s much less cleanup, but you’re using an abrasive compound, so there are a number of things you need to consider, not only providing protection for yourself–clothing, mask, breathing filter, but also the technique and type of media being used. It can be easy to cause damage to sheetmetal parts when blasting a car, so it’s something you need to consider before you begin.”
For doing large objects like a vehicle’s body or frame, Fishburn Proctor has a 16-foot-high by 18-foot-wide enclosed production bay. The Trans Am’s unibody was placed inside the bay on an adjustable dolly that can be raised or lowered for blasting different areas. For removing the paint and undercoating on our subject vehicle, John performed a soda blasting technique. Using formulated granules of sodium bicarbonate, a soda blaster is essentially a compressor attached to a hose and nozzle that, via pressurized air, forces the granules though the pipe and nozzle to blast the surface. Sodium bicarbonate is often used for stripping automotive parts, including bodies and frames on classic and vintage vehicles, because it is deemed as being highly friable–i.e., the sodium bicarbonate granules literally explode the material they come in contact with (in this case, paint and undercoating), causing it to disintegrate without damaging or distorting the surface beneath.
Using hard abrasives like silica sand (still widely used in many types of sandblasting) will strip the surface, but on sheetmetal parts it can also leave behind pockmarks or dents, which will mean additional time needed to prep the bodywork before paint.
The blasting process started with the underside of the unibody, removing the thick heavy coating on the floors, firewall, transmission tunnel, and trunk well. Once the surface was stripped, a few surprises began to manifest themselves. The floors actually had perforations in them; while it was revealed that both the left and right rear quarter panels had been repaired with poorly fitting patch panels welded over rusty sheetmetal. In addition, there were signs that sometime in the past a vinyl roof had been installed on the car–there were hole marks and signs of corrosion around the rear window. As for our small little bubble of rust we noticed on the passenger side A-pillar in part I, once it had been soda blasted, it revealed a quite sizeable hole.
As the body was getting blasted, so too was the car’s front subframe assembly and radiator core support; though once cleaned, there were no signs of repairs or serious rust issues here, just slight pitting. Once the body and these parts had been blasted clean, along with the doors, rear decklid, front fenders, and hood, they were shipped back to Legendary, ready to be dipped in epoxy primer.
While the body and frame components were being treated, the rest of the Trans Am’s components, including the glass, interior, transmission, suspension, rear end, fuel tank, brake components, and wheels and tires had been carefully labeled and put aside. The SD 455 engine, meanwhile, was sent out to Active Engines in nearby Mississauga for a complete teardown, inspection, cleaning, and rebuild. Although there’s still much work to be done on our Trans Am, with the metal work completed and body prep well under way, plus the engine in the hands of a capable machine shop, the project is really starting to gather some steam. Here we highlight some of the tasks accomplished so far.
Here’s the unibody of the Trans Am, completely stripped and on the dolly in the blast room at Fishburn Proctor. It will take several attempts to remove the thickly applied enamel paint and heavy undercoating.
Until the shell is actually taken back to bare metal, it can be difficult to see the extent of any rust or accident damage. On any old car like this, owners and restorers should at least expect a few sins to be hiding from view.
Along with the unibody, the car’s front subframe (shown) and radiator core support will also be blasted and cleaned.
Here’s F-P’s John Proctor, all kitted up and ready for blasting. He’s using a soda blaster, which will force granules of sodium bicarbonate through this hose and nozzle at high pressure. Unlike some other blasting tools, this particular setup isn’t gravity fed, relying on high pressure alone fed from an external source (in this case a compressor). Adequate protection is absolutely essential. If the sodium bicarbonate can strip heavy layers of paint in a matter of minutes just think what it can do to your skin and eyes.
During the blasting process we were able to observe the shell being stripped of its layers, albeit at a distance, using our 300mm zoom lens. The noise of the soda particles hitting the sheetmetal is simply deafening without ear protection.
Here’s our front subframe and radiator support after blasting has been completed. As you can see, they’ve been completely cleaned of any paint or residue and show no signs of damage. That’s a good thing, which indicates this car hasn’t been in an accident–well, at least a front-end collision.
Moving to the body, we have a good view of the floorpan after blasting. Note the numerous tiny rust holes on the driver’s side floor behind the crossmember, something that wasn’t visible before.
Once the body had been blasted, along with doors, hood, fenders, and trunklid, it was crated up and shipped back to Legendary Motorcar. Each of the body panels was then coated in epoxy primer, ready for metalwork and body prep. For the most effective results, the bare surface has to be properly treated before the primer is applied. Here, one of the Trans Am’s doors bakes in the paint booth after having received a coat of the epoxy primer.
And here’s a fender. The epoxy in the primer is designed to be porous, allowing the strands of the body filler to anchor to it. As the filler hardens or cures, the epoxy below it hardens at a faster rate, closing up the holes that bond the two substances together. This helps seal off the metal surface from moisture contained within the filler to prevent rust, as well as creating a strong bond between the primer and filler.
Finally, after the smaller parts have been treated, the unibody is coated in epoxy primer and left to cure, before being rolled out into the shop, ready for metalwork.
Looking at our Trans Am’s hood, you can see the nice, smooth finish resulting from the blast work and epoxy primer. This will make it much easier for applying both filler and paint.
A close up of the unibody revealed some quite nasty surprises. Both rear quarter panels were patched sometime in the past, and poorly at that. For a restoration of this caliber this is unacceptable, and this quarter will have to be cut out and replaced with a brand new one.
The passenger side was even worse. Take a look at the patchwork below the belt line crease and the craters and dents in the quarter panel–no wonder the contours didn’t look right when we first inspected this car in part I; the panel was caked in filler to cover up this mess.
Another area of damage was around the rear valance and the end of the quarter on the driver’s side. The good news: most of the damage was on the quarter panel, which is already slated for replacement–only a small part of the valance needed attention. For years, damaged and rusty valances were a bane for those wanting to restore 1970-73 Firebirds. Now, reproduction panels are finally available.
Another interesting set of marks on the car’s sheetmetal were these, just below the rear window. Because they were uniform on both sides, it led the team at Legendary to believe that a certain time somebody had chosen to install a vinyl top on this Firebird. “It was a popular styling trend back then,” says Simon. “A lot of cars that should not have had vinyl tops received them and in many cases, they were just moisture traps.”
Moving back to the right rear quarter, this small patch repair was likely done because of rust. On second generation F-bodies, rusted out quarters and trunk floors were very common, even on cars that weren’t driven through the bad winters.
More evidence of rust patching was found on the floors, especially on the passenger side close to the rocker panel. Looking at the damage, it was likely caused by water dripping in through the window and seeping into the carpet. This hole has been patched before but the rust wasn’t removed, so left unchecked it would simply spread.
With the heavy doors re-attached, metal work begins on the unibody. Note how the damaged rear quarter panel has already been cut out, and filing has begun on the A-pillars and door to remove any burrs or imperfections.
With the T/A’s body awaiting new rear quarters, note the cut line. Full quarter panels to the roof are not available for these cars, but companies like Classic Industries and Year One supply reproduction quarter panel skins (both left and right side), which reach up to this cut line.
Here’s one of the old quarter panels (the left one), ready for disposal. Note the extensive surface rust on the lower portion of the panel and around the wheel lip on the inside.
Another prime rust spot was the A-pillar on the passenger side. Rust has been cut out and new steel welded in and filed down for a smooth, uniform contour.
During our first installment, we noticed a few signs of rust at the rear of the passenger side rocker panel. Rather than taking any chances, a section of sheetmetal was removed. Once this entire area has been grounded and filed, a new patch panel will be fitted and TIG welded. The trick in preventing corrosion is to cut out and file away any evidence of it; otherwise, rust will eventually return.
Here’s one of the replacement quarter panels ready to go on the Trans Am. Note how clean and straight it is compared with the botched originals.
The original front fenders were in considerably better condition than the rear quarters, but still needed fettling. Here the lip where the fender meets the nose is formed into shape using a Dremel tool, for the best possible alignment (it wasn’t that great from the factory to begin with).
Having been checked, fettled, and filed, both front fenders are now ready to be attached to the unibody, in preparation for the primer and paint prep to begin. In order to achieve the best possible results when painting the car, it’s advisable to prep all the body panels together as a unit. Otherwise you’ll get major inconsistencies, not only when applying filler and sanding, but also when applying individual coats of paint, resulting in variations of pigmentation, finish, and color.
Our Trans Am’s shell, with the new quarters and rear decklid attached, is wheeled into the body shop and the sanding and filler process begins. To start out, a fairly coarse paper, such as 180 or 220, is needed in order to provide a good adhesive surface for the filler to stick to the primer.
As they say, everything is in the preparation when it comes to doing bodywork. Using 3M 180-grit paper, Legendary body man David Munro works across the decklid. The key to achieving a successful result is using paper that scuffs the surface enough to provide a good contact point for the filler without removing too much of the primer, which could cause moisture from the filler to come in contact with the bare steel beneath.
Even after several hours of sanding, there are still some low spot areas on the decklid that need attention. You’ll want the filler to stick as best as possible over a nice, smooth, uniform surface, so as many imperfections as possible need to be removed.
Here is a complete view of the body with the doors, hood, and fenders attached, in the sanding and prep area of the shop. Note how David is starting at the back of the car and working his way forward.
Another part of the sanding process is marking off the crease lines on the body–in this case along the rocker panels, the belt line, and the tops of the fenders where they meet the sides, along the tops of the doors and the car’s rear shoulders. This is important to maintain definition of the original form line when sanding and also when applying body filler.
After taping along the bodylines on the left side of the car, it’s time to tackle the right.
In order to provide a clean, unbroken definition of the original bodyline, the tape needs to be stretched and applied in an unbroken line–in this case, from the beginning of the front fender to the end of the rear quarter panel.
Now it’s time to apply the filler. You’ll need to mix the filler with a hardener in order to allow it to set once it’s been applied. Although there is no hard and fast rule when it comes to mixing the two parts together, you’ll want to blend them until the paste is a uniform color (if in doubt, talk with a body shop professional or consult the company whose product you’re using for the required consistency).
Essentially, you’ll want to mix the two materials as few times as possible to help avoid different consistencies in both filler and hardener content.
Having consistently mixed the filler/hardener, Munro applies it to the door of the Trans Am. When doing this, you need to maintain a balance between not enough and too much filler, especially over large sections like this door skin.
During the early stages of adding filler, there will likely be numerous imperfections and low spots, so it’s best to add more filler rather than starting out with too much, as it will only mean more sanding. Note how David is using the tape as a guide for filling and sanding specific areas of the door to maintain the original contours.
Once the filler has been applied, it has to cure. It will usually harden within 20 minutes, though add or subtract time for colder or warmer than average temperatures respectively. When it has dried, the filler will have the texture of a non-stick surface, like the bottom of a frying pan. Once it has dried you can also remove the tape.
Now that the filler has cured, David sands over it using 180-grit paper. For any low spots on the surface (usually revealed by darker shades), more filler will need to be added until the spots are removed and the finish is nice and uniform.
During sanding, the paper will eventually wear away; that’s why it’s important to have a ready supply when tackling a project such as this.
While the body was being prepped for paint, the 455 V-8 was sent out to Active Engines and completely dismantled ready for rebuilding.
The original block (seen here) has been hot tanked (submerged in a hot, caustic solution to strip it of any paint, oil deposits, or other sludge that’s been allowed to build up over the course of some 37 years).
Once it has been tanked, the block is then scrubbed using surface conditioning discs to remove any remaining foreign material. On iron blocks like our Super Duty 455, medium grade discs are generally used. The block is then de-burred to improve oil circulation and to reduce the risk of cracks forming on the surface. In this picture, with the de-burring process completed, new main bearing studs have been added. Note the four-bolt main bearing cap (one shown installed for illustration at this point) a hallmark of the Super Duty 455.
In factory configuration, the stock nodular iron crankshaft was actually a weak link in the SD package. It was almost identical to the cranks found in regular 455 Pontiac engines, save for the addition of deep rolled fillets in the journal area to increase bearing contact, in order withstand higher rpm use, not something classic Pontiac V-8s were traditionally known for. In this particular engine, the owner has chosen to replace the stock crank with a stronger forged steel 4340 crank courtesy of Eagle Specialty Products. Along with .060-over pistons, it will help transform this veteran V-8 into a 467-cubic inch powerhouse.
Because the block will be punched out .060-inches over its stock 4.15-inch bore, new oversized pistons will need to be specified. This Keith Black Hypereutectic piston, listed as part No. 347, is a solid dome design with a centered pin and conceived for use in engines where the head angle is set at 14 degrees, which makes it suited for Pontiac V-8s like our SD 455. It also features a rigid skirt design for greater strength, and a unique ring configuration with greater clearance in the top ring.
The SD 455 was originally fitted with pressed-in valve guide sleeves to promote steady, even flow through the ports from one end to the other. The original pieces were made from cast-iron and designed to be removable. Some time in the past, when this engine was “rebuilt,” the original guide sleeves were removed and replaced by shortened cast iron units that were of an oddball length. They will be replaced by longer, new bronze sleeves, custom made for this particular engine.
The new, longer sleeves will help improve cylinder head flow. SD 455 heads were among the most efficient of their day and it’s said that even a bone stock SD 455 head can flow more than 230 cfm at just 0.550 inches of valve lift.
Derived from those found on the 455 H.O., the Super Duty heads featured modified round ports, with a constant cross-section area, which resulted in ports that were both wider, taller, and more efficient, allowing the SD heads to flow approximately 10 cfm more of air at the same lift as the 455 H.O. pieces without any change in actual valve diameter, which was 2.11 inches (intake), 1.77 inches (exhaust).
In this view, you can see the round port design to full effect. As much material as possible was removed from the head to maximize flow through the ports. As a result, the pushrod passage actually penetrated into the sidewall of the exhaust port. The things those Pontiac engineers did to make power, even in the smog era!
Part of any engine build like this should include all new bearings for maximum performance and durability.
Other components we’ll be using on our SD 455 are all-new valvetrain pieces: springs, lifters, and retainers, plus a brand new timing chain set and camshaft, courtesy of Comp Cams. We’ll delve deeper into valvetrain specifics during the next installment of this project.
Considering the abuse most muscle cars have been subjected to, the original valves on this Super Duty 455 were in surprisingly good shape, none were noticeably bent or damaged. Carbon deposits were also minimal.
All lined up and sitting pretty on the workbench, the SD 455 round port heads and valves await attention.
Along with new reciprocating parts and bearings, new gaskets are also essential for proper oil, coolant, and exhaust flow and sealing. In this picture, you can see new Fel-Pro cylinder head, intake manifold, and exhaust manifold pieces we’ll be using to provide more than adequate sealing for this monster V-8.
939 Winston Churchill Blvd.
Ontario L5J 4P2
3406 Democrat Road
Memphis, TN 38118
Federal Mogul (Fel-Pro Gaskets)
26555 Northwestern Highway
Southfield, MI 48033
Fishburn Proctor Ltd
15479 Steeles Ave East
Ontario L0P 1E0
Legendary Motor Car Company Ltd
8228 Fifth Line
Ontario L7G 4S6