 AM/FM from Pontiac-'63 st...  AM/FM from Pontiac-'63 style! |
 How many SDs have you seen...  How many SDs have you seen paired with A/C? |
 The '63 features Cameo White...  The '63 features Cameo White basecoat/clearcoat paint, 8-Lug wheels, and radials-all of which were added by the previous owner. |
 The 421 engine features the...  The 421 engine features the correct heads and intake manifold for a '63 SD engine, and the exhaust manifolds are correct for '61-'62 SDs. |
 These carburetors may or may...  These carburetors may or may not be SD correct, as there are no stampings on them to verify. Jim Mattison said he had seen carbs that he knew were correct for a 421 SD, and they too had no stampings. For reference, the carb numbers are 3433S front, 3435S rear, for '63 421 SDs with the two-four barrel induction. "Collector Barry Martin told me the linkage may be from a Buick since parts of it are welded, and Pontiac didn't do that," Bruce says. |
 Big tailpipes and the guttural...  Big tailpipes and the guttural tone emitted by them are the only clues to the fact that this is more than a luxo-cruiser--it's a luxo cruiser stuffed with an SD-dressed 421 and a four-speed. |
 You can see the VIN stamp...  You can see the VIN stamp here on Bruce's engine block. Note how the numbers don't line up and you can distinctly see a "3" stamp under that of the first "2" in the "14022" stamping. Part of another number seems to be under the "0" stamping. When run through PHS, the number reveals a 421 H.O. Tri-Power engine. There is a "3" and a "5" on the block, which would normally be the engine block code, but they have been stamped above instead of the usual place below the motor unit number (203163). Are the "3" and "5" part of the engine code "135U" or "13-5," either of which would denote a 405-horse 421 SD engine? If so, a "1" is not clearly visible and neither is a "U" in the photo. Bruce says traces of a "1" can be seen somewhat far left of the "3" and "5." According to Pontiac paperwork, the block code should be "11T" for 421 H.O. Tri-Power, but there seems to be no sign of it here. |
While the four-bolt main bottom end was reportedly treated to typical machining and replacement parts, there are no details on whether or not the forged-steel SD crank or forged SD rods were added. The cam is a custom Crane solid roller with 286/294 degrees duration and 0.525/0.543 lift. (A factory solid lifter No. 10 SD stick features 308/320 degrees duration and 0.445/0.447 lift with 1.65 ratio rockers.) Head modifications are unknown as well for this particular engine, and while roller rockers are an obvious choice given the cam, the ratio eludes us. Though we can't comment on the mods for these heads, factory No. 9771980 units were SD exclusives that outflowed production offerings and were originally fitted with 2.02/1.76 valves-larger than the valves in regular production heads.
A compression ratio of 11:1 is stout for the street, but it's somewhat better than the factory SD ratio of 12:1. Mixing air and fuel is a pair of 500-cfm Carter AFBs, and beneath them is a factory '63 SD aluminum intake No. 97770859. Spark is provided by a Delco points-type distributor and a stock coil, via Packard wires and AC plugs. Factory '61-'62 SD No. 540297 right and No. 540298 left cast-iron exhaust manifolds usher burnt hydrocarbons through a 2.5-inch exhaust system featuring Flowmaster mufflers, when the cutouts are closed.
A '63 Borg Warner T-10 four-speed trans is delivered the engine torque via a stock replacement clutch. And a 3.42 Safe-T-Track unit at the far end of the driveshaft distributes the twist to a pair of smoking 225/75R14 Mastercraft A/S 4 radials.
The factory interior remains, and the suspension and braking system refurbishing were all handled by the previous owner who did the swap, thus leaving Bruce little to do but research the GP's interesting engine and drive those 8-Lug wheels off his Pontiac.
With SD induction, heads, and exhaust on the 421 engine representing the best Pontiac had to offer in the early '60s, mounted in a vehicle that was factory-designed to balance luxury and performance, Bruce's '63 GP seems to have it all. Add in a dozen or more comfort options like this one has and you'll be lucky to ever get a look at this machine standing still. "It's got the ride of a Caddy with the engine of a musclecar," Bruce says. I've done nothing to the Grand Prix but drive it since I bought it." It may not be 1 of 3, but Bruce knew what he was getting into when he bought it-the problem now will be getting him out of it!