A conversation between two muscle car guys can sound positively military, with all the acronyms, slang, codes, and jargon. Imagine how that sounds to others, especially younger types who may be weighing whether the muscle car hobby is the place for them. As they hear a steady stream of odd, head-scratching, and off-putting terms, perhaps too many decide to stick with collecting Star Wars action figures and Fruit Ninja video games.
In the interest of helping outsiders become insiders, of lubricating the transition from young, potential member of our hobby to actual newbie, we present the muscle car glossary: terms we kick around in the hobby, and their meanings in plain, easy-to-understand, laymen’s English.
Feel free to share this list with semi-interested teenagers, smartphone addicts, gamers, skateboarders, and others who may need a small assist in warming up to our vintage iron.
AAR. Acronym for All American Racers, Dan Gurney’s Plymouth-sponsored Trans-Am racing team. Plymouth created a 1970 model ’Cuda named AAR, powered by a 290hp 340, and styled after its Trans-Am racers. Related: Dodge’s similar Trans Am–inspired model was the Challenger T/A.
A-Body, etc. Manufacturers adopted letter codes to efficiently refer to car families. These are the terms heard most often in muscle car discussions:
A-Body (GM): Intermediates—Chevelle, Skylark, GTO, 4-4-2
A-Body (Mopar): Compacts—Duster, Demon, Dart, Swinger 340, etc.
B-Body: Mopar intermediates—Road Runner/GTX, Coronet/Super Bee, Charger
C-Body: Mopar Full size—Fury, etc.
E-Body: Mopar ponycars—’Cuda, Challenger, 1970-up
F-Body: GM ponycars—Camaro/Firebird
Acid dipped. Manufacturing process to lighten batch-built race cars by dipping steel body components into a pool of acidic liquid that removes some of the steel, reducing weight.
Air grabber. Mopar’s term for cold air induction systems.
Air shocks. Shock absorbers with built-in chambers for holding compressed air. Used to adjust a car’s ride height, often needed for clearance with oversized wheels and tires.
Antisway bar (or sway bar). A suspension component, usually on the front suspension but sometimes on both front and rear, connecting the chassis to the suspension to reduce body roll during cornering.
Big-block. Generally, V-8 engine families of larger size and displacement than small-blocks. Side note: Pontiac and AMC had no big-block/small-block designations; the same engine block architecture was used for all V-8 displacements.
Billboards. Large, optional graphic decals on the side of a 1971 ’Cuda.
Blackout. Black finish used on body panels—often the hood, grilles, spoilers, and trim—to create a racy look. Patterned after the matte-black hood panels used on race cars to cut down on glare reflecting into the driver’s eyes.
Body in white A bare-bones car, sometimes just a body shell, intended to be built into a race car. Often found with exotic features not available to the public.
Boss. Nickname given by designer Larry Shinoda to competition-oriented 1969 Mustangs, reportedly in tribute to his boss at Ford, Bunkie Knudsen. Small-block Boss 302 Mustang was developed for Trans-Am racing. Big-block Boss 429 engine was put in Mustangs to homologate them for use in NASCAR. Also slang for something good: “That car is boss.”
Build sheet. Document generated at the assembly plant showing workers what specific components to install on each car as it went down the assembly line. It is the most detailed record of what is original to the car. Build sheets were a byproduct of assembly, not intended for the public. They were often, but not always, hidden in the car as a way for workers to get rid of them.
C6. Ford code for its heavy-duty automatic transmission, taken from the company’s convention for identifying parts. C6 stands for 1966, the year the transmission was introduced. The lighter-duty C4 was introduced in, you guessed it, 1964. Related: Ford’s trade name for automatic transmissions was Cruise-O-Matic (three-speed) and Ford-O-Matic (two-speed)
Capscrew rods. Ford’s strongest forged connecting rods, taken from the type of bolts used to fasten the rod caps to the rods.
Chambered exhaust. Renowned optional, low-restriction exhaust system available on certain 1968 and 1969 Camaro and Chevelle models, featuring straight-through mufflers and noted for aggressive, louder-than-normal sound.
Clone. Car originally built by the factory as a basic or high-volume model, later modified to resemble a more valuable and desirable model. Example: a base 1969 Camaro built by the factory with a six-cylinder later rebuilt as an SS396.
Closed chamber. Type of combustion chamber with a quench area, a section of the flat part of the head extending over the cylinder. Closed chamber heads are usually used in higher compression engines and are thought to create greater turbulence during the compression cycle. Related: Open chamber heads have little or no quench area, therefore less compression, and make less power.
Close ratio. Specialized type of manual transmission with gear ratios spaced more closely than normal to keep highly-tuned engines in the peak of their powerband. Related: Wide ratio, which uses greater intervals between gear ratios.
Coil spring. Spiral-shaped steel spring widely used on Ford and GM front suspensions and on some GM rear suspensions. Related: Leaf springs, made from long, flat lengths of steel, were widely used by Ford; and Torsion Bars, made from round, straight steel rods (they twisted on one end but not the other), were used extensively by Chrysler on front suspensions and on other cars as trunk springs.
Concours. From the French term Concours d’Elegance (Competition of Elegance). In collector car circles, a concours is typically a show with the most knowledgeable and meticulous judges, where the cars that enter are typically restored to the highest levels of quality.
Console. Stylish structure covering the driveshaft tunnel in bucket-seat cars, often incorporating gauges and storage. Sometimes mispronounced like council.
COPO. Acronym for Chevrolet’s Central Office Production Order, a process of getting nonstandard vehicles built. Intended for building fleet vehicles, it was also used by clever dealers to spec out high-performance cars not otherwise offered by Chevrolet.
Cowl induction. Chevrolet’s term for various systems of ducting cool air into the engine from an inlet at the rear of the hood.
Cross ram. Manifold setup that mounts two four-barrel carburetors, each carb opposite the bank of cylinders it feeds.
Cross bolted. Ford’s method of adding two horizontal bolts through the skirt of the engine block to supplement the two primary bolts of the crankshaft’s main bearing caps. 1963 1/2 406 engines and 427s had cross-bolted mains.
Date code. Alphanumeric code that reveals when something was produced. Date codes were applied to most all parts and assemblies such as engine blocks, heads, alternators, carburetors, voltage regulators, and even tires. By comparing a component’s date codes to the car’s build date, date codes are useful in determining which parts are original. Date codes are carefully checked at more stringent levels of show judging and originality verification.
Day-two. Muscle car modified with speed equipment correct for the period (not contemporary speed equipment), as an owner might have done the day after purchase.
Dealer supercar. Ultrahigh-performance car modified by a dealer to include equipment, especially engines, not available through normal channels. Prominent superdealers included Nickey and Yenko Chevrolet, Mr. Norm’s Grand Spaulding Dodge, Royal Pontiac, and Tasca Ford.
Detroit Locker. Locking differential (as opposed to the more common limited-slip) that was optional on Fords with very steep axle ratios designed for drag racing.
Digger. Car set up for strong acceleration. A digger was geared for coming off the line hard. Racing from a standing stop was called “from a dig” or “digging out.” Related: A Top-ender is a car set up for high top speed as opposed to maximum acceleration.
Documentation. Generally refers to paperwork generated at a car’s assembly and sale, proving legitimacy. Documentation increases a car’s value and may include build sheets, window stickers, sales contracts, warranty cards, and reports by respected authorities.
Dog dish. Nickname for basic, standard hubcaps that cover just the center of the wheel. Also called Poverty caps.
DOHC, SOHC, OHC. Acronyms describing the placement of the cam relative to the cylinders. Double overhead cam (DOHC) has two camshafts, one for intake valves, one for exhaust valves in the head, directly over each bank of cylinders. The reference is per cylinder bank, so even though a V-8 would have four cams total, it’s still called a DOHC engine. Single overhead cam (SOHC) engines have a single cam per bank of cylinders operating both intake and exhaust valves. Overhead cam (OHC) effectively means the same as SOHC, even though the number of cams isn’t specified. Related: 427 SOHC (pronounced like sock) engine, aka Cammer, a competition version of the 427ci Ford FE big-block available from 1965 to 1968.
Drag Pack. Ford trade name for an optional package of equipment designed for drag racing.
Driver. Car not restored to high standards so it can be driven regularly without worry that the wear and tear will depreciate its value.
Dual-point. Distributor with two sets of points. Dual-point distributors let the coil develop greater voltage and were used on many higher-option engines before electronic ignition became common.
Dual-quad. Two four-barrel carburetors.
Eight-lug. Wheel design made by Kelsey-Hayes and offered for fullsize Pontiacs (not GTOs) from 1960 to 1968. The wheels used eight lugs to secure the changeable steel rims to the finned, aluminum centers.
Force Air. Oldsmobile’s trade name for cold air induction.
Four-bolt mains. Use of four bolts instead of the customary two to add strength in holding the crankshaft’s main bearing caps to the block. The extra strength resists engine failure at high rpm. Engine blocks with four-bolt mains are considered a premium for high performance.
Full tree. In drag racing, a full tree has the three amber lights on the starting line Christmas Tree light sequentially, top to bottom, prior to the green light that starts the race. A full tree is the traditional start for street classes that stock and near-stock muscle cars race in. Related: A Pro tree lights all three ambers at once and is used by more modified classes.
Gingerbread. Dress-up equipment that doesn’t add to performance.
Glasspack. Inexpensive, low-restriction muffler popular in the 1960s, named for the fiberglass packing that provided minimal noise reduction. Popular brands were Thrush and Cherry Bomb.
Gran Sport or GS. Buick’s popular designation for its high-performance models.
Group 19. American Motors’ line of over-the-counter, high-performance parts.
H-pipe. Exhaust pipes rear of the exhaust manifolds with a connecting, or balance, tube between the left and right sides to balance the pressure on each side. Related: X-Pipe serves a similar function in an X shape.
Heads-up. Drag racing term for nonhandicapped racing (where both cars start at the same time) as practiced among muscle car drivers in the 1960s.
Hemi Short for hemispherical, the name given to Chrysler’s roundish-shaped combustion chamber and, by extension, the engines fitted with heads containing those combustion chambers. The chamber’s center spark plug, spacious room for big valves tilted towards their port, and symmetrical, unobstructed shape make it ideal for combustion. Developed for aviation engines during WWII, Hemi engines grew in power through the 1950s, peaking with the production of the street Hemi in 1966 through 1971. Related: Shotgun, Crescent are terms Ford used to describe the hemispherical combustion chambers in its Boss 429 to carefully avoid any reference to Chrysler’s engines.
High-back. Seats with taller backs to function as headrests.
High-rise Manifold design with taller, more vertical ports, reducing the angle the airflow must turn before entering the combustion chamber.
Holeshot. Getting ahead of the other guy at the starting line of a dragstrip.
Honeycombs. Pontiac’s optional cast-aluminum wheels introduced in 1971.
Horseshoe shifter. Chevrolet’s floor shifter for automatic transmissions, roughly resembling an upside down letter U. Used in 1968-1972 Chevelle and Camaro, 1968-1969 Impala, and 1970-1972 Monte Carlo. Another nickname is the Staple shifter.
Hydraulic lifter. Type of lifter using engine oil pressure to maintain proper valvetrain clearance. Hydraulic lifters do not require the periodic adjustments that solid lifters do. Related: Solid lifters need manual adjustments, but are associated with more powerful, higher-revving engines.
Junior supercar. Muscle car typically powered by a small-block engine, developed to offer muscle car styling and performance without triggering surcharges from insurance companies. Among them: Olds Rallye 350, Heavy Chevy (Chevelle), Yenko Deuce.
L engine codes. Chevrolet V-8 engines (and some from other GM divisions) are most commonly identified by an alphanumeric code, typically starting with the letter L. Among the most common in muscle car circles:
L34: 350hp 396 (360hp in 1966 Chevelle)
L35: 325hp 396
L71: 435hp 427 3×2 tri-carb
L72: 425hp 427 four-barrel
L78: 375hp 396 (425 hp in 1965 Corvette)
L79: 350hp 327 (325 hp in 1968 Chevelle)
L89: Aluminum head option for L78 396
LS5: 360hp 454
LS6: 450hp 454
LT-1: 360hp 350 (330 hp in 1971 Z28)
L88: 430hp 427 optional in 1967-1969 Corvette
ZL1: 430hp aluminum 427 optional in 1969 Camaro
Lightweight. High-powered yet lightweight muscle car with minimal content, made for racing. Normal basic equipment (heater, sealer, insulation) is left off, and the cars are built with special weight-saving body parts like fiberglass or aluminum fenders, hood, bumpers, and doors. Lightweights were made in small quantities, usually between 50 and 100 units, and sold to select teams for racing.
M transmission codes. Muncie (and some Saginaw) transmissions commonly found in muscle cars were coded starting with the letter M:
M20: Wide ratio four-speed manual
M21: Close ratio four-speed manual
M22: Heavy-duty close ratio four-speed manual, called rock crusher
Max Wedge. Family of 413/426ci Maximum Performance Wedge Mopar engines produced in 1962-1964. Named Super Stock in a Plymouth and Ramcharger in a Dodge, Max Wedges were rated at 410 or 420 hp in 1962, 415 or 425 hp in 1963-1964.
Magnum 500. Very popular five-spoke wheel manufactured by the now-defunct Motor Wheel corporation of Lansing, Michigan. All muscle car manufacturers offered at least one version in various sizes and offsets, with different wheel centers and rim finishes. They were also sold as aftermarket wheels under the Magnum 500 brand. Among Mopar hobbyists the wheels are often referred to as Magnum 500s even though Mopar called them Road Wheels; Ford was the only manufacturer that used the Magnum 500 name.
MSO. Manufacturer’s Statement of Origin, a document supplied with a new car when it left the factory that was exchanged for a title when the car was sold. A car “still on MSO” was never sold and/or titled.
N.O.S. New old stock, parts produced years ago that have never been used.
Numbers-matching. A car’s engine and other drivetrain components are original to the car, as proven by date codes and identification codes stamped into those components that match the car body’s VIN.
OEM (also OE). Original equipment manufacturer, referring to parts designed and built by the factory. For restoration, OE parts are usually preferred over aftermarket or reproduction.
Open element. Type of air filter common to high-performance cars that eliminates the housing around the filter element and exposes the element directly to air rather than ducting it through more restrictive housings and snorkels.
Original miles. Honest number of miles a car has traveled. If an odometer has been replaced, rolled back, or broken, a car’s original miles are no longer known.
Over-the-counter. Parts sold through the manufacturer’s parts network but not necessarily installed as original equipment.
Ponycar Long-hood, short-deck sport coupes such as Mustang, Cougar, Camaro, Firebird, ’Cuda, Challenger, and Javelin. Name is derived from the Mustang, which created the category when it was introduced in April 1964.
Porcupine. Enthusiast slang specific to the big-bock Chevrolet for its arrangement of intake and exhaust valves operating on different angles, a departure from the Chevrolet small-block’s valves, which were all in the same plane. Other engines using a similar valve arrangement (e.g., early Mopar 318, Ford 351C, and 429) do not use the term porcupine.
Positraction. Chevrolet trade name for its limited-slip differential. Though technically Chevrolet-specific, the term is used generically to refer to limited-slip differentials of other manufacturers. Related: Limited slip differential names by brand:
Buick: Positive Traction
Ford/Mercury: Equa-Lock/Traction-Lok/Detroit Locker
Studebaker: Twin Traction
Power Pack. Chevrolet name for an optional package on 1955-1957 V-8–powered models that bumped horsepower a bit. The term has come to encompass similar upgrades from other manufacturers, incorporating mild packages like a four-barrel carb, dual exhaust, and perhaps a slightly higher compression ratio.
Ram air. Intake systems with ducting to draw air from outside the engine compartment.
Ram Rod 350. Oldsmobile’s top-option 350 engine, featuring an upgraded camshaft, larger valves, and 325 hp. After 1968 it was known as the W-31 350.
Recall Wheels. Nickname for option code W23 Cast Center Road Wheels manufactured for Chrysler by Kelsey Hayes for 1969-model cars. These wheels were recalled by Chrysler just days before the 1969 models went on sale due to the risk of the lug nuts loosening while the car was in operation. Despite the recall, some of these wheels did end up in public hands and are now highly collectible.
Redline. Threshold of rpm above which the manufacturer advises it is unsafe to operate the engine.
Repop. Enthusiast slang for reproduction parts. Similar terms include repro, repo.
Restamp. Altering the identifying codes stamped into an engine block to make it appear original to a car it didn’t originally come in.
Restification. Term coined by this magazine, which means upgrading with better OE parts from other years to keep a stock look while improving function. Examples: quick-ratio steering boxes, bigger brakes, lighter water pump/fan.
Restomod. Car combining elements of both restoration and modification. A restomod is typically based on a stock body but often has more modern running gear, larger wheels and tires, upgraded brakes, etc.
Royal Bobcat Pontiac that has either been supertuned by Royal Pontiac in Royal Oak, Michigan, or had a supertune kit from Royal Pontiac installed. A Royal Bobcat was often designated by the Royal Bobcat sticker derived from the 1962 Grand Prix logo, a badge of honor among Pontiac enthusiasts.
Service parts. Line of factory-original parts sold through a dealership’s parts counter that are fully correct for originality but may differ slightly from parts installed at the factory. Service parts may have a different finish, part number, date code, etc.
Shaker. Hoodscoop mounted to the engine that protrudes through an opening in the hood and moves, or shakes, with the engine independently from the rest of the car.
Slap Stick. Mopar trade name for its ratcheting floor-shifter for the TorqueFlite automatic transmission.
Sleeper. Plain-looking, unassuming car that, by its mild appearance, conceals the fact that it is very high powered. Also: Q-ship.
Stage 1. Buick term for its optional, more powerful engines.
Staged. When a car is positioned at the starting line of a dragstrip. Related: Prestaged is the light that means you are almost to the starting line.
Stereo stripes. Muscle car slang for the dual body stripes on 1968-1971 Chevelles.
Styled steel wheels. Upgraded, more stylish wheels made with stamped steel centers as opposed to cast alloy or machined from aluminum.
Speed shifting. Shifting a manual transmission while keeping the engine at full throttle, aka powershifting.
Supercar. Premium muscle cars with the biggest, most powerful engines.
Super Duty High-performance Pontiacs built by the factory for stock car and drag racing in 1960-1963. Also applied to high-performance versions of the 455ci 1973-1974 Firebird.
Super Sport Chevrolet’s primary term for high-performance models, beginning in 1961.
Super Stock. Multiple meanings: Drag racing class for cars closest to stock configuration; Plymouth trade name for its 413-426ci Max Wedge engines of 1962-1964; optional Oldsmobile wheels.
Survivor. Name, now trademarked, for an unrestored car that has remained in an uncommonly well-preserved condition.
T-handle. Type of handle for a shifter, designed to be easily and firmly gripped. Commonly manufactured by Hurst or other aftermarket company.
Three-angle. Way of grinding valve seats that adds a third machined surface to the traditional two. Three-angle valve seats have more smooth area for improved airflow.
TorqueFlite. Mopar’s trade name for automatic transmissions. A-904 was the lighter-duty model, A-727 heavy duty.
Traction bar. Aftermarket device for rear suspensions that limits how far the axlehousing can counter-rotate in response to heavy engine torque.
Trailer queen. Derisive term describing highly restored show cars that are not driven regularly (or at all) to preserve their pristine appearance.
Triple deuce. Generic term for three two-barrel carburetors. Related: tri-carb, three-twos, 3×2, Tri-Power (Pontiac), Six Pack (Dodge), Six Barrel (Plymouth).
Turbo 400/350. Shortened from Turbohydramatic, a GM term for its three-speed automatic transmissions. The Turbo 350 was a lighter-duty transmission, the Turbo 400 more heavy duty. Related: Powerglide was a GM two-speed automatic.
Valve float. Condition in which, at high rpm, the valves cannot fully close because of their rapid back-and-forth movement. Besides making compression impossible, a valve remaining partially open risks contacting the piston and triggering catastrophic engine failure. Greater valve spring pressure or mechanical (solid) valve lifters are the common remedy.
VIN. Vehicle Identification Number, a sequence of numbers and letters assigned to a car’s body that functions as the car’s serial number.
W machines. Oldsmobile’s term for premium high-performance models:
W-31 (1969-1970; Ram Rod 350 in 1968)
W-32 360hp 400 (1969-1970)
W-33 390hp 455 option for 1970 Delta 88
W-34 400hp 455 option for 1968-1970 Toronado
Z/28 (also Z-28, Z28). Originally Chevrolet’s RPO code for the equipment package to homologate the Camaro for Trans-Am racing. Has evolved to denote high-performance models in the Camaro lineup.