Frequently Asked Questions

Short answer: A car is considered “numbers matching” if all the part numbers and casting codes are correct and pre-date the car by the usual 1–3 months. Use the year-specific drivetrain ID pages on FGF as your guide:

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Short answer: The “best” build depends on your goals (match all the components to them), but for a normal streetable 350 the short version is:

A good order of operations: set general goals, then tune what you have (cheap gains), then address gearing, tires, and transmission/converter, and then the engine. For the full discussion, read Jim Hand’s articles and search the Q&A archives at classicalpontiac.com.

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Short answer: Here’s what set a 1968 350 H.O. apart from a standard 350 (compiled with input from Paul Spotts, formerly of Performance Years):

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Short answer: The engine, transmission, and component codes for a 1968 Firebird 350 H.O. are below.

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Short answer: Despite what the Anchor catalog says, the 1969 350 does not use two different motor mounts — both sides use the same mount, and it’s the same one used on 400s (Anchor PN 2254).

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Short answer: That number near the distributor is the block casting number — the full number is 9786133, which denotes a 1967 400 cid block (it’s like a part number, not the sequential build/serial number, which is on the front passenger side). Source: Pontiac Muscle Car Performance 1955–1979 by Pete McCarthy.

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Short answer: Built properly, a Pontiac 400 will make 450+ hp with commonly available parts. The big-picture rules: use a competent machine shop (don’t scrimp on the block), match the cam to the heads, and clean everything obsessively. Component-by-component specifics are below. (This is a built street/strip engine; for a stock rebuild, see the milder rebuild FAQs.)

Done right (with the chassis, gears of 4.33–4.88, slicks, and a race-prepped TH350), this is an 11-second — potentially low-10-second — combination.

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Short answer: A 455 swap is simple — all Pontiac V8s since 1967 share the same external dimensions (except the 301). Move your timing cover, water pump, pulleys, accessory brackets, and exhaust manifolds onto the 455 and it bolts right in. (Car Craft, Feb. 2001, covers a 326→455 swap with good photos.)

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Short answer: The 670 heads are a late closed-chamber design with shrouded valves — but they’re a prized junkyard find. Per Pete McCarthy’s “Pontiac Racer’s & High Performance Handbook,” the 670 is unique:

Opened up (chambers enlarged like the 1968-and-later 400/428 heads) with good valve springs, they make an excellent high-compression head — dropping compression to roughly 9.5–9.75:1. As a stock head at a good price they’re worth buying; modified, they’re outstanding.

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Short answer: That small coffee-can-shaped canister mounted to the firewall under the driver’s-side fender is the A/C reserve vacuum tank.

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Short answer: No true Ram Air car ever got factory A/C — that means 1967–68 Ram Air I, 1968 Ram Air II, and 1969 Ram Air IV cars. But a 1969 400 H.O. (“Ram Air III”) could get A/C with any transmission.

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Short answer: Two ways: move the A/C compressor (more work but less frustration), or reach the #2 plug through the inner-fender seal (mud flap) — easiest with the front jacked up and the wheel removed.

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Short answer: The idle mixture screws are the only control for idle fuel mixture — the main jets meter everything above idle, and changing jets won’t affect the idle. Adjust the screws for the smoothest idle, then lean slightly.

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Short answer: There are two ways to adjust hydraulic lifters — a running method and the poly-lock method.

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Short answer: AV gas is not a good street choice. It won’t burn pistons by itself, but modern AV gas is mostly unleaded/low-lead and formulated for altitude, so it gives little of the old octane benefit — and you’d have to re-jet to suit it. Higher octane only makes more power if you raise compression/advance to take advantage of it; a properly tuned engine makes the most power on the lowest octane that won’t detonate.

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Short answer: Cold-start backfiring usually points to the choke (sticking or not closing fully, causing a lean condition) and/or timing.

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Short answer: The A.I.R. (Air Injection Reactor) system came only on California Firebirds and is fairly rare. You can remove it and run without it: take off the pump and all its plumbing, screw threaded plugs into the head holes (all 1967 Pontiac heads have these holes — non-A.I.R. cars just used plugs), and plug the inlet on the underside of the air cleaner.

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Short answer: The stock 1968 400 cam options were:

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Short answer: Converting a 1968 2-bbl to an Edelbrock Performer 4-bbl is straightforward; the fiddly parts are the throttle linkage/cable, the fuel line, and the vacuum connections.

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Short answer: Carburetor number 7037262 decodes as a 1967 (4th digit “7”), late-half-of-year (3rd digit “3”) unit for a California-emissions V-8 automatic (last digit even = automatic; odd would be manual). It doesn’t list as a Firebird carb — likely a GTO unit. It’s a rare carb worth trading, but not worth spending a lot to fix if it isn’t correct for your car.

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Short answer: The two screws at the front base are the idle mixture screws — out (counter-clockwise) = richer, in = leaner. They only affect idle, not cruise mixture.

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Short answer: Swapping a 1968 350 from 2-bbl to a Quadrajet 4-bbl isn’t difficult, but watch a few things: the intake casting, the throttle cable/bracket, and the air cleaner.

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Short answer: A Chevy engine isn’t a direct bolt-in — Chevy uses a different bellhousing pattern from the Buick-Olds-Pontiac (BOP) family. You’ll need an adapter to mate it to the Pontiac transmission (~$65 from Summit/Jegs/PAW — ask, it’s not always cataloged), Camaro motor mounts and frame brackets (the subframe holes already exist), Chevy accessory brackets, and you’ll reroute the fuel line to the passenger side.

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Short answer: The chrome louvered “pancake” air cleaner was stock on 1967 Firebird 400s without A.I.R. (it was also used on Corvettes). California 400s, which came with the A.I.R. emissions system, used a traditional closed-snorkel air cleaner with a chrome top instead. Either way the car also had chrome valve covers, breather, and master-cylinder cover.

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Short answer: For correct, durable engine paint, Bill Hirsch Automotive (hirschauto.com) specializes in restoration finishes — the correct engine paint in pints or aerosol, plus 1,800° exhaust paint for headers. (It’s one source; others exist.)

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Short answer: On 1968 Quadrajets the Julian date code can be near the model number on the body, on the base at the rear, or (on some early-1968 carbs) missing entirely — e.g., the RA I 7028277 is often found with no date code. Early-1968 carbs are the most likely to lack it or have it on the base.

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Short answer: Here’s how that set of engine/carb/manifold markings decodes:

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Short answer: Gap the plugs to match your ignition, not the head castings: a points distributor takes about .040″, while HEI takes about .055″.

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Short answer: Functional (cold-air) Ram Air induction came on the 1969 RA III; 1968–69 400 H.O. cars did not have it. Apart from that, the RA III and 400 H.O. are 100% identical — same carb settings, cam, heads, and exhaust manifolds.

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Short answer: Beyond the 4-bbl and hotter cam, the Sprint package added: a higher-compression cylinder head, a larger harmonic balancer, low-restriction dual exhaust with a split (dual-outlet) manifold, dual valve springs, a different distributor, different engine bearings, and a few other items. You can add any of these individually to suit your budget.

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Short answer: A dipstick that shoots out or clicks against the cam/crankshaft means the lower (inner) tube is bent or missing — replacing it requires pulling the oil pan (you may be able to remove the distributor and jack the engine, otherwise pull it).

Also confirm you don’t have an A/C-vs-non-A/C mismatch — A/C cars use a different dipstick and tube, so a short tube with a long stick (or vice versa) will read wrong. On level ground, 5 quarts should read about 1/2 quart low on the stick.

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Short answer: The Distributor Vacuum Advance Valve Assembly (#9773623) was used on all 1968/69 Pontiacs with manual transmission and on 1967 manual-trans A.I.R. engines. It mounts on the right-rear of the intake manifold, and its plastic end cover is black (green, #9794257, on RA II engines). Don’t confuse it with the distributor vacuum control that attaches to the distributor itself.

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Short answer: 1968 was the only year for a dual-diaphragm (advance/retard) distributor, which retarded timing under certain conditions for emissions. Owners complained of a slight backfire while coasting downhill or decelerating, and a service bulletin had dealers disconnect the retard side. Yours likely already has it disconnected — check for a separate vacuum nipple on the advance/retard unit and make sure that vacuum source is plugged.

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Short answer: The 1968 dual-port unit is actually a combined advance/retard device for early emissions (paired with the redesigned 1968 heads). It isn’t strictly necessary — owners complained of popping in the exhaust from the retard function, and dealers frequently just disconnected the retard side.

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Short answer: Yes — the 1967 Turbo 400 uses an electric kickdown (detent/passing-gear) switch, activated near full throttle. On a 1967 it’s a plunger switch mounted to the intake manifold near the left-rear of the carb (bracket held by the left-rear carb bolt), tripped by an extension bracket on the pedal linkage. Two wires: black, and black-with-green-stripe.

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Short answer: The cheapest electronic upgrade is a junkyard GM HEI distributor from a Pontiac V8 (~$10) — it bolts on. The catch: you must run a full 12V wire to the distributor, because the stock resistor wire only supplies ~6–8V. HEIs are nearly maintenance-free (no points or dwell), start easier, foul plugs less, and outperform points.

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Short answer: The black emissions decal goes on the passenger-side filler panel, positioned 4½” from the outside edge and 1½” up from the bottom edge.

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Short answer: For a 1969, the way to confirm a numbers-matching engine is that the VIN on the dash matches the partial VIN stamped on the front right-hand face of the block (the partial VIN was also stamped on manual transmission cases and hidden on the body shell). The Engine Unit Number is a separate sequencing number — found on the Protecto-Plate and Chassis Broadcast Copy — with no tie to the VIN, so without the original Protecto-Plate it can’t be verified.

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Short answer: The clue is the partial VIN stamp (20P105982): the leading 0 means a 1970 car, and the P means it was built at the Pontiac assembly plant (which was building full-size cars like Catalina/Bonneville that year). For 1970, “YD” indicates a 2-barrel 400, ~290 gross hp from a full-size Pontiac — so this engine isn’t a 1967 Firebird 400.

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Short answer: Original engine-compartment finishes:

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Short answer: The engine build-date code is on the top surface around the distributor hole — a letter plus three digits: the letter is the month (A = Jan, B = Feb, …), the next two digits are the day, and the last digit is the year. Example: B157 = Feb 15, 1967.

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Short answer: Most of the engine is Pontiac Blue — block, heads, balancer, water pump, timing cover, intake manifold, oil-filter bracket, and tin (except chrome). Black goes on the pulleys, power-steering pump, accessory brackets, motor mounts, heater-hose bracket, and coil-mount bracket.

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Short answer: Quick answers to common rebuild questions, then a sample mild street build.

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Short answer: The engine “serial” (Unit) number and the VIN are two different numbers and will never match. But starting in 1968, a partial VIN was also stamped on the block — on the front lower face near the timing cover/harmonic balancer — and that should match your car’s VIN. If it does, it’s the original engine for the car.

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Short answer: Prime it before the first start. Procedure:

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Short answer: A one-digit difference like 205848 vs. 205818 is almost certainly the same number — a weak or partial stamping, not a wrong engine. The Engine Unit Number and partial VIN were hand-stamped (shallower than the code stamp), and the gang-stamp tool could slip during the strike, leaving a “4” looking like a “1.” Given how close they are, it’s the original engine — nothing to lose sleep over.

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Short answer: When the fan and shroud are the right sizes but you have zero clearance at the bottom and too much at the top, the engine is sitting too low — almost always worn/collapsed motor mounts (the water pump isn’t the cause).

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Short answer: 1967 V8 cars had 8 different belt/pulley configurations (1968–69 V8s have only 4). For 1967 (each assumes an alternator):

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Short answer: The engine-compartment filler panels came on A/C cars and 400s — including Sprints with A/C (the 3.8-liter cars in 1967) and the base 1968–69 OHC-6 4.1-liter one-barrel cars with A/C.

Source: real GM sheet-metal panels (not fiberglass) have been available from Fabulous Firebirds in Missouri — ask for Charlie, 573-783-5702.

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Short answer: To check whether a 1968 400 radiator is original: it should be embossed “HARRISON” on the tanks and have a production usage-code tag (400 codes are UQ and UP). For reference, a “UP” tank measures: upper outlet 1.5625″, lower outlet 1.875″.

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Short answer: There’s a long-standing claim that 1967–68 Firebird 400 carbs had a small bent tab/link limiting how far the secondaries open — supposedly to keep the Firebird below the GTO’s rated horsepower under GM’s “10 lbs per hp” rule. Many magazines and books mention it, but it’s not fully settled.

Bottom line: the rated-horsepower difference between Firebird and GTO 400s is documented, but the exact carb component remains debated — research continues.

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Short answer: The correct 1968/69 Firebird throttle cables by application are below — watch out for NOS cables being sold as something they’re not.

The 9792222 (yellow tag) was apparently still available from GM for around $25.

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Short answer: The firewall holes are different sizes — the A/C opening is about 6″ wide × 11″ tall (narrow and tall), while the heater-only opening is about 14″ wide × 5″ tall (short and wide). So a non-A/C heater box won’t simply bolt onto a former A/C car.

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Short answer: Per Jim Mattison (PHS), the correct gloss level on the firewall area is 85% black.

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Short answer: The fuel-gauge “sock” (filter) is a simple slip fit — it slides over the end of the pickup tube and has a built-in ring at the open end. The old one’s retaining ring comes off easily, and installation is just slipping the new sock on.

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Short answer: Either buy reproduction 1967–69 fuel lines, or make your own. To make them: a mandrel tubing bender (~$60, Sears Automotive) plus steel fuel/brake line from a parts store (sold in 25′ rolls) lets you build a line that looks like the factory piece.

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Short answer: On a 1967, the fuel line runs along the inside of the right (passenger) subframe from the rear of the car, then crosses to the left side along the front-subframe crossmember. A line follows the crossmember under the engine, joins the “Camaro” line with a short rubber hose, and the usual hose runs to the fuel pump — held by the same clips as the right-front brake line.

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Short answer: The original 400 Firebird fuel sending unit is GM #6427857 (“Gauge, Fuel Tank Unit”) — for 1967–68 F/8 with A/C and 1967–68 F/8 “400,” per the 1969 parts book. The key difference from the replacement units sold today is the vapor-return tube.

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Short answer: 400 engines and all A/C birds used a two-line sending unit (3/8″ fuel + 1/4″ return). The only off-the-shelf replacement is the single-line (326/350) unit — but the dual-line is reproduced.

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Short answer: The original 1969 tank finish was silver (galvanized). The Eastwood Company sells a close-duplicate coating.

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Short answer: You can tell without dropping the tank. Look at the fuel lines at the front-right of the tank: two lines = the two-tube unit (one fuel, one vapor return); one line = the one-tube unit.

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Short answer: Correct finish is a natural galvanized-steel tank with bare-steel (or gloss black) straps — per the Camaro Restoration Guide (Firebird and Camaro share the tank and straps). Clear-coating is a fine way to keep it fresh.

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Short answer: The 1968 (350/auto) vented through a vented gas cap.

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Short answer: The small vent tube on the filler neck is not unique to 400s. It’s a roughly 6–8″ tube that loops in a “U” and connects to a fitting on the body just above the filler tube, and members report it on 350 2-bbl and OHC-6 cars too.

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Short answer: There’s a thin metal gasket (a sheet-metal plate with four holes) that goes between the Quadrajet base and the intake, covering a heat passage in front of where the carb sits. Missing it causes leaks and a miss. It’s about $5 at a speed shop, and it’s needed on both 1967 and 1968 Q-jet intakes.

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Short answer: The 1967 061 heads are an open-chamber head (~72cc chambers) with 2.11″ intake / 1.77″ exhaust valves — giving roughly 9.8–10.1:1 compression with stock pistons. The downside is press-in rocker studs (which can be converted relatively cheaply).

References: Pontiac Musclecar Performance 1955–1979 (McCarthy) and the H.O. Specialties book “Pontiac High Performance Engine Design and Blueprint Assembly.”

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Short answer: For a 350 2-bbl converted to 4-bbl that you want streetable with low-end torque and decent mileage, use a mild cam — the Pontiac 067 grind or a Summit 204/214, and go no bigger than the 204/214.

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Short answer: It’s a tough job — the heater core is in the air box behind the glove box. On a non-A/C car you can usually reach all the bolts without removing the passenger-side fender well, and the control cables are easy to remove and replace. While the box is out, clean it up and refresh it with semi-flat black. (A/C cars are considerably harder.)

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Short answer: That bracket (the one bolting to the passenger head to keep the heater hose off the exhaust manifold) is black, not engine color. The correct location appears to be the far outside hole under the freeze plug (lower-left corner of the head), with the tang in the hole directly below it.

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Short answer: On an A/C car the heater-hose connections are reached from under the car: loosen a couple of inner-fender (skirt) bolts and wedge a piece of 2×4 in to spread it so you can reach up to the connections. Slitting the old hose with a razor knife makes it come off much easier.

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Short answer: There’s no “small-cap” HEI for a Pontiac block. Whether one fits a Firebird is a bit of a crapshoot — some cars need the firewall clearanced and some don’t. The difference is usually the condition of the body bushings and subframe (worn-out mounting pads let things shift and cause the clearance problem), so check those before reaching for a hammer.

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Short answer: Installing an HEI won’t reduce knock except by coincidence — it’s the advance curve that matters (an HEI only helps if it happens to have less centrifugal advance or a stiffer vacuum-advance spring). If knock is your only complaint, fix the advance on your current distributor instead.

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Short answer: As a rule of thumb: around 215°F is when you start watching the gauge, 225° is shut-it-down territory, 235°+ is dangerous, and 250°+ is where things warp and crack.

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Short answer: Ram Air was a 400-only induction option (open hood scoops, an under-hood sealing pan, and an air cleaner with a rubber ring that seals to the pan), with internal engine differences. Verify it by the engine block code (2 letters under the right head):

Also check the partial VIN (right side of the block near the timing cover), the head numbers (on the center exhaust-port boss), and the date codes (block, heads, manifolds, firewall data plate). A 400 hood and engine added to a 6-cylinder or 350 car doesn’t make it a real 400/Ram Air. To know how the car actually left the factory, get the PHS documentation (~$35, phs-online.com).

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Short answer: A common kickdown switch is the B&M unit (Summit part #BMM-20297). It’s intended to use an existing TH350 bracket when you swap in a TH400 — if you have a TH400 and no bracket, you’ll fabricate a small mounting bracket and a piece to attach it to the throttle. The linkage is adjustable and forgiving of mounting differences.

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Short answer: One approach members use on a 1968 350: add lead substitute and run 92-octane gas to restore the octane the engine was originally designed for. (This started as a fix for acceleration and knocking problems that appeared when forced to switch to unleaded in the mid-1980s.)

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Short answer: On a fresh engine, low pressure with a couple of lifters that won’t pump up usually comes down to one of three things: lifters that weren’t primed, a cam bearing scratched during install, or a missing oil-gallery plug.

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Short answer: For a 1969 350/TH350, the lower radiator hose should be about 1.75″ ID on both ends (and fairly short, ~15–18″). The Ames hose with a 1.5″-to-1.75″ flare was the wrong part — too long and the wrong diameter. A correctly sized lower hose is commonly available at NAPA.

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Short answer: 1967 Firebird 400s used one of five Rochester Quadrajet carburetors:

* With or without A.I.R.

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Short answer: Answers to the common OHC-6 rebuild questions — with one recurring theme: INFORMATION. Keep the service manuals on hand.

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Short answer: There’s no “small-block” vs. “big-block” distinction for Pontiac motor mounts — unlike Chevy, all Pontiac V8s (1955–79) share the same basic block size (with minor variants like the short-deck 303 and low-deck 301), so there’s no separate small-/big-block mount.

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Short answer: Break a fresh engine in gently — the first miles largely determine its life, so no full-throttle blasts.

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Short answer: Use the lowest octane that doesn’t cause detonation (pinging) — not simply the lowest available. Run too low and you’ll eventually break something; run higher than needed and you only waste money and raise emissions (it won’t help performance). 92 octane or higher won’t hurt anything.

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Short answer: Going OHC-6 to V8: the stock Saginaw 3-speed (3.11:1 first) won’t survive any V8 — plan on a Muncie or Borg-Warner T-10 4-speed, with the full V8 clutch change-over (the OHC-6 uses a different, longer z-bar and a different bellhousing). And for a car turning low 13s, upgrade the drum brakes to disc — you’ll never regret it.

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Short answer: OHC means Overhead Cam — on the first-generation Firebird it refers to the inline six-cylinder engine.

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Short answer: A properly built OHC-6 won’t wipe out cams — the trouble is almost always the upper oiling system and incorrect valve setup, not the design. Get the 1967 service manual (it has the most OHC-6 info) plus your car’s year.

66 1-bbl  4.9     67 1-bbl  4.9     67 4-bbl  4.99
68 1-bbl  4.8     68 4-bbl  4.9
69 1-bbl  4.8     69 4-bbl  4.9

A/C note: 1967 Firebird Sprints could have factory A/C, but 1968–69 Sprints could not (likely compressor failures at high rpm plus low demand). You can convert a 1-bbl car to a Sprint and keep the A/C, but some parts are specific to the A/C Sprints.

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Short answer: The 1968 400 dipstick uses three tubes:

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Short answer: Use an AC PF-24 oil filter.

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Short answer: First rule out the gauge — air in a new mechanical gauge’s line can make it read low until the air compresses, so bleed the line. Once you’ve confirmed real pressure at idle, if lifters aren’t pumping, pre-oil them (loosen the rocker, fill the pushrod with a pump oil can, reassemble and adjust without torquing, start it, tighten 1/4 turn at a time until the clatter stops, then torque).

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Short answer: Per the 1968 owner’s manual (non-detergent oils are specifically not recommended), the SAE viscosities are:

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Short answer: Oil thrown out of the dipstick tube at high rpm is usually either excessive blow-by (worn or broken rings — run a compression test before tearing into it) or a blocked crankcase vent. First make sure there’s a clean, unblocked breather on a valve cover (or a working PCV) — a capped-off cover builds back-pressure that pushes oil out the dipstick.

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Short answer: The AC PF-23 was an early 1967 V8 filter, superseded by the PF-24 (which the parts catalogs list). For a factory-correct look, the filter was painted PMD metallic blue (which obscured the AC logo) — so the practical advice is to buy a current AC filter and paint it PMD metallic blue rather than run a 30-year-old NOS filter on a fresh engine.

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Short answer: Most overheating on an older Pontiac comes down to the basics — coolant, fan/clutch, shroud, a clean radiator, and correct timing — so sort those before spending on big radiators and exotic pumps. The best clue is when it overheats. Aim to keep the engine at or below ~195°F.

On timing as a cause: wrong timing alone will overheat an engine — see Timing Adjustment to Fix Overheating Problems. And note the first-gen Firebird radiator is notably small for the V8s it had to cool, so the whole system has to be in good shape.

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Short answer: Engine-compartment sheet metal is eggshell/semi-gloss black; the frame and suspension are a flatter black enamel; and the steering/suspension linkage is left natural (unpainted). Formulas below.

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Short answer: Yes — keep the PCV; a vented breather alone isn’t enough. The PCV uses intake vacuum to pull blow-by gases out of the crankcase, preventing positive pressure that blows oil past the seals and out the dipstick, and reducing oil breakdown, internal varnishing, and fumes/odor inside the car.

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Short answer: For brush-on Pontiac engine paint, try POR-15 (Restomotive Laboratories) engine paint or Bill Hirsch — both reputable. POR-15 has a higher gloss but goes on thick: it shows brush marks on flat surfaces (oil pan, valve covers, valley pan) though not on rough ones (block, heads).

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Short answer: Compression ratio drives the octane requirement. Per Pontiac engineer John Sawruk, the pre-1971 (~10:1) engines were qualified on 100 research octane — he suggested ~94 pump octane plus a can of booster. The 1968 engines that actually required premium were the H.O., Sprint, and Ram Air.

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Short answer: High idle with the idle screw backed all the way out usually points to the secondaries not fully closing (commonly overlooked) or the throttle linkage/cable/bracket holding the throttle slightly open.

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Short answer: The half of the bushing with the metal sleeve goes between the frame and the radiator support, sleeve pointing up. The plain rubber half sits on top of the support over the sleeve — install it with its large hole facing down.

Note: some reproduction bushings are slightly large for the radiator-support hole and need trimming/filing, and the bolt can be too short. GM bushings are correctly sized and come with correct-length bolts.

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Short answer: The 1967–68 open-scoop Ram Air was a fair-weather system — there was no rain protection, so you simply didn’t run it (open) in the rain. Complaints about this led Pontiac to design the 1969 driver-controlled system that closed the scoops off to under-hood air when needed, and the 1970+ Trans Am “shaker” with a backward-facing flapper.

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Short answer: A firsthand account from a member who raced a 1968 Ram Air convertible (with Pontiac engineering contacts) — on the 400’s special engineering and how the Ram Air engine behaved.

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Short answer: The Ram Air hood baffle physically fits all 1967–69 Firebird 400 hoods. The carb shroud works on all 1967–69 Firebird 400s and 1968–70 GTOs — there were two types, with and without the heat-riser provision (the “with” version is uncommon).

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Short answer: This is a reference list of the 1968 Firebird Ram Air specifications and part numbers, with member corrections noted below.

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Short answer: A member found the original 1968 Ram Air installation sheets in the glove box of a RA II ‘Bird — documenting the upper and lower pan installation (and confirming the Generation-1 Registry’s research on the dealer hood modifications). Both sheets are below.

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Short answer: There’s no factory “kit” — you assemble it from pieces: the upper hood baffle, lower carb shroud, hood seal, shroud seal, air-cleaner lid, and open scoops. Bought used or repro, figure around $1,500 all in.

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Short answer: Yes — all 1967–68 Firebirds and 1968 GTOs with Ram Air used the same carb shroud (air-cleaner housing) and lid. The hood baffle is the same for 1967/68 Firebirds but different on the 1968 GTO (though they look similar). (No Carter carbs were used on any 1967 400 Firebird.)

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Short answer: The Ram Air V was never installed in a production car — just over 200 were sold as crate engines (plus some pieced together). There were two versions: a low-deck 303 for Trans Am racing (the 5-liter limit) and a 400. Pontiac also experimented with 366 and 455 versions, but the RA V program targeted drag and Trans Am racing. The closest production engine was the 1973–74 455 SD.

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Short answer: Before swapping out a repairable OHC-6, try fixing it — the common running problems are a vacuum leak at the hard-to-reach carb stud (a steel base gasket cures it) and a gummed-up distributor vacuum advance. Swapping in a V8 means motor mounts, a trans cooler, a bigger radiator, engine-harness rewiring, and cooling baffles — a lot of work to replace a historic engine.

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Short answer: It’s easiest to pull the engine and transmission together — remove the trans crossmember, radiator, and distributor, and it’ll come out (the fan makes it tight but usually clears).

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Short answer: No special tool needed. Clean the area around the unit, then use a small brass drift to tap the lock-ring tabs (there are 3 or 4) evenly around to the unlock position. Lift the sending unit out carefully — the filter element is usually fragile with age — and check/clean the o-ring under the flange before reinstalling.

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Short answer: The greenish-blue is just aged Pontiac Blue metallic — the original paint shifts green after 30 years of heat cycles. To repaint, use the correct Plasticote “Pontiac Blue Metallic” (#227/#228, the same paint Performance Years and others sell); it looks like the factory brochures when fresh and naturally ages to that green hue. Use a high-temperature primer (e.g., Plasti-Kote, good to 500°F).

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Short answer: The 7028269 Rochester 4-bbl was used on all 1968 Tempest and Firebird 350, manual-trans, 4-bbl engines. It’s not rare — about 6,442 engines used it (3,784 “WK” Firebird 350 HO + 2,658 “WR” Tempest, manual), plus service-replacement carbs — so don’t get carried away bidding; ~$200 is plenty (a good rebuild can run $300+).

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Short answer: For highway cruising, keep it below about 3300–3500 RPM to limit engine wear and save fuel (a taller tire, a different rear-axle ratio, or an overdrive transmission all lower cruise RPM). A normal operating temperature is roughly 180–205°F — even 210° is fine climbing a grade or sitting in August traffic.

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Short answer: Instead of replacing parts by guess, diagnose it the moment it dies — check for spark and fuel while it’s dead. If it’s fuel: suspect vapor lock in the steel line, a weak fuel pump, or a tank that isn’t venting (a vacuum forms in the tank and starves the pump). If it’s ignition: look for a loose wire or an intermittent component in the ignition circuit.

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Short answer: A miss that’s worst when cold and clears as the engine warms is most often plug wires breaking down (they need more voltage when cold) — replace them with a good set of Delco wires.

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Short answer: A fan rubbing the bottom of the shroud (with extra gap on top) usually means the front subframe/radiator-support bushings have shifted the sheet metal — or the shroud isn’t seated. First confirm the clips holding the shroud to the radiator are fully seated and the shroud isn’t hung up on the lower radiator hose or the petcock.

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Short answer: Missing or surging at a steady cruise (but fine under acceleration) usually comes down to ignition advance, a lean cruise mixture, or the distributor.

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Short answer: A small-block Chevy goes into a 1968 fairly easily (the Firebird shares its chassis with the Camaro). You’ll need:

Worth considering: a good reman or used Pontiac 400/428/455 is often available reasonably — many feel the car is “too cool to wear a bowtie.”

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Short answer: The #8 plug on an A/C 1968 is just cramped (not necessarily an engine-mount problem). The best approach is to remove the right-front wheel and go in through the wheel well: break the plug loose with a wrench on a short plug socket, then back it out with a compact ratchet (a Snap-On 3/8″-drive in a 1/4″ body works well). Some do it from underneath instead.

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Short answer: Pull the inner cable out from the top, behind the instrument cluster (leave the casing in place) — and feed a new cable in the same way, from the cluster down to the transmission. Grease the cable for smooth gauge readings.

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Short answer: A jumpy, nervous speedo needle is usually a dry cable — pull the inner cable, lube it with a quality speedometer lube, and reinstall. (It also prevents the dry cable from breaking.)

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Short answer: This one is an open research question. It’s claimed (per Jim Mattison) that the 1968 Ram Air used a unique speedo cable, but no factory documentation has surfaced — the parts book only shows that automatics used a special cable. Also unresolved: which Firebirds used the two-piece speedo cable, and exactly what the optional speedo-gear adaptor (sales code 591) was for. If you have documentation, the site welcomes contributions.

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Short answer: “400 Sport Option” is a label seen in the parts and accessory catalogs. The “400” option included more than the engine — it added appearance and performance items: chrome grille moldings, the front-bumper Pontiac Crest emblem, “400” emblems on the hood and deck lid, redline tires, chrome engine trim, dual exhaust, the 4-barrel carb, and firmer shocks/springs.

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Short answer: The Sprint package was essentially the engine, so many builders create the car the way they want. The mechanical Sprint pieces: a higher-compression head, the 4-bbl Quadrajet, dual valve springs, the hotter cam, and the dual-outlet exhaust manifold feeding a Y-pipe. Outside, only the rocker-panel emblems differ (all OHC-6 birds wore the “4.1 Litre Overhead Cam” emblems).

Note: many enthusiasts view the Sprint as a balanced ride/handling/performance package, not just an engine option (it inspired Herb Adams’ “PFST” tuner Firebird). Done tastefully, a Sprint conversion adds value — save your original take-off parts.

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Short answer: The short air-cooled coil is correct for the 1968–69 OHC-6. (1966–67 Sprints used a conventional oil-filled coil — with the TI transistor ignition in 1966 and CD capacitive-discharge ignition in 1967.) There’s no off-the-shelf replacement that matches the original air-cooled coil.

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Short answer: A real 1968 Sprint has single exhaust but a dual-outlet exhaust manifold (a Y-pipe joins the two outlets into one header pipe), so single exhaust is correct. Confirm it by engine code ZD with a VIN matching the car — that’s the correct Sprint block. Most other Sprint parts could be added to a base 1-bbl car, so verify the block and get PHS documentation.

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Short answer: Yes, the Sprint (the OHC-6 4-barrel) is genuinely rare and worth more — only 7,459 Sprints (including Tempest) were built, with about 1,850 having the 2-speed automatic. It’s considered in the same cherished class as the Ram Air cars.

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Short answer: A 1968 Sprint (OHC-6) uses a single-core radiator — look for a metal tag reading “ZA” (the HD-cooling unit is “UF”). A 3-core from a 350 V8 fits the same location (the finger guard may not), and OHC-6s don’t use a fan shroud. Persistent overheating usually means a clogged or poor-condition radiator.

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Short answer: Turning the key to nothing — no click — while lights and charging work points to: a loose/maladjusted neutral-safety switch (try shifting firmly into Park and back), a dead spot on the starter (dirty commutator/brush — tap the starter housing with a hammer while someone keys it; if it then cranks, replace the starter), or a loose battery/starter cable (even one that feels tight).

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Short answer: If you have power but the starter won’t crank (a bad solenoid or starter), you can bypass the solenoid to get home: with the ignition in the run position, lay a screwdriver across the battery-cable post and the adjacent (driver’s-side) terminal on the solenoid — it’ll crank and start.

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Short answer: For 1967 Firebirds, only the 326 H.O. used the Carter carburetor — all other applications (including the 400) used the Rochester.

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Short answer: The thermostatic vacuum switch (TVS, GM #3016754) sits at the front of the intake in the coolant passage and is a safety device against overheating. Normally it feeds ported vacuum to the distributor advance; when coolant rises above ~230°F it switches the advance to full manifold vacuum, advancing timing about 20° at idle to help the engine cool, then returns to ported vacuum once cooled. It was used on all 1968 V8s and 1969 V8 automatics (plus some early-1969 Ram Air III manuals and the 1971 455 HO).

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From the 1968 Diagnostic Manual:

Fig 6D-9 — Components of the Controlled Combustion System
[pdfjs-viewer url=/files/FAQ/docs/6D-9.pdf viewer_height=800px fullscreen=true download=false print=true]
Fig 6D-10 — Distributor Vacuum Layout, V-8 2-Bbl.
[pdfjs-viewer url=/files/FAQ/docs/6D-10.pdf viewer_height=800px fullscreen=true download=false print=true]
Fig 6D-11 — Distributor Vacuum Layout, V-8 4-Bbl.
[pdfjs-viewer url=/files/FAQ/docs/6D-11.pdf viewer_height=800px fullscreen=true download=false print=true]
Fig 6D-12 — Vacuum Routing Chart
[pdfjs-viewer url=/files/FAQ/docs/6D-12.pdf viewer_height=800px fullscreen=true download=false print=true]
Fig 6D-13 — Vacuum Routing Chart
[pdfjs-viewer url=/files/FAQ/docs/6D-13.pdf viewer_height=800px fullscreen=true download=false print=true]
Fig 6D-14 — Vacuum Routing Chart
[pdfjs-viewer url=/files/FAQ/docs/6D-14.pdf viewer_height=800px fullscreen=true download=false print=true]

A list member’s compiled research comparing the available documents:

[pdfjs-viewer url=/files/FAQ/docs/TVS/68VacuumDialog.pdf viewer_height=800px fullscreen=true download=false print=true]

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Short answer: The TH350 kickdown cable snaps into a square hole on the carburetor side of the throttle bracket. You need the correct 4-bbl bracket with that square hole — a 2-bbl bracket leaves the cable about 3/4″ short, and the ~$80 reproduction brackets are for 1968 and don’t have the TH350 square hole. (If you find a 4-bbl cable-mount bracket with the TH350 hole, grab it.)

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Short answer: An “F2”-stamped bracket is for a 2-bbl. The correct 1969 Firebird 4-bbl throttle-cable bracket is 9797415, stamped “F4.” There’s no difference between automatic and manual.

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Short answer: With an Edelbrock Performer intake and 600 carb on a 1968, the stock bracket is too short. Edelbrock’s #8015 “Pontiac” bracket is really just instructions to drill/bend your original bracket — awkward, and it assumes you have the original (which runs ~$75 at Ames).

A cleaner solution: a Lokar 24″ braided throttle cable plus a Lokar throttle-cable bracket (sold separately) — stainless, with dual return springs; it installs easily and looks good. Available at Summit Racing.

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Short answer: The GM part number for the kickdown switch (1968 400/TH400, “M-40”) is #9785545 — the same part used on 1965–66 full-size and 1967–69 Firebird M-40 applications.

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Short answer: A pedal that only opens the throttle halfway usually means bent inner carb linkage (from a too-strong return spring, or someone stomping the pedal into the old horsepower-limiting throttle stop) — or, as the original poster discovered, a cracked accelerator-pedal mounting bracket. Check the pedal bracket and the carb’s inner linkage.

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Short answer: To rule out timing as an overheating cause: disconnect and plug the vacuum advance (its only purpose is gas mileage), then set the initial timing to 8–14° BTDC and see if it cools.

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Short answer: Two ways to set timing — by the numbers with a timing light, or by ear. Either way, start with the vacuum advance disconnected and plugged.

See also: Timing Adjustment to Fix Overheating Problems for how a manifold-vs-ported vacuum source affects timing (and cooling).

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Short answer: 1968-and-earlier engines use an 8-bolt water pump and matching timing cover; 1969-and-later use an 11-bolt pump (two versions) and an 11-bolt cover (#482893 or 9796345). All Pontiac V8 timing covers physically fit all Pontiac V8s.

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Short answer: Using all the bracketry from the 326, a 400 bolts right in — no extra brackets needed (the 326, 389, 400, 428, and 455 all interchange). The only possible hangup is a 1975-or-later block, where some engines don’t have all the motor-mount holes tapped (or present) — 1970+ blocks were cast with five holes per side for early or late chassis. New motor mounts are a good idea after 30+ years, and don’t mix your 1967 accessories/brackets with later parts (pulley-alignment problems).

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Short answer: For a 1968 with the dual vacuum-advance setup, there’s a thermostatic control switch on the passenger side of the intake with five ports:

See also the “Vacuum Hose Diagrams for 1968” FAQ for the actual diagrams.

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Short answer: The correct 1968 400 vacuum-routing diagrams are below. (A common overheating cause is the distributor vacuum advance hooked to manifold vacuum instead of ported — and previous owners often cap off ports that should be connected.)

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Short answer: On a stock Pontiac, valve adjustment is easy — just tighten the rocker lock nuts to 20 ft-lbs and you’re done. (This even worked fine with an aftermarket cam for one member over 10 years of driving.)

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Short answer: The only reliable 350 H.O. identifiers are on the engine:

Both used casting #18 heads. Other clues aren’t conclusive — the 2-bbl 350 could have optional dual exhaust, both shared the same hood emblems/holes, and stripes could have been delete-optioned. To be certain, get PHS documentation.

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Short answer: The number on the body tag and the VIN won’t match — that’s normal. The VIN is the sequential production number; the body-tag number is the Unit (consecutive build) number. They’re separate systems.

Sources: Firebird Red Book; Catalog of Firebird ID Numbers 1967–93; Pontiac Historic Services; Year One catalog.

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Short answer: The 1967 voltage regulator mounts to three ~1/2″ holes high on the radiator support — the one with the rubber grommet, plus two others nearby (one is tucked under the front lip when viewed from the front). The rubber grommets (“well nuts”) have a built-in threaded insert that the screws thread into and compress (like a pop rivet); replacements are available at parts stores.

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Short answer: Yes — 1969 had two water pumps, an early (short) and a late (long) hub:

A/C-equipped cars used the longer pump. You can also tell which you have by the water-pump pulley.

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