Frequently Asked Questions
Find answers to Frequently Asked Questions for First Generation Firebirds that have been asked and answered on FGF. Special thanks needs to be given to all the FGF members who took the time to respond to other member's questions.
Engine - H.O. Specific
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):
- Transmission: TH400 (standard 350 autos used the TH350).
- Carburetor: 7029268.
- Heads: different from the standard 350 (#48 heads) — though some 400s reportedly got the 350 #48 heads for more compression, given low 350 H.O. demand.
- Exhaust manifolds: standard manifolds (the long-branch were apparently planned but not used; long-branch would need the oil-filter adapter to clear).
- Valve reliefs: present (the big valves, 2.11 + 1.77, exceed the 3.875″ bore) — possibly on all 350 blocks so the factory didn’t stock two.
- Cam: 067 (auto) / 068 (manual) per the AMA spec (not the 744, despite some claims).
- Power-steering loop: used on cars with high numeric gears (~3.73+).
Note: air shocks weren’t a factory item even in the HD suspension, and the passenger-side “hood scoop” seen in some literature (cold-air induction) appears to have been planned but not produced.
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Content last modified: June 13, 2026 at 10:06 am
Short answer: The engine, transmission, and component codes for a 1968 Firebird 350 H.O. are below.
| Engine | Code | Output |
|---|---|---|
| 350 H.O. Manual | WK | 320 hp, 10.5:1 |
| 350 H.O. Automatic | YM | 320 hp, 10.5:1 |
| Transmission | Maker | Code |
|---|---|---|
| 3-speed standard (column shift) | Saginaw | RJ |
| 3-speed standard (floor shift) | Dearborn | DB |
| 4-speed optional | Muncie | FX |
| 2-speed automatic | ST-300 | MB |
| 2-speed automatic (w/ A/C) | ST-300 | MC |
Other components: Cylinder heads “18” · Carburetor: MT 7028269 / AT 7028266 · Intake manifold (same as all 4-bbl): 9790140 · Exhaust manifolds (same as Std. & 400): 9794320 RH / 9777755 LH · Distributor: MT 1111447 / AT 1111282.
For reference, 2,087 400 H.O. Firebirds were made in 1968; the 350 H.O. count is likely similar or a bit lower.
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
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.
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
Short answer: The only reliable 350 H.O. identifiers are on the engine:
| Manual (WK) | Automatic (YM) | |
|---|---|---|
| Cam | 067 | 066 |
| Carb | 7028269 | 7028266 |
| Distributor | 1111447 | 1111282 |
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.
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
Content last modified: June 9, 2026 at 7:10 am
