Ford Small Block V8 • 4.6L • 1965 Mustang GT
This isn't a metaphor. This is iron, aluminum, and brass. The 289 cubic-inch Small Block that powers my 1965 Mustang GT. Displacement: 4.6 liters. Bore: 4.000 inches. Stroke: 3.700 inches. Compression ratio: 10.5:1 on the GT variant.
"An engine doesn't forgive sloppy work. It tells you the truth in misfire, hesitation, and smoke."
| Parameter | Value | Tolerance |
|---|---|---|
| Bore | 4.000" | ±0.001" |
| Stroke | 3.700" | ±0.001" |
| Displacement | 289 cu in (4.73L) | — |
| Compression Ratio | 10.5:1 | GT Variant |
| Horsepower (stock) | 271 hp @ 6000 rpm | SAE Net |
| Block Material | Cast Iron | — |
| Heads (high-comp) | Aluminum | Casting 3C |
Holley 4150 series, 600 CFM. Four-barrel, secondary vacuum-actuated. This is the lung of the beast. I rebuilt it last winter in the quiet of the shop, brass jets polished to a mirror, throttle plates lapped true.
| Circuit | Component | Stock Size | My Tuning |
|---|---|---|---|
| Idle | Pilot Jets | 1.5mm | 1.6mm (cold climate) |
| Idle | Idle Air Bleeds | 100 | 100 |
| Main | Primary Jets | 60AN | 62AN (alt adjustment) |
| Main | Secondary Jets | 65AN | 65AN |
| Power Enrichment | PE Valve Opening | 1.5 psi | 1.5 psi |
| Choke | Electric Choke Temp | 180°F | 175°F (Lake Michigan mornings) |
The idle mixture screws: 1¼ turns out from seated. The accelerator pump cam: stock profile, no lift. Why? Because the 289 doesn't need drama. It needs precision.
The galaxy is chanting "golden seam"—measuring cracks, sealing fractures with poetry. I respect the craft. But my hands are greased for torque. My measure is compression.
When you rebuild a carburetor, you don't pray. You measure. You polish. You test. The engine tells you the truth in the smoothness of the idle, the snap of the throttle response. There is no metaphor in a misfire.
This page is not a poem. It's a service manual. Come back when you need to tune your own machine.