All Models (1974)
- Connect CO meter to exhaust system tailpipe. Set curb idle speed to specified idle RPM with idle stop solenoid energized and extended.
- Record idle CO reading. If CO level is within limits and engine idles smoothly, no further adjustment is needed. If CO level exceeds value shown in specifications, proceed with adjustment.
- Turn each idle mixture cap clockwise in equal amounts until idle CO is at or below percent shown in specifications. Do not remove limiter caps. Reset curb idle speed (if necessary) with air cleaner in place and idle stop solenoid energized and extended.
- Reconnect fuel tank vent hose and distributor vacuum advance hose. Install fuel tank filler cap on Corvette models.
Idle Speed and CO Specifications
| Application | Curb Idle RPM | Lean Drop Idle Speed RPM | CO Level | |
|---|---|---|---|---|
| 140" 1-Bbl. & 2-Bbl., All | ||||
| Auto. Trans. | 750 | 800/750 | .3% | |
| Man. Trans. | 700 | 800/700 | 3% | |
| 250" Federal | ||||
| Auto. Trans. | 600 | 650/600 | 3% | |
| Man. Trans. | 850 | 950/850 | 3% | |
| 250" Calif. | ||||
| Auto. Trans. | 600 | 630/600 | .15% | |
| Man. Trans. | 850 | 950/850 | .5% | |
| 350" & 400" 2-Bbl., All | ||||
| Auto. Trans. | 600 | 650/600 | .5% | |
| Man. Trans. | 900 | 1000/900 | 5% | |
| 350" & 400" 4-Bbl., Federal | ||||
| Auto. Trans. | 600 | 650/600 | .5% | |
| Man. Trans. | 900 | 950/900 | .5% | |
| 350" & 400" 4-Bbl., Calif. | ||||
| Auto. Trans. | 600 | 630/600 | .5% | |
| Man. Trans. | 900 | 950/900 | .5% | |
| 350" 4-Bbl. Z-28, All | ||||
| Auto. Trans. | 700 | 730/700 | .5% | |
| Man. Trans. | 900 | 950/900 | .5% | |
| 454" All | ||||
| Auto. Trans. | 600 | 630/600 | .5% | |
| Man. Trans. | 800 | 850/800 | .5% | |