How to Identify Vortec Heads in 5 Key Steps
Vortec heads are high-performance cylinder heads from GM, recognizable by their unique casting numbers, combustion chamber shape, and intake bolt patterns. Check for casting codes (e.g., 12558062, 10239906), 8-bolt intake manifold patterns, and heart-shaped combustion chambers to confirm authenticity. Visual and physical traits distinguish them from older small-block Chevy heads.
Key Visual Features of Vortec Heads
- Combustion Chamber Shape: Heart-shaped (unlike oval or "peanut" chambers in older heads).
- Intake Manifold Bolts: 8 bolts (vs. 12 on traditional SBC heads).
- Exhaust Ports: Raised and rectangular (improves flow).
- Rocker Arm Style: Self-aligning, non-adjustable (requires specific rocker arms).
- Valves: 1.94" intake / 1.50" exhaust (larger than pre-1987 heads).
Step-by-Step Identification Guide
- Locate the Casting Number:
- Found on the end of the head (near the exhaust manifold).
- Common Vortec codes:
12558062(1996-2002),10239906(1999-2007),889586(early truck heads).
- Inspect the Intake Bolt Pattern:
- Vortec heads use 8 bolts (4 vertical, 4 angled). Older SBC heads have 12.
- Check the Combustion Chamber:
- Remove a spark plug to view the heart-shaped chamber (use a flashlight).
- Measure the Valve Sizes:
- Intake: 1.94" | Exhaust: 1.50" (standard for most Vortec heads).
- Verify the Rocker Arm System:
- Non-adjustable, self-aligning rockers with press-in studs (no guideplates).
Vortec Heads vs. Traditional SBC Heads: Comparison
| Feature | Vortec Heads | Pre-1987 SBC Heads | 1987-1995 "Fast Burn" Heads |
|---|---|---|---|
| Casting Numbers | 12558062, 10239906, 889586 | 333882, 462624, 14014416 | 14014416, 14093618 |
| Intake Bolt Pattern | 8 bolts (4 vertical) | 12 bolts | 12 bolts |
| Combustion Chamber | Heart-shaped (~64cc) | Oval/peanut (~76cc) | Semi-heart (~62cc) |
| Valve Sizes | 1.94" / 1.50" | 1.94" / 1.50" (some 1.84") | 1.94" / 1.50" |
| Rocker Arms | Self-aligning, non-adjustable | Adjustable, guideplates | Adjustable, guideplates |
| Flow Rate (Intake @ 0.500") | ~220-240 CFM | ~180-200 CFM | ~200-210 CFM |
Common Vortec Head Casting Numbers by Year
- 1996-2002 (L31 Truck Heads):
12558062,10239906 - 1999-2007 (LS-Based Vortecs):
10239906,706(last 3 digits) - Early 1990s (TBI Vortecs):
889586,14093618 - Marine/Performance Variants:
12562365(higher flow, thicker decks).
Tools Needed for Verification
- Flashlight (to inspect chambers).
- Caliper or ruler (measure valve diameters).
- Socket set (remove spark plugs/rocker arms if needed).
- Casting number reference chart (see above).
Warning Signs of Fake or Modified Vortec Heads
- Mismatched Casting Numbers: Re-stamped or ground-off codes.
- Aftermarket Porting: Over-enlarged ports (check for rough edges).
- Non-OEM Rocker Arms: Adjustable rockers may indicate modifications.
- Inconsistent Chamber Volumes: Use a cc'ing kit to verify (~64cc for stock).