243 vs 799 vs 706 vs 317 heads
All four are cathedral-port LS heads:
Last updated
| Casting | Chamber | Found on | Notes |
|---|---|---|---|
| 243 | 64 cc | LS6, LS2 | Best-flowing common cathedral head |
| 799 | 65 cc | Aluminum 5.3 trucks (e.g., L33) | "Truck 243": nearly identical ports; lacks LS6 valve springs/lightweight valves |
| 706 | 61 cc | 4.8/5.3 trucks | Small chambers, 1.89/1.55 in valves; good for raising compression |
| 317 | 71 cc | Iron 6.0 trucks (LQ4) | Large chambers, lower compression (boost-friendly) |
A 5.3 project with lightly shaved 706 heads and a BTR Truck Norris cam made about 430 hp. For a 5.3 upgrade, 243/799 heads are the classic budget swap. Rectangle-port heads (823 etc.) need a rectangle-port intake.