Canton, Ohio · Est. 1978
The full Thorley catalog — 1,860+ mandrel-bent header SKUs in stock for every major American V8 from 1964 through 2024, hand-ported and built in Canton by 47 craftsmen.
Engine Family Catalog
Every tile below opens the full fitment grid for that platform: chassis years, tube diameter, collector style, material, and CARB status. The largest header library in North America, sorted the way real engine builders sort it.
Small Block Chevy
Big Block Chevy
Small Block Ford
BBF · Mopar · More
*Torque gains from independent dyno testing by Engine Builder Magazine, March 2019, on a 350ci SBC with stock compression and a tuned Holley 750. Gains vary by engine combo, tune, and altitude — see each SKU page for its own dyno sheet.
“Picked up in two rings. The tech asked about my combo, my bellhousing clearance, and whether I was running a factory clutch linkage — then handed me the exact SKU, the torque-gain range, and the collector size I needed. No upsell, no transfer to sales. Saved me a return and a weekend in the garage.”
Four core tube geometries cover every American V8 build we ship — from a bolt-on street restoration to a 9-second race combo. Torque-gain ranges below come from our own dyno pulls and the Engine Builder Magazine Tri-Y test (March 2019). Your combo, tune, and altitude will move the needle inside those bands.
Our patented 2016 SEMA-winning design. The tuned merge in the secondary pair widens the torque curve without giving up top-end — the choice for most street-driven muscle cars.
Equal-length primaries scavenge hardest at the top of the rev range. Requires dropped oil pan fitment, hood clearance mods, and an open exhaust — not a daily-driver swap.
The bolt-on answer when a long-tube won't clear the steering, the frame rail, or the A/C box. Smaller gains, but the install is a Saturday, not a season.
Drops onto the factory engine stands with zero fabrication. The right pick for a numbers-matching restoration or a daily driver that just needs a leak-free replacement.
Every header above is mandrel-bent in our 38,000 sq-ft Canton, Ohio facility — no crush bends, ever, since 1978 — and ships with a lifetime no-rust-through warranty.
Shop All 1,860+ Header SKUs →Six ASE-certified technicians staff the line. They answer in under 38 seconds on average, walk you through fitment, torque-gain ranges, and collector sizing — and they don't transfer you to sales. Free, in-house, and based in Canton, Ohio since 1978.
No bots. No scripted transfers. No sales-floor triage. Just the same Canton, Ohio shop floor that has shipped 412,000+ header sets since 1978.
