About this product
The S&S T124 High Compression long block is a 124 cubic inch Twin Cam crate motor built for aggressive street performance in '99-'17 Big Twins.
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Where a big bore kit rebuilds what you already own, a long block replaces it outright. The T124 High Compression arrives assembled around S&S Super Stock heads and crankcases, so the guesswork of matching a dozen brands of internals never enters the picture. A 10.8:1 compression ratio puts this motor at the sharp end of the T series, aimed at riders who want the throttle to answer immediately.
What Sets the T124 High Compression Engine Apart
The 10.8:1 ratio is the headline, but the supporting parts are what make it live. Easy start 640 gear drive cams work with 1.725:1 rocker arms for .674" of total lift, and a TC3 oil pump and cam plate keep oil pressure steady under load. Special head machining lets the motor accept stock length intake manifolds using S&S manifold size 410, and the breather vent bolt sits in the stock location so stock style air cleaner backplates bolt straight up. The Black Edition swaps the standard chrome covers for gloss black. Designed and manufactured in the USA.
T124 High Compression Specifications
- 124 cubic inch displacement
- Bore x stroke: 4.425" x 4 5/8"
- Compression ratio 10.8:1
- S&S Super Stock cylinder heads and crankcases
- S&S TC3 oil pump and cam support plate
- Easy start 640 gear drive cams
- 1.725:1 rocker arms, .674" total lift
- Machined for stock length intake manifolds, S&S manifold size 410
- Fitments: '07-'16 Touring except Twin Cooled, '06-'17 FXD and FXDWG, '99-'06 Touring and '99-'05 Dyna
What Else You Need With the T124
This motor does not include a carburetor, intake or ignition system. Those are purchased separately from the Tuners and Fuel Systems section. An oil line installation kit is required for '07-'16 Twin Cam engines and for '06-'17 Dyna models: oil line kit and long block installation kit.
Cylinder heads on T series long blocks are '99-'05 style, so owners of 2006 models need a set of '99-'05 style offset intake flanges. The '07-'16 engines are not recommended for Trike models. Professional installation and tuning are strongly advised, and whoever installs the motor should confirm that suspension travel does not create clearance problems between the swingarm or axle and the exhaust, chain and belt guard, or tire.
What Else a T124 Swap Needs
A long block drops in as a complete assembly, but the bike still needs fueling sorted and the driveline checked. Comparing a long block against building your own cases? Our big bore kit guide covers both paths.
- Tuners & Fuel Systems — required for a 124" motor
- Transmission & Clutch — clutch and compensator upgrades for the added torque
- Exhaust Systems
- Gaskets & Seals
- Engine Tools
- Shop all S&S Cycle
Description supplied by MetalCore Harley Supply through its current Shopify listing. Product, performance, and health claims are the seller’s and have not been independently verified by StorkScout.
