Th350 & Th400 Holeshot

The B and M AUTOMOTIVE TH350 & TH400 Holeshot torque converter is a high-stall performance transmission component engineered for vehicles running these classic Turbo Hydra-Matic automatic transmissions. With a 2300–2500 RPM stall speed and 10.750-inch bolt circle, this converter is built to multiply engine torque at launch, delivering aggressive acceleration off the line. It's the core component for builders and enthusiasts who demand maximum power transfer during hard acceleration or competition driving.

The 2300–2500 RPM stall specification means the converter holds the transmission in a tighter torque multiplication window before fluid coupling occurs, allowing the engine to build boost or reach higher RPM before the load transfers to the drivetrain. This characteristic is critical for drag racing, off-road recovery, and street performance applications where immediate throttle response matters. The 10.750-inch bolt circle ensures compatibility across TH350, TH400, TH425, TH375, and TH375B applications, making it a versatile option for classic muscle, hot rods, and light-duty truck platforms. Weighing 33.45 lbs, the converter integrates into the transmission bellhousing as a direct bolt-on unit.

This converter targets builders, restoration shops, and performance enthusiasts working with second- and third-generation Turbo Hydra-Matic transmissions. It's suited for vehicles that see regular acceleration events, whether street use, weekend events, or dedicated racing. The higher stall speed reduces slippage under load, improving efficiency and heat management compared to factory converters, which typically stall at lower RPMs. For anyone upgrading TH350 or TH400 transmission performance, proper converter selection is as critical as transmission tuning itself—this unit bridges factory transmissions to modern power levels.