CID weight stall gear ratio rpm range Part Number

350-400 3500 2500 3.55-.390 2000-5700 50-3030-6A4 HMT

327-350 3500 3000 4.11-4.56 3000-6200 50-3438-7A5HMT

350-370 3500 3000 4.11-4.56 3000-6500 50-4246-8A6HMT

383-400 3500 3500 4.11-4.56 3000-6500 50-5256-8A4 XTL

Mechanical flat tappet

327-350 3500 3500 4.11-4.56 3000-6200 50-4046-8A4 XTL

350-370 3500 3500 4.11-4.56 3000-6500 50-4854-6A4 XTL

383-400 3500 3500 4.11-4.56 3000-6500 50-5256-8A4 XTL

350-370 3000 4000 4.88-5.13 3500-6700 50-5662-8A4 XTL

383-400 2800 4500 4.88-5.13 3700-7000 50-6270-8A4 XTL

350-400 2400 5000 4.56-4.88 4400-7600 50-6674-8A4 XTL

Mechanical roller tappet

327-350 3500 3500 4.11-4.56 3000-6200 TMR50-4450-7A4

350-370 3500 3500 4.11-4.56 3000-6500 TMR50-4856-6A4

383-400 3500 3500 4.11-4.56 3000-6500 TMR50-5260-8A4

350-370 3000 4000 4.88-5.13 3500-6700 TMR50-5662-8A4

383-400 2800 4500 4.88-5.13 3700-7000 TMR50-6066-8A4

350-370 2400 5000 4.88-5.13 4000-7500 TMR50-6472-8A4

383-400 2400 5500 4.88-5.13 4400-7800 TMR50-6872-8A4

370-400 1800 5500 4.56-5.13 4600-8000 TMR50-6876-9A5

Big Block Chevy

Hydraulic lifter

396-427 3500 3000 3.73-4.11 2800-6000 51-3842-8A5 HMT

427-454 3500 3500 4.11-4.56 3000-6400 51-4246-8A4 HMT

427-454 3000 4000 4.56-4.88 3600-6800 51-4452-8A4 HMT

Mechanical Lifter

396-427 3500 3500 4.11-4.56 3000-6600 51-5056-8A4

454 + 3500 3500 4.11-4.56 3000-6400 51-5258-9A5

454 3500+ 3500 4.11-4.56 3000-6500 51-5666-8A4

396-427 2800 4000 4.56-4.88 3500-7200 51-6270-8A4

Mechanical Roller

396-427 3500 3500 4.11-4.56 3000-6600 TMR51-4854-8A4

454 + 3500 3500 4.11-4.56 3000-6400 TMR51-5258-9A5

454 3500+ 3500 4.11-4.56 3000-6500 TMR51-5666-8A4

396-427 2800 4000 4.56-4.88 3500-7200 TMR51-6270-8A4

454 2500 4500 4.56-4.88 4000-7600 TMR51-6470-9A5

488-520 2000 4500+ 4.11-4.88 4000-7800 TMR51-7478-12A4