Mast Motorsports Ls7 Crate Motor Block
MAST 427 SPECS
ENGINE TYPE GM LS7
DISPLACEMENT 427 ci
BORE X STROKE 4.125 x 4.000
COMPRESSION RATIO 11.7:1
DECK HEIGHT (ACTUAL) 9.230
ROD LENGTH 6.125
MAIN BEARING CLEARANCE 0.0023-0.0026
ROD BEARING CLEARANCE 0.0024-0.0028
ROD SIDE-CLEARANCE 0.018
CRANKSHAFT ENDPLAY 0.007
CAMSHAFT ENDPLAY 0.006
PISTON-TO-WALL CLEARANCE 0.0040
PISTON TOP RING END-GAP 0.023
PISTON SECOND RING END-GAP 0.020
PISTON COMPRESSION HEIGHT 1.105
PISTON DOME VOLUME -3cc
PISTON-DECK CLEARANCE 0
HEAD GASKET COMPRESSED THICKNESS 0.040
COMBUSTION CHAMBER VOLUME 70 cc
VALVE DIAMETER (INTAKE/EXHAUST) 2.200/1.625
VALVESPRING DIAMETER 1.280
VALVESPRING SEAT PRESSURE 145 lbs
VALVESPRING OPEN PRESSURE 410 lbs
CAM SPECS 246/260-at-0.050; 0.659/0.666; 114
FUEL INJECTOR SIZE 39 lb/hr
FUEL TYPE 93 octane
MAIN CAP BOLT 60 lb-ft (20 lb-ft side bolts)
ROD BOLT 75 lb-ft
HEAD BOLT 70 lb-ft (23 lb-ft top bolts)