MGB 18G/18GA Engine General Data Specs - Bore, Stroke, Crankshaft, Bearings

This is page 47 of the MGB workshop manual (marked "MGB. Issue 7. 80619", "General Data 1"), presenting the General Data specifications for the 18G/18GA engine. It lists core engine specifications: 4 cylinders, 3.16 in. (80.26 mm) bore, 3.5 in. (89 mm) stroke, 1798 c.c. capacity, firing order 1-3-4-2, pushrod overhead valve operation, compression ratios of 8.8:1 (H.C.) and 8.0:1 (L.C.), compression pressures, torque figures (110/105 lb. ft. at 3,000 rpm), 500 rpm idle speed, and oversize bore limits (.010 in. first, .040 in. max). Detailed dimensional data follows for the crankshaft (main journal 2.1262–2.127 in., crankpin 1.8759–1.8764 in., end-float .004–.005 in.), the three thinwall steel-backed copper-lead main bearings with clearances and undersizes, connecting rods (angular-split big-end, 6.5 in. between centres), shell-type big-end bearings with lengths, clearances, undersizes and crankpin end-float, and aluminium solid-skirt pistons including cylinder clearances, ring count (3 compression, 1 oil control), ring groove widths, and gudgeon pin bore dimensions. A reader can use this page as the factory reference for machining tolerances, bearing selection, and engine rebuilding specifications for the three-main-bearing 18G/18GA MGB engine.