All cylinders that have 96mm or larger spigot holes, require that the case seating area be surfaced about 0.060" to provide a full seating area for the cylinder to set on, the same thickness all the way around the cylinder base. Subject to this is thick wall 90.5, 92, and 94 cylinders. This must be done in a milling machine, jig bore, Rotler case center, etc. It cannot be done with our GB 700 tool. If not done, it is possible to start having leaks at the base, especially later in the life of the case. Note: Please be clear that the wording `thick wall' is an expression of the industry and is not reflective of actual cylinder thickness, ONLY the size it is machined on the head and case ends. GB 010 90.5mm Cima/Mahle forged aluminium, 69mm stroke, (standard 39.6mm pin height). These are thick wall with cylinder sizes the same as standard 92mm, case 96mm, head 98mm, 6mm thick crown. Approximately 8.4:1 CR. (POTL) RW: 1.5/2/4. See Notes C, D, E, G. SW 30# GB 012 ** 90.5mm Berg/Cima forged aluminium, specials 82/84mm stroke (33.93mm pin height) case 94.4mm, head 97mm, 8mm thick crown. 132mm long cylinder and 66mm long piston skirt for proper alignment with up to 86mm stroke travel. RW: 1.5/2/4. See Notes B, D, E, F, H. SW 30# GB 012D ** 90.5mm Berg/Cima/Mahle forged aluminium, specials 82/84mm stroke (33.93mm pin height) case 94.4mm, head 97mm, 8mm thick crown. Special Dykes top ring configuration for race applications only. 132mm long cylinder and 66mm long piston skirt for proper alignment with up to 86mm stroke travel. RW: 1.0x1.5/2/4. See Notes B, D, E, F, H. SW 30# GB 014 90.5mm Berg/Cima/Mahle forged aluminium, 82mm stroke (34 mm pin height). These are thick wall with cylinder sizes the same as standard 92mm, case 96mm, head 98mm, 6mm thick crown. (POTL) RW: 1.5/2/4. See Notes C, D, E, G.
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