When two lines are perpendicular to each other the product of their slopes is equal to -1.m1*m2 = -1
The firing order for the 4.9 is as follows 1 8 4 3 6 5 7 2Looking at the engine and starting from left to right (front) .... Cyclinder 1 3 5 7Looking at the engine and starting from Leftto right (back) .... Cyclinder 2 4 6 8The Distributor is set up so that # 1 spark plug is to the right of the power supply and goes counter clockwise thus , using the mark in the engine block to align to distributor, the power supply should be point direct at the mark, making #1 and # 6 perpidicular to the engine.EDIT: This is a brilliant answer ! I wanted to award a trust-point - but, since it cam from a network rather than a registered individual, I couldn't. WELL DONE anyway - Snakester1962 (Supervisor)