tech question on Leading spark plug hole location

[Rotary Evolution]

Originally Posted by 730RWHP12A

i measured one at sevenstock a few years back, same as leading spark location as the old motors..

the two bottom plugs go straight in, the very top plug is at a 45 degree angle

even so, the third plug would widen the firing range. the better question is if the leading plug is in the same location as in the early engines. they did have to squeeze 3 plugs in there somehow so it may have just been a compromise they had to make. looking at a rotor housing it looks to me as if they had to move both the bottom and middle plug downward to even fit the top plug casting otherwise it would be humping the 13B trailing plug location.

i highly doubt the coolant passages were cast in the same location in order to fit everything. the housings weren't based off of any previous design specs.