Hi guys,
I'm running an 89 Mustang 5.0L HO roller engine in my 68 Mustang, it's supercharged, stroked and boost increased to 9 psi, since increasing to boost it seems to be running rough on 7 cylinders?
The question is I'm running NGK BPR5FS-15 with 1.3mm gap, should it use a different plug and smaller gap.
I've just bougnt but not yet fitted NGK BPR6FS with 0.8mm gap.
Has anyone got any ideas, am I doing the right thing!
Cheers Phil.