hi guys,

currently im trying to license a v8 xf however emmission test has to be done and im having trouble with misfire in 8 th cylinder..

i know its the 8th cylinder because if i take off spark plug lead from each cylinder, the motor sounds different when at idle. if i take 8th cylinder lead off, engine sounds exactly the same......

this is what i have

351 cleveland d block, mild cam ( nothing toooo fancy)
brand new holley 600
egr plate from thermaquad and adapter plate to suit holley
new leads, plugs, dizzycap and rotor
electronic dizzy and crane fireball amplifier thingy (old one) however it sparks great
standard intake cast manifold and standard cast exhaust manifolds
original factory xd xe air cleaner


TESTS I HAVE DONE

timing is at 10 degrees
compression test all cylinders 148- 150
cylinder leakage test all in the green (perfect)
blocked off the egr valve
tested pcv valve on rocker cover all is fine
sprayed carby cleaner around for vacume leaks

dizzy has not been replaced so im thinking it could be that.........

but then again carby could be very lean as the plugs are very white at the ends

when the car is driven at 60 - 70 km , it is stuttering and not smooth but is drivable, when you floor it, its got power and goes good

what can it be ... hope i have explained enough

Is there still spark coming out of that lead?
switch that spark plug to another cylinder.

agreed, either change out that spark plug for a new one or swap it with another cylinder and see if it still misses on N.O 8.

The dizzy might need to be regraphed.....?????

That would affect all cylinders.