Suzuki: Vitara engine problem, spark plug gap, head gasket failure

Question
QUESTION: I have just brought a 1600 soft top vitara, it's been fine until yesterday.It's missing very badly. I changed all plugs.(two outside plugs were slightly sooty, the two inner plugs were wet). I also changed all ht leads and cleaned the dissy cap.

ANSWER: While I have never as much as ridden in a vitara, I can authoritatively state from experience that cleaning a distributor cap and rotor never is a good idea, and has in many circumstances exacerbated ignition problems.  Just replace them, and that will eliminate everything but the coil as an ignition issue.   Make very certain that the spark plug gap is AT LEAST as wide as the vehicle manufacturer specification.  (a narrow gap will create missing on light or slightly trailing throttle)

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QUESTION: I am now being told that the head gasket may have gone.
Also there is a lot of fumes around the car whilst engine is running very strong smelling fumes. Could it be to much fuel getting in engine.

Answer
Excess fuel won't cause head gasket failure, but a leaking head gasket can cause combustion to be upset, possibly from coolant leaking in and not being combustible, and thus getting unburnt fuel coming out the tailpipe. (not uncommon in this sort of case)