In message , Stewart
Hargrave writes
From a point at sea, to the circles of your mind, this is hugh:

In message , Stewart
Hargrave writes

Tried both reducing and increasing spark plug gaps.

What gap on your plugs?

I've tried 28 thou (standard for petrol)
25 thou (what I usually set them to for LPG)
22 thou
I think I also tried 20 thou, but this is getting to be a very small
gap.

Currently set at 25 thou

None of the changes made any noticable difference.

I have been thinking that a hotter plug may do something.

It seems to me that the problem is centred around number 4 cylinder,
and that somehow the spark is not igniting the fuel properly. As the
fuel mixture must be the same in all cylinders, and there seems to be
a big voltage across the plug, I guess it has to do with poor spark
formation somehow, but I haven't come up with a plausible reason yet.



25 thou is the norm for gas. Presumably they are standard single point
plugs.
How are you turning off the petrol on your system?
Could it be the distributor itself?
--
hugh
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