Ok.

Not used to High compression heads.

Running a willie Bosch clone dizzy and champion plugs what is recommended for plug and spark gaps?

Cap and rotor do look a bit dirty. Leads are not that old.

I had feeble spark on saturday with a flat battery. But after a night charge I currently have no spark despite swapping the condensor. Gave up when the rain came. Will set too with a multimeter next time Ive got a minuite.

Im certain the coil is wired up **** about face.

This was dads car, I dont know how old bits are like I do with mine.

To the best of my knowledge AMC never varied from their recommendation for plug points to be set at 18 to 20 thou (though I tend to set mine a little wider at 22 to 25 thou without a problem - so far!).
Bosch recommend ( I believe ) that points on their 009 distributor be gapped at 18 thou. (see page 13 of PWA7C mag. for MAY 2016)

Ian Mc.

Location: Shropshire

When this topic first appeared, the comment about auto transformer effect set me a pondering. When the points break a high voltage appears across the pri; if + earth this is – at the points end, if –ve earth, + at the points end. The secondary if connected in the same direction experiences an induced voltage of the same polarity. I have drawn every conceivable combination of direction of connection of secondary and leads etc but I can only get a –ve spark in series additive with the pri and battery (and hence earth) with + earth battery. (Points in effect tapped off part way up the coil)
Maybe I have got it wrong somewhere (again, according several) but perhaps this was the reason for adoption of + earth, not reduced corrosion, the usual somewhat curious “explanation”. It is a few hundred volts cf several thousand, so not vital. I did not consider the lesser earth path thru the condenser.

Anyone who enjoys puzzles can try diagrams for themselves.

It is all related to Lenzs law which, as Tony notes above, the internet seems to have made incredibly complex since it was taught to my father on a trades course in the 3rd form, somewhat before. You would think someone could provide Wikipedia with understandable examples?

In my Seven when in everyday use I could detect reduced harshness with smaller plug gaps. I reckon a smaller spark effectively retards the ignition process slightly.

Location: Auckland, NZ