@rene4406 posted:Almost Eureca, almost Victory
With the old ignition system, the engine runs well on all 8 cylinders! There are still some backfires at startup and if I want to reduce the idle too much, below 1100 rpm, it messes up, then a big backfire and it stalls but with a cam that has 60° crossover and vacuum advance which no longer works (the old membrane of the old igniter is pierced), this is perhaps normal. The spark plugs, even the new ones, worked with poor ignition and some may already be more or less out of service, I will order a new set.
So either the Pertronix box is malfunctioning, or the spark plug wires are not suitable for too powerful ignition and create crossfires. I'm going to start with a new spark plug wire harness, I'm thinking of buying these:
https://www.summitracing.com/parts/pnx-808280
because I can buy them from a seller in France.And if it still malfunctions I will just have to change the box wich is brand new but as I bought it almost 5 years ago, there is no point in hoping to have it changed under warranty.
Fords have always had a susceptibility to cross firing through the spark plug wires. It isn't normally this radical though.
For instance, the Ford shop manual on the '68 302s shows that you must keep spark plug wire #7 and #8 at opposite ends of the loom on the valve cover.
That is with the '60s versions of the spark plug wire materials though. The current thick 7, 8 and 9mm silicone covered wires should not have those issues.